core/num/uint_macros.rs
1macro_rules! uint_impl {
2 (
3 Self = $SelfT:ty,
4 ActualT = $ActualT:ident,
5 SignedT = $SignedT:ident,
6
7 // These are all for use *only* in doc comments.
8 // As such, they're all passed as literals -- passing them as a string
9 // literal is fine if they need to be multiple code tokens.
10 // In non-comments, use the associated constants rather than these.
11 BITS = $BITS:literal,
12 BITS_MINUS_ONE = $BITS_MINUS_ONE:literal,
13 MAX = $MaxV:literal,
14 rot = $rot:literal,
15 rot_op = $rot_op:literal,
16 rot_result = $rot_result:literal,
17 fsh_op = $fsh_op:literal,
18 fshl_result = $fshl_result:literal,
19 fshr_result = $fshr_result:literal,
20 clmul_lhs = $clmul_lhs:literal,
21 clmul_rhs = $clmul_rhs:literal,
22 clmul_result = $clmul_result:literal,
23 swap_op = $swap_op:literal,
24 swapped = $swapped:literal,
25 reversed = $reversed:literal,
26 le_bytes = $le_bytes:literal,
27 be_bytes = $be_bytes:literal,
28 to_xe_bytes_doc = $to_xe_bytes_doc:expr,
29 from_xe_bytes_doc = $from_xe_bytes_doc:expr,
30 bound_condition = $bound_condition:literal,
31 ) => {
32 /// The smallest value that can be represented by this integer type.
33 ///
34 /// # Examples
35 ///
36 /// ```
37 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN, 0);")]
38 /// ```
39 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
40 pub const MIN: Self = 0;
41
42 /// The largest value that can be represented by this integer type
43 #[doc = concat!("(2<sup>", $BITS, "</sup> − 1", $bound_condition, ").")]
44 ///
45 /// # Examples
46 ///
47 /// ```
48 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX, ", stringify!($MaxV), ");")]
49 /// ```
50 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
51 pub const MAX: Self = !0;
52
53 /// The size of this integer type in bits.
54 ///
55 /// # Examples
56 ///
57 /// ```
58 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
59 /// ```
60 #[stable(feature = "int_bits_const", since = "1.53.0")]
61 pub const BITS: u32 = Self::MAX.count_ones();
62
63 /// Returns the number of ones in the binary representation of `self`.
64 ///
65 /// # Examples
66 ///
67 /// ```
68 #[doc = concat!("let n = 0b01001100", stringify!($SelfT), ";")]
69 /// assert_eq!(n.count_ones(), 3);
70 ///
71 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
72 #[doc = concat!("assert_eq!(max.count_ones(), ", stringify!($BITS), ");")]
73 ///
74 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
75 /// assert_eq!(zero.count_ones(), 0);
76 /// ```
77 #[stable(feature = "rust1", since = "1.0.0")]
78 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
79 #[doc(alias = "popcount")]
80 #[doc(alias = "popcnt")]
81 #[must_use = "this returns the result of the operation, \
82 without modifying the original"]
83 #[inline(always)]
84 pub const fn count_ones(self) -> u32 {
85 return intrinsics::ctpop(self);
86 }
87
88 /// Returns the number of zeros in the binary representation of `self`.
89 ///
90 /// # Examples
91 ///
92 /// ```
93 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
94 #[doc = concat!("assert_eq!(zero.count_zeros(), ", stringify!($BITS), ");")]
95 ///
96 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
97 /// assert_eq!(max.count_zeros(), 0);
98 /// ```
99 ///
100 /// This is heavily dependent on the width of the type, and thus
101 /// might give surprising results depending on type inference:
102 /// ```
103 /// # fn foo(_: u8) {}
104 /// # fn bar(_: u16) {}
105 /// let lucky = 7;
106 /// foo(lucky);
107 /// assert_eq!(lucky.count_zeros(), 5);
108 /// assert_eq!(lucky.count_ones(), 3);
109 ///
110 /// let lucky = 7;
111 /// bar(lucky);
112 /// assert_eq!(lucky.count_zeros(), 13);
113 /// assert_eq!(lucky.count_ones(), 3);
114 /// ```
115 /// You might want to use [`Self::count_ones`] instead, or emphasize
116 /// the type you're using in the call rather than method syntax:
117 /// ```
118 /// let small = 1;
119 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::count_zeros(small), ", stringify!($BITS_MINUS_ONE) ,");")]
120 /// ```
121 #[stable(feature = "rust1", since = "1.0.0")]
122 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
123 #[must_use = "this returns the result of the operation, \
124 without modifying the original"]
125 #[inline(always)]
126 pub const fn count_zeros(self) -> u32 {
127 (!self).count_ones()
128 }
129
130 /// Returns the number of leading zeros in the binary representation of `self`.
131 ///
132 /// Depending on what you're doing with the value, you might also be interested in the
133 /// [`ilog2`] function which returns a consistent number, even if the type widens.
134 ///
135 /// # Examples
136 ///
137 /// ```
138 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX >> 2;")]
139 /// assert_eq!(n.leading_zeros(), 2);
140 ///
141 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
142 #[doc = concat!("assert_eq!(zero.leading_zeros(), ", stringify!($BITS), ");")]
143 ///
144 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
145 /// assert_eq!(max.leading_zeros(), 0);
146 /// ```
147 #[doc = concat!("[`ilog2`]: ", stringify!($SelfT), "::ilog2")]
148 #[stable(feature = "rust1", since = "1.0.0")]
149 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
150 #[must_use = "this returns the result of the operation, \
151 without modifying the original"]
152 #[inline(always)]
153 pub const fn leading_zeros(self) -> u32 {
154 return intrinsics::ctlz(self as $ActualT);
155 }
156
157 /// Returns the number of trailing zeros in the binary representation
158 /// of `self`.
159 ///
160 /// # Examples
161 ///
162 /// ```
163 #[doc = concat!("let n = 0b0101000", stringify!($SelfT), ";")]
164 /// assert_eq!(n.trailing_zeros(), 3);
165 ///
166 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
167 #[doc = concat!("assert_eq!(zero.trailing_zeros(), ", stringify!($BITS), ");")]
168 ///
169 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
170 #[doc = concat!("assert_eq!(max.trailing_zeros(), 0);")]
171 /// ```
172 #[stable(feature = "rust1", since = "1.0.0")]
173 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
174 #[must_use = "this returns the result of the operation, \
175 without modifying the original"]
176 #[inline(always)]
177 pub const fn trailing_zeros(self) -> u32 {
178 return intrinsics::cttz(self);
179 }
180
181 /// Returns the number of leading ones in the binary representation of `self`.
182 ///
183 /// # Examples
184 ///
185 /// ```
186 #[doc = concat!("let n = !(", stringify!($SelfT), "::MAX >> 2);")]
187 /// assert_eq!(n.leading_ones(), 2);
188 ///
189 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
190 /// assert_eq!(zero.leading_ones(), 0);
191 ///
192 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
193 #[doc = concat!("assert_eq!(max.leading_ones(), ", stringify!($BITS), ");")]
194 /// ```
195 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
196 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
197 #[must_use = "this returns the result of the operation, \
198 without modifying the original"]
199 #[inline(always)]
200 pub const fn leading_ones(self) -> u32 {
201 (!self).leading_zeros()
202 }
203
204 /// Returns the number of trailing ones in the binary representation
205 /// of `self`.
206 ///
207 /// # Examples
208 ///
209 /// ```
210 #[doc = concat!("let n = 0b1010111", stringify!($SelfT), ";")]
211 /// assert_eq!(n.trailing_ones(), 3);
212 ///
213 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
214 /// assert_eq!(zero.trailing_ones(), 0);
215 ///
216 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
217 #[doc = concat!("assert_eq!(max.trailing_ones(), ", stringify!($BITS), ");")]
218 /// ```
219 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
220 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
221 #[must_use = "this returns the result of the operation, \
222 without modifying the original"]
223 #[inline(always)]
224 pub const fn trailing_ones(self) -> u32 {
225 (!self).trailing_zeros()
226 }
227
228 /// Returns the minimum number of bits required to represent `self`.
229 ///
230 /// This method returns zero if `self` is zero.
231 ///
232 /// # Examples
233 ///
234 /// ```
235 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".bit_width(), 0);")]
236 #[doc = concat!("assert_eq!(0b111_", stringify!($SelfT), ".bit_width(), 3);")]
237 #[doc = concat!("assert_eq!(0b1110_", stringify!($SelfT), ".bit_width(), 4);")]
238 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.bit_width(), ", stringify!($BITS), ");")]
239 /// ```
240 #[stable(feature = "uint_bit_width", since = "1.97.0")]
241 #[rustc_const_stable(feature = "uint_bit_width", since = "1.97.0")]
242 #[must_use = "this returns the result of the operation, \
243 without modifying the original"]
244 #[inline(always)]
245 pub const fn bit_width(self) -> u32 {
246 Self::BITS - self.leading_zeros()
247 }
248
249 /// Returns `self` with only the most significant bit set, or `0` if
250 /// the input is `0`.
251 ///
252 /// # Examples
253 ///
254 /// ```
255 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
256 ///
257 /// assert_eq!(n.isolate_highest_one(), 0b_01000000);
258 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_highest_one(), 0);")]
259 /// ```
260 #[stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
261 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
262 #[must_use = "this returns the result of the operation, \
263 without modifying the original"]
264 #[inline(always)]
265 pub const fn isolate_highest_one(self) -> Self {
266 self & (((1 as $SelfT) << (<$SelfT>::BITS - 1)).wrapping_shr(self.leading_zeros()))
267 }
268
269 /// Returns `self` with only the least significant bit set, or `0` if
270 /// the input is `0`.
271 ///
272 /// # Examples
273 ///
274 /// ```
275 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
276 ///
277 /// assert_eq!(n.isolate_lowest_one(), 0b_00000100);
278 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_lowest_one(), 0);")]
279 /// ```
280 #[stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
281 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
282 #[must_use = "this returns the result of the operation, \
283 without modifying the original"]
284 #[inline(always)]
285 pub const fn isolate_lowest_one(self) -> Self {
286 self & self.wrapping_neg()
287 }
288
289 /// Returns the index of the highest bit set to one in `self`, or `None`
290 /// if `self` is `0`.
291 ///
292 /// Note that this is equivalent to [`checked_ilog2`](Self::checked_ilog2).
293 ///
294 /// # Examples
295 ///
296 /// ```
297 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".highest_one(), None);")]
298 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".highest_one(), Some(0));")]
299 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".highest_one(), Some(4));")]
300 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".highest_one(), Some(4));")]
301 /// ```
302 #[stable(feature = "int_lowest_highest_one", since = "1.97.0")]
303 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "1.97.0")]
304 #[must_use = "this returns the result of the operation, \
305 without modifying the original"]
306 #[inline(always)]
307 pub const fn highest_one(self) -> Option<u32> {
308 match NonZero::new(self) {
309 Some(v) => Some(v.highest_one()),
310 None => None,
311 }
312 }
313
314 /// Returns the index of the lowest bit set to one in `self`, or `None`
315 /// if `self` is `0`.
316 ///
317 /// # Examples
318 ///
319 /// ```
320 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".lowest_one(), None);")]
321 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".lowest_one(), Some(0));")]
322 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".lowest_one(), Some(4));")]
323 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".lowest_one(), Some(0));")]
324 /// ```
325 #[stable(feature = "int_lowest_highest_one", since = "1.97.0")]
326 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "1.97.0")]
327 #[must_use = "this returns the result of the operation, \
328 without modifying the original"]
329 #[inline(always)]
330 pub const fn lowest_one(self) -> Option<u32> {
331 match NonZero::new(self) {
332 Some(v) => Some(v.lowest_one()),
333 None => None,
334 }
335 }
336
337 /// Returns the bit pattern of `self` reinterpreted as a signed integer of the same size.
338 ///
339 /// This produces the same result as an `as` cast, but ensures that the bit-width remains
340 /// the same.
341 ///
342 /// # Examples
343 ///
344 /// ```
345 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
346 ///
347 #[doc = concat!("assert_eq!(n.cast_signed(), -1", stringify!($SignedT), ");")]
348 /// ```
349 #[stable(feature = "integer_sign_cast", since = "1.87.0")]
350 #[rustc_const_stable(feature = "integer_sign_cast", since = "1.87.0")]
351 #[must_use = "this returns the result of the operation, \
352 without modifying the original"]
353 #[inline(always)]
354 pub const fn cast_signed(self) -> $SignedT {
355 self as $SignedT
356 }
357
358 /// Saturating conversion of `self` to a signed integer of the same size.
359 ///
360 /// The signed integer's maximum value is returned if `self` is larger
361 /// than the maximum positive value representable by the signed integer.
362 ///
363 /// For other kinds of signed integer casts, see
364 /// [`cast_signed`](Self::cast_signed),
365 /// [`checked_cast_signed`](Self::checked_cast_signed),
366 /// or [`strict_cast_signed`](Self::strict_cast_signed).
367 ///
368 /// # Examples
369 ///
370 /// ```
371 /// #![feature(integer_cast_extras)]
372 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
373 ///
374 #[doc = concat!("assert_eq!(n.saturating_cast_signed(), ", stringify!($SignedT), "::MAX);")]
375 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".saturating_cast_signed(), 64", stringify!($SignedT), ");")]
376 /// ```
377 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
378 #[unstable(feature = "integer_cast_extras", issue = "154650")]
379 #[must_use = "this returns the result of the operation, \
380 without modifying the original"]
381 #[inline(always)]
382 pub const fn saturating_cast_signed(self) -> $SignedT {
383 // Clamp to the signed integer max size, which is ActualT::MAX >> 1.
384 if self <= <$SignedT>::MAX.cast_unsigned() {
385 self.cast_signed()
386 } else {
387 <$SignedT>::MAX
388 }
389 }
390
391 /// Checked conversion of `self` to a signed integer of the same size,
392 /// returning `None` if `self` is larger than the signed integer's
393 /// maximum value.
394 ///
395 /// For other kinds of signed integer casts, see
396 /// [`cast_signed`](Self::cast_signed),
397 /// [`saturating_cast_signed`](Self::saturating_cast_signed),
398 /// or [`strict_cast_signed`](Self::strict_cast_signed).
399 ///
400 /// # Examples
401 ///
402 /// ```
403 /// #![feature(integer_cast_extras)]
404 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
405 ///
406 #[doc = concat!("assert_eq!(n.checked_cast_signed(), None);")]
407 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_cast_signed(), Some(64", stringify!($SignedT), "));")]
408 /// ```
409 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
410 #[unstable(feature = "integer_cast_extras", issue = "154650")]
411 #[must_use = "this returns the result of the operation, \
412 without modifying the original"]
413 #[inline(always)]
414 pub const fn checked_cast_signed(self) -> Option<$SignedT> {
415 if self <= <$SignedT>::MAX.cast_unsigned() {
416 Some(self.cast_signed())
417 } else {
418 None
419 }
420 }
421
422 /// Strict conversion of `self` to a signed integer of the same size,
423 /// which panics if `self` is larger than the signed integer's maximum
424 /// value.
425 ///
426 /// For other kinds of signed integer casts, see
427 /// [`cast_signed`](Self::cast_signed),
428 /// [`checked_cast_signed`](Self::checked_cast_signed),
429 /// or [`saturating_cast_signed`](Self::saturating_cast_signed).
430 ///
431 /// # Examples
432 ///
433 /// ```should_panic
434 /// #![feature(integer_cast_extras)]
435 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_cast_signed();")]
436 /// ```
437 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
438 #[unstable(feature = "integer_cast_extras", issue = "154650")]
439 #[must_use = "this returns the result of the operation, \
440 without modifying the original"]
441 #[inline]
442 #[track_caller]
443 pub const fn strict_cast_signed(self) -> $SignedT {
444 match self.checked_cast_signed() {
445 Some(n) => n,
446 None => imp::overflow_panic::cast_integer(),
447 }
448 }
449
450 /// Shifts the bits to the left by a specified amount, `n`,
451 /// wrapping the truncated bits to the end of the resulting integer.
452 ///
453 /// `rotate_left(n)` is equivalent to applying `rotate_left(1)` a total of `n` times. In
454 /// particular, a rotation by the number of bits in `self` returns the input value
455 /// unchanged.
456 ///
457 /// Please note this isn't the same operation as the `<<` shifting operator!
458 ///
459 /// # Examples
460 ///
461 /// ```
462 #[doc = concat!("let n = ", $rot_op, stringify!($SelfT), ";")]
463 #[doc = concat!("let m = ", $rot_result, ";")]
464 ///
465 #[doc = concat!("assert_eq!(n.rotate_left(", $rot, "), m);")]
466 #[doc = concat!("assert_eq!(n.rotate_left(1024), n);")]
467 /// ```
468 #[stable(feature = "rust1", since = "1.0.0")]
469 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
470 #[must_use = "this returns the result of the operation, \
471 without modifying the original"]
472 #[inline(always)]
473 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
474 pub const fn rotate_left(self, n: u32) -> Self {
475 return intrinsics::rotate_left(self, n);
476 }
477
478 /// Shifts the bits to the right by a specified amount, `n`,
479 /// wrapping the truncated bits to the beginning of the resulting
480 /// integer.
481 ///
482 /// `rotate_right(n)` is equivalent to applying `rotate_right(1)` a total of `n` times. In
483 /// particular, a rotation by the number of bits in `self` returns the input value
484 /// unchanged.
485 ///
486 /// Please note this isn't the same operation as the `>>` shifting operator!
487 ///
488 /// # Examples
489 ///
490 /// ```
491 #[doc = concat!("let n = ", $rot_result, stringify!($SelfT), ";")]
492 #[doc = concat!("let m = ", $rot_op, ";")]
493 ///
494 #[doc = concat!("assert_eq!(n.rotate_right(", $rot, "), m);")]
495 #[doc = concat!("assert_eq!(n.rotate_right(1024), n);")]
496 /// ```
497 #[stable(feature = "rust1", since = "1.0.0")]
498 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
499 #[must_use = "this returns the result of the operation, \
500 without modifying the original"]
501 #[inline(always)]
502 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
503 pub const fn rotate_right(self, n: u32) -> Self {
504 return intrinsics::rotate_right(self, n);
505 }
506
507 /// Performs a left funnel shift.
508 ///
509 /// This operation can be thought of as concatenating `self` and `right` into an
510 /// integer twice the size of
511 #[doc = concat!("`", stringify!($SelfT) , "`,")]
512 /// performing a left shift by `n`, and returning the **left half** of the result.
513 ///
514 /// The name comes from "funneling" a wider integer to a narrower integer.
515 ///
516 /// # Panics
517 ///
518 /// This function will panic if `n` is greater than or equal to the number of
519 /// bits in `self`.
520 ///
521 /// # Examples
522 ///
523 /// ```
524 /// #![feature(funnel_shifts)]
525 ///
526 #[doc = concat!("let a = ", $rot_op, "_", stringify!($SelfT), ";")]
527 #[doc = concat!("let b = ", $fsh_op, "_", stringify!($SelfT), ";")]
528 ///
529 #[doc = concat!("assert_eq!(a.funnel_shl(b, ", $rot, "), ", $fshl_result, ");")]
530 ///
531 /// // Using zeros as the right operand acts as a normal shift left
532 #[doc = concat!("assert_eq!(a.funnel_shl(0, ", $rot, "), a << ", $rot, ");")]
533 ///
534 /// // Shifting by 0 returns `self` unchanged
535 #[doc = concat!("assert_eq!(a.funnel_shl(b, 0), a);")]
536 ///
537 /// // Using the same value as the right operand acts as a rotate
538 #[doc = concat!("assert_eq!(a.funnel_shl(a, ", $rot, "), a.rotate_left(", $rot, "));")]
539 /// ```
540 ///
541 /// Note that while `funnel_shl` can act as a rotate, it does not allow for
542 /// rotating by an unbounded amount like [`rotate_left`](Self::rotate_left) does:
543 ///
544 /// ```should_panic
545 /// #![feature(funnel_shifts)]
546 ///
547 #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
548 /// // Okay
549 #[doc = concat!("let _ = a.rotate_left(", stringify!($SelfT), "::BITS);")]
550 /// // Panics
551 #[doc = concat!("let _ = a.funnel_shl(a, ", stringify!($SelfT), "::BITS);")]
552 /// ```
553 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
554 #[unstable(feature = "funnel_shifts", issue = "145686")]
555 #[must_use = "this returns the result of the operation, without modifying the original"]
556 #[inline(always)]
557 pub const fn funnel_shl(self, right: Self, n: u32) -> Self {
558 assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
559 // SAFETY: just checked that `shift` is in-range
560 unsafe { self.unchecked_funnel_shl(right, n) }
561 }
562
563 /// Performs a right funnel shift.
564 ///
565 /// This operation can be thought of as concatenating `self` and `right` into an
566 /// integer twice the size of
567 #[doc = concat!("`", stringify!($SelfT) , "`,")]
568 /// performing a right shift by `n`, and returning the **left half** of the result.
569 ///
570 /// The name comes from "funneling" a wider integer to a narrower integer.
571 ///
572 /// # Panics
573 ///
574 /// This function will panic if `n` is greater than or equal to the number of
575 /// bits in `self`.
576 ///
577 /// # Examples
578 ///
579 /// ```
580 /// #![feature(funnel_shifts)]
581 ///
582 #[doc = concat!("let a = ", $rot_op, "_", stringify!($SelfT), ";")]
583 #[doc = concat!("let b = ", $fsh_op, "_", stringify!($SelfT), ";")]
584 ///
585 #[doc = concat!("assert_eq!(a.funnel_shr(b, ", $rot, "), ", $fshr_result, ");")]
586 ///
587 /// // Using zeros as the left operand acts as a normal shift right
588 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".funnel_shr(a, ", $rot, "), a >> ", $rot, ");")]
589 ///
590 /// // Shifting by 0 returns `right` unchanged
591 #[doc = concat!("assert_eq!(b.funnel_shr(a, 0), a);")]
592 ///
593 /// // Using the same value as the right operand acts as a rotate
594 #[doc = concat!("assert_eq!(a.funnel_shr(a, ", $rot, "), a.rotate_right(", $rot, "));")]
595 /// ```
596 ///
597 /// Note that while `funnel_shr` can act as a rotate, it does not allow for
598 /// rotating by an unbounded amount like [`rotate_right`](Self::rotate_right) does:
599 ///
600 /// ```should_panic
601 /// #![feature(funnel_shifts)]
602 ///
603 #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
604 /// // Okay
605 #[doc = concat!("let _ = a.rotate_right(", stringify!($SelfT), "::BITS);")]
606 /// // Panics
607 #[doc = concat!("let _ = a.funnel_shr(a, ", stringify!($SelfT), "::BITS);")]
608 /// ```
609 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
610 #[unstable(feature = "funnel_shifts", issue = "145686")]
611 #[must_use = "this returns the result of the operation, without modifying the original"]
612 #[inline(always)]
613 pub const fn funnel_shr(self, right: Self, n: u32) -> Self {
614 assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
615 // SAFETY: just checked that `shift` is in-range
616 unsafe { self.unchecked_funnel_shr(right, n) }
617 }
618
619 /// Unchecked funnel shift left.
620 ///
621 /// # Safety
622 ///
623 /// This results in undefined behavior if `n` is greater than or equal to
624 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
625 /// i.e. when [`funnel_shl`](Self::funnel_shl) would panic.
626 ///
627 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
628 #[unstable(feature = "funnel_shifts", issue = "145686")]
629 #[must_use = "this returns the result of the operation, without modifying the original"]
630 #[inline(always)]
631 #[track_caller]
632 pub const unsafe fn unchecked_funnel_shl(self, right: Self, n: u32) -> Self {
633 assert_unsafe_precondition!(
634 check_language_ub,
635 concat!(stringify!($SelfT), "::unchecked_funnel_shl cannot overflow"),
636 (n: u32 = n) => n < <$ActualT>::BITS,
637 );
638
639 // SAFETY: this is guaranteed to be safe by the caller.
640 unsafe {
641 intrinsics::unchecked_funnel_shl(self, right, n)
642 }
643 }
644
645 /// Unchecked funnel shift right.
646 ///
647 /// # Safety
648 ///
649 /// This results in undefined behavior if `n` is greater than or equal to
650 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
651 /// i.e. when [`funnel_shr`](Self::funnel_shr) would panic.
652 ///
653 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
654 #[unstable(feature = "funnel_shifts", issue = "145686")]
655 #[must_use = "this returns the result of the operation, without modifying the original"]
656 #[inline(always)]
657 #[track_caller]
658 pub const unsafe fn unchecked_funnel_shr(self, right: Self, n: u32) -> Self {
659 assert_unsafe_precondition!(
660 check_language_ub,
661 concat!(stringify!($SelfT), "::unchecked_funnel_shr cannot overflow"),
662 (n: u32 = n) => n < <$ActualT>::BITS,
663 );
664
665 // SAFETY: this is guaranteed to be safe by the caller.
666 unsafe {
667 intrinsics::unchecked_funnel_shr(self, right, n)
668 }
669 }
670
671 /// Performs a carry-less multiplication, returning the lower bits.
672 ///
673 /// This operation is similar to long multiplication in base 2, except that exclusive or is
674 /// used instead of addition. The implementation is equivalent to:
675 ///
676 /// ```no_run
677 #[doc = concat!("pub fn carryless_mul(lhs: ", stringify!($SelfT), ", rhs: ", stringify!($SelfT), ") -> ", stringify!($SelfT), "{")]
678 /// let mut retval = 0;
679 #[doc = concat!(" for i in 0..", stringify!($SelfT), "::BITS {")]
680 /// if (rhs >> i) & 1 != 0 {
681 /// // long multiplication would use +=
682 /// retval ^= lhs << i;
683 /// }
684 /// }
685 /// retval
686 /// }
687 /// ```
688 ///
689 /// The actual implementation is more efficient, and on some platforms lowers directly to a
690 /// dedicated instruction.
691 ///
692 /// # Uses
693 ///
694 /// Carryless multiplication can be used to turn a bitmask of quote characters into a
695 /// bit mask of characters surrounded by quotes:
696 ///
697 /// ```no_run
698 /// r#"abc xxx "foobar" zzz "a"!"#; // input string
699 /// 0b0000000010000001000001010; // quote_mask
700 /// 0b0000000001111110000000100; // quote_mask.carryless_mul(!0) & !quote_mask
701 /// ```
702 ///
703 /// Another use is in cryptography, where carryless multiplication allows for efficient
704 /// implementations of polynomial multiplication in `GF(2)[X]`, the polynomial ring
705 /// over `GF(2)`.
706 ///
707 /// # Examples
708 ///
709 /// ```
710 /// #![feature(uint_carryless_mul)]
711 ///
712 #[doc = concat!("let a = ", $clmul_lhs, stringify!($SelfT), ";")]
713 #[doc = concat!("let b = ", $clmul_rhs, stringify!($SelfT), ";")]
714 ///
715 #[doc = concat!("assert_eq!(a.carryless_mul(b), ", $clmul_result, ");")]
716 /// ```
717 #[rustc_const_unstable(feature = "uint_carryless_mul", issue = "152080")]
718 #[doc(alias = "clmul")]
719 #[unstable(feature = "uint_carryless_mul", issue = "152080")]
720 #[must_use = "this returns the result of the operation, \
721 without modifying the original"]
722 #[inline(always)]
723 pub const fn carryless_mul(self, rhs: Self) -> Self {
724 intrinsics::carryless_mul(self, rhs)
725 }
726
727 /// Reverses the byte order of the integer.
728 ///
729 /// # Examples
730 ///
731 /// ```
732 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
733 /// let m = n.swap_bytes();
734 ///
735 #[doc = concat!("assert_eq!(m, ", $swapped, ");")]
736 /// ```
737 #[stable(feature = "rust1", since = "1.0.0")]
738 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
739 #[must_use = "this returns the result of the operation, \
740 without modifying the original"]
741 #[inline(always)]
742 pub const fn swap_bytes(self) -> Self {
743 intrinsics::bswap(self as $ActualT) as Self
744 }
745
746 /// Returns an integer with the bit locations specified by `mask` packed
747 /// contiguously into the least significant bits of the result.
748 /// ```
749 /// #![feature(uint_gather_scatter_bits)]
750 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1011_1100;")]
751 ///
752 /// assert_eq!(n.extract_bits(0b0010_0100), 0b0000_0011);
753 /// assert_eq!(n.extract_bits(0xF0), 0b0000_1011);
754 /// ```
755 #[doc(alias = "pext")]
756 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
757 #[must_use = "this returns the result of the operation, \
758 without modifying the original"]
759 #[inline]
760 pub const fn extract_bits(self, mask: Self) -> Self {
761 imp::int_bits::$ActualT::extract_impl(self as $ActualT, mask as $ActualT) as $SelfT
762 }
763
764 /// Returns an integer with the least significant bits of `self`
765 /// distributed to the bit locations specified by `mask`.
766 /// ```
767 /// #![feature(uint_gather_scatter_bits)]
768 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1010_1101;")]
769 ///
770 /// assert_eq!(n.deposit_bits(0b0101_0101), 0b0101_0001);
771 /// assert_eq!(n.deposit_bits(0xF0), 0b1101_0000);
772 /// ```
773 #[doc(alias = "pdep")]
774 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
775 #[must_use = "this returns the result of the operation, \
776 without modifying the original"]
777 #[inline]
778 pub const fn deposit_bits(self, mask: Self) -> Self {
779 imp::int_bits::$ActualT::deposit_impl(self as $ActualT, mask as $ActualT) as $SelfT
780 }
781
782 /// Reverses the order of bits in the integer. The least significant bit becomes the most significant bit,
783 /// second least-significant bit becomes second most-significant bit, etc.
784 ///
785 /// # Examples
786 ///
787 /// ```
788 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
789 /// let m = n.reverse_bits();
790 ///
791 #[doc = concat!("assert_eq!(m, ", $reversed, ");")]
792 #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
793 /// ```
794 #[stable(feature = "reverse_bits", since = "1.37.0")]
795 #[rustc_const_stable(feature = "reverse_bits", since = "1.37.0")]
796 #[must_use = "this returns the result of the operation, \
797 without modifying the original"]
798 #[inline(always)]
799 pub const fn reverse_bits(self) -> Self {
800 intrinsics::bitreverse(self as $ActualT) as Self
801 }
802
803 /// Converts an integer from big endian to the target's endianness.
804 ///
805 /// On big endian this is a no-op. On little endian the bytes are
806 /// swapped.
807 ///
808 /// # Examples
809 ///
810 /// ```
811 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
812 ///
813 /// if cfg!(target_endian = "big") {
814 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n)")]
815 /// } else {
816 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n.swap_bytes())")]
817 /// }
818 /// ```
819 #[stable(feature = "rust1", since = "1.0.0")]
820 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
821 #[must_use]
822 #[inline(always)]
823 pub const fn from_be(x: Self) -> Self {
824 cfg_select! {
825 target_endian = "big" => x,
826 _ => x.swap_bytes(),
827 }
828 }
829
830 /// Converts an integer from little endian to the target's endianness.
831 ///
832 /// On little endian this is a no-op. On big endian the bytes are
833 /// swapped.
834 ///
835 /// # Examples
836 ///
837 /// ```
838 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
839 ///
840 /// if cfg!(target_endian = "little") {
841 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n)")]
842 /// } else {
843 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n.swap_bytes())")]
844 /// }
845 /// ```
846 #[stable(feature = "rust1", since = "1.0.0")]
847 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
848 #[must_use]
849 #[inline(always)]
850 pub const fn from_le(x: Self) -> Self {
851 cfg_select! {
852 target_endian = "little" => x,
853 _ => x.swap_bytes(),
854 }
855 }
856
857 /// Converts `self` to big endian from the target's endianness.
858 ///
859 /// On big endian this is a no-op. On little endian the bytes are
860 /// swapped.
861 ///
862 /// # Examples
863 ///
864 /// ```
865 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
866 ///
867 /// if cfg!(target_endian = "big") {
868 /// assert_eq!(n.to_be(), n)
869 /// } else {
870 /// assert_eq!(n.to_be(), n.swap_bytes())
871 /// }
872 /// ```
873 #[stable(feature = "rust1", since = "1.0.0")]
874 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
875 #[must_use = "this returns the result of the operation, \
876 without modifying the original"]
877 #[inline(always)]
878 pub const fn to_be(self) -> Self { // or not to be?
879 cfg_select! {
880 target_endian = "big" => self,
881 _ => self.swap_bytes(),
882 }
883 }
884
885 /// Converts `self` to little endian from the target's endianness.
886 ///
887 /// On little endian this is a no-op. On big endian the bytes are
888 /// swapped.
889 ///
890 /// # Examples
891 ///
892 /// ```
893 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
894 ///
895 /// if cfg!(target_endian = "little") {
896 /// assert_eq!(n.to_le(), n)
897 /// } else {
898 /// assert_eq!(n.to_le(), n.swap_bytes())
899 /// }
900 /// ```
901 #[stable(feature = "rust1", since = "1.0.0")]
902 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
903 #[must_use = "this returns the result of the operation, \
904 without modifying the original"]
905 #[inline(always)]
906 pub const fn to_le(self) -> Self {
907 cfg_select! {
908 target_endian = "little" => self,
909 _ => self.swap_bytes(),
910 }
911 }
912
913 /// Checked integer addition. Computes `self + rhs`, returning `None`
914 /// if overflow occurred.
915 ///
916 /// # Examples
917 ///
918 /// ```
919 #[doc = concat!(
920 "assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(1), ",
921 "Some(", stringify!($SelfT), "::MAX - 1));"
922 )]
923 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(3), None);")]
924 /// ```
925 #[stable(feature = "rust1", since = "1.0.0")]
926 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
927 #[must_use = "this returns the result of the operation, \
928 without modifying the original"]
929 #[inline]
930 pub const fn checked_add(self, rhs: Self) -> Option<Self> {
931 // This used to use `overflowing_add`, but that means it ends up being
932 // a `wrapping_add`, losing some optimization opportunities. Notably,
933 // phrasing it this way helps `.checked_add(1)` optimize to a check
934 // against `MAX` and a `add nuw`.
935 // Per <https://github.com/rust-lang/rust/pull/124114#issuecomment-2066173305>,
936 // LLVM is happy to re-form the intrinsic later if useful.
937
938 if intrinsics::unlikely(intrinsics::add_with_overflow(self, rhs).1) {
939 None
940 } else {
941 // SAFETY: Just checked it doesn't overflow
942 Some(unsafe { intrinsics::unchecked_add(self, rhs) })
943 }
944 }
945
946 /// Strict integer addition. Computes `self + rhs`, panicking
947 /// if overflow occurred.
948 ///
949 /// # Panics
950 ///
951 /// ## Overflow behavior
952 ///
953 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
954 ///
955 /// # Examples
956 ///
957 /// ```
958 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).strict_add(1), ", stringify!($SelfT), "::MAX - 1);")]
959 /// ```
960 ///
961 /// The following panics because of overflow:
962 ///
963 /// ```should_panic
964 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add(3);")]
965 /// ```
966 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
967 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
968 #[must_use = "this returns the result of the operation, \
969 without modifying the original"]
970 #[inline]
971 #[track_caller]
972 pub const fn strict_add(self, rhs: Self) -> Self {
973 let (a, b) = self.overflowing_add(rhs);
974 if b { imp::overflow_panic::add() } else { a }
975 }
976
977 /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
978 /// cannot occur.
979 ///
980 /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
981 /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
982 ///
983 /// If you're just trying to avoid the panic in debug mode, then **do not**
984 /// use this. Instead, you're looking for [`wrapping_add`].
985 ///
986 /// # Safety
987 ///
988 /// This results in undefined behavior when
989 #[doc = concat!("`self + rhs > ", stringify!($SelfT), "::MAX`,")]
990 /// i.e. when [`checked_add`] would return `None`.
991 ///
992 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
993 #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
994 #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
995 #[stable(feature = "unchecked_math", since = "1.79.0")]
996 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
997 #[must_use = "this returns the result of the operation, \
998 without modifying the original"]
999 #[inline(always)]
1000 #[track_caller]
1001 pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
1002 assert_unsafe_precondition!(
1003 check_language_ub,
1004 concat!(stringify!($SelfT), "::unchecked_add cannot overflow"),
1005 (
1006 lhs: $SelfT = self,
1007 rhs: $SelfT = rhs,
1008 ) => !lhs.overflowing_add(rhs).1,
1009 );
1010
1011 // SAFETY: this is guaranteed to be safe by the caller.
1012 unsafe {
1013 intrinsics::unchecked_add(self, rhs)
1014 }
1015 }
1016
1017 /// Checked addition with a signed integer. Computes `self + rhs`,
1018 /// returning `None` if overflow occurred.
1019 ///
1020 /// # Examples
1021 ///
1022 /// ```
1023 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(2), Some(3));")]
1024 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(-2), None);")]
1025 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add_signed(3), None);")]
1026 /// ```
1027 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
1028 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
1029 #[must_use = "this returns the result of the operation, \
1030 without modifying the original"]
1031 #[inline]
1032 pub const fn checked_add_signed(self, rhs: $SignedT) -> Option<Self> {
1033 let (a, b) = self.overflowing_add_signed(rhs);
1034 if intrinsics::unlikely(b) { None } else { Some(a) }
1035 }
1036
1037 /// Strict addition with a signed integer. Computes `self + rhs`,
1038 /// panicking if overflow occurred.
1039 ///
1040 /// # Panics
1041 ///
1042 /// ## Overflow behavior
1043 ///
1044 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1045 ///
1046 /// # Examples
1047 ///
1048 /// ```
1049 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_add_signed(2), 3);")]
1050 /// ```
1051 ///
1052 /// The following panic because of overflow:
1053 ///
1054 /// ```should_panic
1055 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_add_signed(-2);")]
1056 /// ```
1057 ///
1058 /// ```should_panic
1059 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add_signed(3);")]
1060 /// ```
1061 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1062 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1063 #[must_use = "this returns the result of the operation, \
1064 without modifying the original"]
1065 #[inline]
1066 #[track_caller]
1067 pub const fn strict_add_signed(self, rhs: $SignedT) -> Self {
1068 let (a, b) = self.overflowing_add_signed(rhs);
1069 if b { imp::overflow_panic::add() } else { a }
1070 }
1071
1072 /// Checked integer subtraction. Computes `self - rhs`, returning
1073 /// `None` if overflow occurred.
1074 ///
1075 /// # Examples
1076 ///
1077 /// ```
1078 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub(1), Some(0));")]
1079 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_sub(1), None);")]
1080 /// ```
1081 #[stable(feature = "rust1", since = "1.0.0")]
1082 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1083 #[must_use = "this returns the result of the operation, \
1084 without modifying the original"]
1085 #[inline]
1086 pub const fn checked_sub(self, rhs: Self) -> Option<Self> {
1087 // Per PR#103299, there's no advantage to the `overflowing` intrinsic
1088 // for *unsigned* subtraction and we just emit the manual check anyway.
1089 // Thus, rather than using `overflowing_sub` that produces a wrapping
1090 // subtraction, check it ourself so we can use an unchecked one.
1091
1092 if self < rhs {
1093 None
1094 } else {
1095 // SAFETY: just checked this can't overflow
1096 Some(unsafe { intrinsics::unchecked_sub(self, rhs) })
1097 }
1098 }
1099
1100 /// Strict integer subtraction. Computes `self - rhs`, panicking if
1101 /// overflow occurred.
1102 ///
1103 /// # Panics
1104 ///
1105 /// ## Overflow behavior
1106 ///
1107 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1108 ///
1109 /// # Examples
1110 ///
1111 /// ```
1112 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_sub(1), 0);")]
1113 /// ```
1114 ///
1115 /// The following panics because of overflow:
1116 ///
1117 /// ```should_panic
1118 #[doc = concat!("let _ = 0", stringify!($SelfT), ".strict_sub(1);")]
1119 /// ```
1120 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1121 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1122 #[must_use = "this returns the result of the operation, \
1123 without modifying the original"]
1124 #[inline]
1125 #[track_caller]
1126 pub const fn strict_sub(self, rhs: Self) -> Self {
1127 let (a, b) = self.overflowing_sub(rhs);
1128 if b { imp::overflow_panic::sub() } else { a }
1129 }
1130
1131 /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
1132 /// cannot occur.
1133 ///
1134 /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
1135 /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
1136 ///
1137 /// If you're just trying to avoid the panic in debug mode, then **do not**
1138 /// use this. Instead, you're looking for [`wrapping_sub`].
1139 ///
1140 /// If you find yourself writing code like this:
1141 ///
1142 /// ```
1143 /// # let foo = 30_u32;
1144 /// # let bar = 20;
1145 /// if foo >= bar {
1146 /// // SAFETY: just checked it will not overflow
1147 /// let diff = unsafe { foo.unchecked_sub(bar) };
1148 /// // ... use diff ...
1149 /// }
1150 /// ```
1151 ///
1152 /// Consider changing it to
1153 ///
1154 /// ```
1155 /// # let foo = 30_u32;
1156 /// # let bar = 20;
1157 /// if let Some(diff) = foo.checked_sub(bar) {
1158 /// // ... use diff ...
1159 /// }
1160 /// ```
1161 ///
1162 /// As that does exactly the same thing -- including telling the optimizer
1163 /// that the subtraction cannot overflow -- but avoids needing `unsafe`.
1164 ///
1165 /// # Safety
1166 ///
1167 /// This results in undefined behavior when
1168 #[doc = concat!("`self - rhs < ", stringify!($SelfT), "::MIN`,")]
1169 /// i.e. when [`checked_sub`] would return `None`.
1170 ///
1171 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1172 #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
1173 #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
1174 #[stable(feature = "unchecked_math", since = "1.79.0")]
1175 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1176 #[must_use = "this returns the result of the operation, \
1177 without modifying the original"]
1178 #[inline(always)]
1179 #[track_caller]
1180 pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
1181 assert_unsafe_precondition!(
1182 check_language_ub,
1183 concat!(stringify!($SelfT), "::unchecked_sub cannot overflow"),
1184 (
1185 lhs: $SelfT = self,
1186 rhs: $SelfT = rhs,
1187 ) => !lhs.overflowing_sub(rhs).1,
1188 );
1189
1190 // SAFETY: this is guaranteed to be safe by the caller.
1191 unsafe {
1192 intrinsics::unchecked_sub(self, rhs)
1193 }
1194 }
1195
1196 /// Checked subtraction with a signed integer. Computes `self - rhs`,
1197 /// returning `None` if overflow occurred.
1198 ///
1199 /// # Examples
1200 ///
1201 /// ```
1202 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(2), None);")]
1203 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(-2), Some(3));")]
1204 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_sub_signed(-4), None);")]
1205 /// ```
1206 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1207 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1208 #[must_use = "this returns the result of the operation, \
1209 without modifying the original"]
1210 #[inline]
1211 pub const fn checked_sub_signed(self, rhs: $SignedT) -> Option<Self> {
1212 let (res, overflow) = self.overflowing_sub_signed(rhs);
1213
1214 if !overflow {
1215 Some(res)
1216 } else {
1217 None
1218 }
1219 }
1220
1221 /// Strict subtraction with a signed integer. Computes `self - rhs`,
1222 /// panicking if overflow occurred.
1223 ///
1224 /// # Panics
1225 ///
1226 /// ## Overflow behavior
1227 ///
1228 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1229 ///
1230 /// # Examples
1231 ///
1232 /// ```
1233 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".strict_sub_signed(2), 1);")]
1234 /// ```
1235 ///
1236 /// The following panic because of overflow:
1237 ///
1238 /// ```should_panic
1239 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_sub_signed(2);")]
1240 /// ```
1241 ///
1242 /// ```should_panic
1243 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX).strict_sub_signed(-1);")]
1244 /// ```
1245 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1246 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1247 #[must_use = "this returns the result of the operation, \
1248 without modifying the original"]
1249 #[inline]
1250 #[track_caller]
1251 pub const fn strict_sub_signed(self, rhs: $SignedT) -> Self {
1252 let (a, b) = self.overflowing_sub_signed(rhs);
1253 if b { imp::overflow_panic::sub() } else { a }
1254 }
1255
1256 #[doc = concat!(
1257 "Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
1258 stringify!($SignedT), "`], returning `None` if overflow occurred."
1259 )]
1260 ///
1261 /// # Examples
1262 ///
1263 /// ```
1264 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_signed_diff(2), Some(8));")]
1265 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_signed_diff(10), Some(-8));")]
1266 #[doc = concat!(
1267 "assert_eq!(",
1268 stringify!($SelfT),
1269 "::MAX.checked_signed_diff(",
1270 stringify!($SignedT),
1271 "::MAX as ",
1272 stringify!($SelfT),
1273 "), None);"
1274 )]
1275 #[doc = concat!(
1276 "assert_eq!((",
1277 stringify!($SignedT),
1278 "::MAX as ",
1279 stringify!($SelfT),
1280 ").checked_signed_diff(",
1281 stringify!($SelfT),
1282 "::MAX), Some(",
1283 stringify!($SignedT),
1284 "::MIN));"
1285 )]
1286 #[doc = concat!(
1287 "assert_eq!((",
1288 stringify!($SignedT),
1289 "::MAX as ",
1290 stringify!($SelfT),
1291 " + 1).checked_signed_diff(0), None);"
1292 )]
1293 #[doc = concat!(
1294 "assert_eq!(",
1295 stringify!($SelfT),
1296 "::MAX.checked_signed_diff(",
1297 stringify!($SelfT),
1298 "::MAX), Some(0));"
1299 )]
1300 /// ```
1301 #[stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1302 #[rustc_const_stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1303 #[inline]
1304 pub const fn checked_signed_diff(self, rhs: Self) -> Option<$SignedT> {
1305 let res = self.wrapping_sub(rhs) as $SignedT;
1306 let overflow = (self >= rhs) == (res < 0);
1307
1308 if !overflow {
1309 Some(res)
1310 } else {
1311 None
1312 }
1313 }
1314
1315 /// Checked integer multiplication. Computes `self * rhs`, returning
1316 /// `None` if overflow occurred.
1317 ///
1318 /// # Examples
1319 ///
1320 /// ```
1321 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_mul(1), Some(5));")]
1322 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_mul(2), None);")]
1323 /// ```
1324 #[stable(feature = "rust1", since = "1.0.0")]
1325 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1326 #[must_use = "this returns the result of the operation, \
1327 without modifying the original"]
1328 #[inline]
1329 pub const fn checked_mul(self, rhs: Self) -> Option<Self> {
1330 let (a, b) = self.overflowing_mul(rhs);
1331 if intrinsics::unlikely(b) { None } else { Some(a) }
1332 }
1333
1334 /// Strict integer multiplication. Computes `self * rhs`, panicking if
1335 /// overflow occurred.
1336 ///
1337 /// # Panics
1338 ///
1339 /// ## Overflow behavior
1340 ///
1341 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1342 ///
1343 /// # Examples
1344 ///
1345 /// ```
1346 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".strict_mul(1), 5);")]
1347 /// ```
1348 ///
1349 /// The following panics because of overflow:
1350 ///
1351 /// ``` should_panic
1352 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_mul(2);")]
1353 /// ```
1354 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1355 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1356 #[must_use = "this returns the result of the operation, \
1357 without modifying the original"]
1358 #[inline]
1359 #[track_caller]
1360 pub const fn strict_mul(self, rhs: Self) -> Self {
1361 let (a, b) = self.overflowing_mul(rhs);
1362 if b { imp::overflow_panic::mul() } else { a }
1363 }
1364
1365 /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
1366 /// cannot occur.
1367 ///
1368 /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
1369 /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
1370 ///
1371 /// If you're just trying to avoid the panic in debug mode, then **do not**
1372 /// use this. Instead, you're looking for [`wrapping_mul`].
1373 ///
1374 /// # Safety
1375 ///
1376 /// This results in undefined behavior when
1377 #[doc = concat!("`self * rhs > ", stringify!($SelfT), "::MAX`,")]
1378 /// i.e. when [`checked_mul`] would return `None`.
1379 ///
1380 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1381 #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
1382 #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
1383 #[stable(feature = "unchecked_math", since = "1.79.0")]
1384 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1385 #[must_use = "this returns the result of the operation, \
1386 without modifying the original"]
1387 #[inline(always)]
1388 #[track_caller]
1389 pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {
1390 assert_unsafe_precondition!(
1391 check_language_ub,
1392 concat!(stringify!($SelfT), "::unchecked_mul cannot overflow"),
1393 (
1394 lhs: $SelfT = self,
1395 rhs: $SelfT = rhs,
1396 ) => !lhs.overflowing_mul(rhs).1,
1397 );
1398
1399 // SAFETY: this is guaranteed to be safe by the caller.
1400 unsafe {
1401 intrinsics::unchecked_mul(self, rhs)
1402 }
1403 }
1404
1405 /// Checked integer division. Computes `self / rhs`, returning `None`
1406 /// if `rhs == 0`.
1407 ///
1408 /// # Examples
1409 ///
1410 /// ```
1411 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div(2), Some(64));")]
1412 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div(0), None);")]
1413 /// ```
1414 #[stable(feature = "rust1", since = "1.0.0")]
1415 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1416 #[must_use = "this returns the result of the operation, \
1417 without modifying the original"]
1418 #[inline]
1419 pub const fn checked_div(self, rhs: Self) -> Option<Self> {
1420 if intrinsics::unlikely(rhs == 0) {
1421 None
1422 } else {
1423 // SAFETY: div by zero has been checked above and unsigned types have no other
1424 // failure modes for division
1425 Some(unsafe { intrinsics::unchecked_div(self, rhs) })
1426 }
1427 }
1428
1429 /// Strict integer division. Computes `self / rhs`.
1430 ///
1431 /// Strict division on unsigned types is just normal division. There's no
1432 /// way overflow could ever happen. This function exists so that all
1433 /// operations are accounted for in the strict operations.
1434 ///
1435 /// # Panics
1436 ///
1437 /// This function will panic if `rhs` is zero.
1438 ///
1439 /// # Examples
1440 ///
1441 /// ```
1442 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div(10), 10);")]
1443 /// ```
1444 ///
1445 /// The following panics because of division by zero:
1446 ///
1447 /// ```should_panic
1448 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div(0);")]
1449 /// ```
1450 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1451 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1452 #[must_use = "this returns the result of the operation, \
1453 without modifying the original"]
1454 #[inline(always)]
1455 #[track_caller]
1456 pub const fn strict_div(self, rhs: Self) -> Self {
1457 self / rhs
1458 }
1459
1460 /// Checked Euclidean division. Computes `self.div_euclid(rhs)`, returning `None`
1461 /// if `rhs == 0`.
1462 ///
1463 /// # Examples
1464 ///
1465 /// ```
1466 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div_euclid(2), Some(64));")]
1467 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div_euclid(0), None);")]
1468 /// ```
1469 #[stable(feature = "euclidean_division", since = "1.38.0")]
1470 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1471 #[must_use = "this returns the result of the operation, \
1472 without modifying the original"]
1473 #[inline]
1474 pub const fn checked_div_euclid(self, rhs: Self) -> Option<Self> {
1475 if intrinsics::unlikely(rhs == 0) {
1476 None
1477 } else {
1478 Some(self.div_euclid(rhs))
1479 }
1480 }
1481
1482 /// Strict Euclidean division. Computes `self.div_euclid(rhs)`.
1483 ///
1484 /// Strict division on unsigned types is just normal division. There's no
1485 /// way overflow could ever happen. This function exists so that all
1486 /// operations are accounted for in the strict operations. Since, for the
1487 /// positive integers, all common definitions of division are equal, this
1488 /// is exactly equal to `self.strict_div(rhs)`.
1489 ///
1490 /// # Panics
1491 ///
1492 /// This function will panic if `rhs` is zero.
1493 ///
1494 /// # Examples
1495 ///
1496 /// ```
1497 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div_euclid(10), 10);")]
1498 /// ```
1499 /// The following panics because of division by zero:
1500 ///
1501 /// ```should_panic
1502 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div_euclid(0);")]
1503 /// ```
1504 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1505 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1506 #[must_use = "this returns the result of the operation, \
1507 without modifying the original"]
1508 #[inline(always)]
1509 #[track_caller]
1510 pub const fn strict_div_euclid(self, rhs: Self) -> Self {
1511 self / rhs
1512 }
1513
1514 /// Checked integer division without remainder. Computes `self / rhs`,
1515 /// returning `None` if `rhs == 0` or if `self % rhs != 0`.
1516 ///
1517 /// # Examples
1518 ///
1519 /// ```
1520 /// #![feature(exact_div)]
1521 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(2), Some(32));")]
1522 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(32), Some(2));")]
1523 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(0), None);")]
1524 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".checked_div_exact(2), None);")]
1525 /// ```
1526 #[unstable(
1527 feature = "exact_div",
1528 issue = "139911",
1529 )]
1530 #[must_use = "this returns the result of the operation, \
1531 without modifying the original"]
1532 #[inline]
1533 pub const fn checked_div_exact(self, rhs: Self) -> Option<Self> {
1534 if intrinsics::unlikely(rhs == 0) {
1535 None
1536 } else {
1537 // SAFETY: division by zero is checked above
1538 unsafe {
1539 if intrinsics::unlikely(intrinsics::unchecked_rem(self, rhs) != 0) {
1540 None
1541 } else {
1542 Some(intrinsics::exact_div(self, rhs))
1543 }
1544 }
1545 }
1546 }
1547
1548 /// Integer division without remainder. Computes `self / rhs`, returning `None` if `self % rhs != 0`.
1549 ///
1550 /// # Panics
1551 ///
1552 /// This function will panic if `rhs == 0`.
1553 ///
1554 /// # Examples
1555 ///
1556 /// ```
1557 /// #![feature(exact_div)]
1558 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(2), Some(32));")]
1559 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(32), Some(2));")]
1560 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".div_exact(2), None);")]
1561 /// ```
1562 #[unstable(
1563 feature = "exact_div",
1564 issue = "139911",
1565 )]
1566 #[must_use = "this returns the result of the operation, \
1567 without modifying the original"]
1568 #[inline]
1569 #[rustc_inherit_overflow_checks]
1570 pub const fn div_exact(self, rhs: Self) -> Option<Self> {
1571 if self % rhs != 0 {
1572 None
1573 } else {
1574 Some(self / rhs)
1575 }
1576 }
1577
1578 /// Unchecked integer division without remainder. Computes `self / rhs`.
1579 ///
1580 /// # Safety
1581 ///
1582 /// This results in undefined behavior when `rhs == 0` or `self % rhs != 0`,
1583 /// i.e. when [`checked_div_exact`](Self::checked_div_exact) would return `None`.
1584 #[unstable(
1585 feature = "exact_div",
1586 issue = "139911",
1587 )]
1588 #[must_use = "this returns the result of the operation, \
1589 without modifying the original"]
1590 #[inline]
1591 pub const unsafe fn unchecked_div_exact(self, rhs: Self) -> Self {
1592 assert_unsafe_precondition!(
1593 check_language_ub,
1594 concat!(stringify!($SelfT), "::unchecked_div_exact divide by zero or leave a remainder"),
1595 (
1596 lhs: $SelfT = self,
1597 rhs: $SelfT = rhs,
1598 ) => rhs > 0 && lhs % rhs == 0,
1599 );
1600 // SAFETY: Same precondition
1601 unsafe { intrinsics::exact_div(self, rhs) }
1602 }
1603
1604 /// Checked integer remainder. Computes `self % rhs`, returning `None`
1605 /// if `rhs == 0`.
1606 ///
1607 /// # Examples
1608 ///
1609 /// ```
1610 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(2), Some(1));")]
1611 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(0), None);")]
1612 /// ```
1613 #[stable(feature = "wrapping", since = "1.7.0")]
1614 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1615 #[must_use = "this returns the result of the operation, \
1616 without modifying the original"]
1617 #[inline]
1618 pub const fn checked_rem(self, rhs: Self) -> Option<Self> {
1619 if intrinsics::unlikely(rhs == 0) {
1620 None
1621 } else {
1622 // SAFETY: div by zero has been checked above and unsigned types have no other
1623 // failure modes for division
1624 Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
1625 }
1626 }
1627
1628 /// Strict integer remainder. Computes `self % rhs`.
1629 ///
1630 /// Strict remainder calculation on unsigned types is just the regular
1631 /// remainder calculation. There's no way overflow could ever happen.
1632 /// This function exists so that all operations are accounted for in the
1633 /// strict operations.
1634 ///
1635 /// # Panics
1636 ///
1637 /// This function will panic if `rhs` is zero.
1638 ///
1639 /// # Examples
1640 ///
1641 /// ```
1642 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem(10), 0);")]
1643 /// ```
1644 ///
1645 /// The following panics because of division by zero:
1646 ///
1647 /// ```should_panic
1648 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem(0);")]
1649 /// ```
1650 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1651 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1652 #[must_use = "this returns the result of the operation, \
1653 without modifying the original"]
1654 #[inline(always)]
1655 #[track_caller]
1656 pub const fn strict_rem(self, rhs: Self) -> Self {
1657 self % rhs
1658 }
1659
1660 /// Checked Euclidean modulo. Computes `self.rem_euclid(rhs)`, returning `None`
1661 /// if `rhs == 0`.
1662 ///
1663 /// # Examples
1664 ///
1665 /// ```
1666 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(2), Some(1));")]
1667 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(0), None);")]
1668 /// ```
1669 #[stable(feature = "euclidean_division", since = "1.38.0")]
1670 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1671 #[must_use = "this returns the result of the operation, \
1672 without modifying the original"]
1673 #[inline]
1674 pub const fn checked_rem_euclid(self, rhs: Self) -> Option<Self> {
1675 if intrinsics::unlikely(rhs == 0) {
1676 None
1677 } else {
1678 Some(self.rem_euclid(rhs))
1679 }
1680 }
1681
1682 /// Strict Euclidean modulo. Computes `self.rem_euclid(rhs)`.
1683 ///
1684 /// Strict modulo calculation on unsigned types is just the regular
1685 /// remainder calculation. There's no way overflow could ever happen.
1686 /// This function exists so that all operations are accounted for in the
1687 /// strict operations. Since, for the positive integers, all common
1688 /// definitions of division are equal, this is exactly equal to
1689 /// `self.strict_rem(rhs)`.
1690 ///
1691 /// # Panics
1692 ///
1693 /// This function will panic if `rhs` is zero.
1694 ///
1695 /// # Examples
1696 ///
1697 /// ```
1698 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem_euclid(10), 0);")]
1699 /// ```
1700 ///
1701 /// The following panics because of division by zero:
1702 ///
1703 /// ```should_panic
1704 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem_euclid(0);")]
1705 /// ```
1706 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1707 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1708 #[must_use = "this returns the result of the operation, \
1709 without modifying the original"]
1710 #[inline(always)]
1711 #[track_caller]
1712 pub const fn strict_rem_euclid(self, rhs: Self) -> Self {
1713 self % rhs
1714 }
1715
1716 /// Same value as `self | other`, but UB if any bit position is set in both inputs.
1717 ///
1718 /// This is a situational micro-optimization for places where you'd rather
1719 /// use addition on some platforms and bitwise or on other platforms, based
1720 /// on exactly which instructions combine better with whatever else you're
1721 /// doing. Note that there's no reason to bother using this for places
1722 /// where it's clear from the operations involved that they can't overlap.
1723 /// For example, if you're combining `u16`s into a `u32` with
1724 /// `((a as u32) << 16) | (b as u32)`, that's fine, as the backend will
1725 /// know those sides of the `|` are disjoint without needing help.
1726 ///
1727 /// # Examples
1728 ///
1729 /// ```
1730 /// #![feature(disjoint_bitor)]
1731 ///
1732 /// // SAFETY: `1` and `4` have no bits in common.
1733 /// unsafe {
1734 #[doc = concat!(" assert_eq!(1_", stringify!($SelfT), ".unchecked_disjoint_bitor(4), 5);")]
1735 /// }
1736 /// ```
1737 ///
1738 /// # Safety
1739 ///
1740 /// Requires that `(self & other) == 0`, otherwise it's immediate UB.
1741 ///
1742 /// Equivalently, requires that `(self | other) == (self + other)`.
1743 #[unstable(feature = "disjoint_bitor", issue = "135758")]
1744 #[rustc_const_unstable(feature = "disjoint_bitor", issue = "135758")]
1745 #[inline]
1746 pub const unsafe fn unchecked_disjoint_bitor(self, other: Self) -> Self {
1747 assert_unsafe_precondition!(
1748 check_language_ub,
1749 concat!(stringify!($SelfT), "::unchecked_disjoint_bitor cannot have overlapping bits"),
1750 (
1751 lhs: $SelfT = self,
1752 rhs: $SelfT = other,
1753 ) => (lhs & rhs) == 0,
1754 );
1755
1756 // SAFETY: Same precondition
1757 unsafe { intrinsics::disjoint_bitor(self, other) }
1758 }
1759
1760 /// Returns the logarithm of the number with respect to an arbitrary base,
1761 /// rounded down.
1762 ///
1763 /// This method might not be optimized owing to implementation details;
1764 /// [`ilog2`](Self::ilog2) can produce results more efficiently for base 2,
1765 /// and [`ilog10`](Self::ilog10) can produce results more efficiently for base 10.
1766 ///
1767 /// # Panics
1768 ///
1769 /// This function will panic if `self` is zero, or if `base` is less than 2.
1770 ///
1771 /// # Examples
1772 ///
1773 /// ```
1774 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".ilog(5), 1);")]
1775 /// ```
1776 #[stable(feature = "int_log", since = "1.67.0")]
1777 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1778 #[must_use = "this returns the result of the operation, \
1779 without modifying the original"]
1780 #[inline]
1781 #[track_caller]
1782 pub const fn ilog(self, base: Self) -> u32 {
1783 assert!(base >= 2, "base of integer logarithm must be at least 2");
1784 if let Some(log) = self.checked_ilog(base) {
1785 log
1786 } else {
1787 imp::int_log10::panic_for_nonpositive_argument()
1788 }
1789 }
1790
1791 /// Returns the base 2 logarithm of the number, rounded down.
1792 ///
1793 /// # Panics
1794 ///
1795 /// This function will panic if `self` is zero.
1796 ///
1797 /// # Examples
1798 ///
1799 /// ```
1800 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".ilog2(), 1);")]
1801 /// ```
1802 #[stable(feature = "int_log", since = "1.67.0")]
1803 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1804 #[must_use = "this returns the result of the operation, \
1805 without modifying the original"]
1806 #[inline]
1807 #[track_caller]
1808 pub const fn ilog2(self) -> u32 {
1809 if let Some(log) = self.checked_ilog2() {
1810 log
1811 } else {
1812 imp::int_log10::panic_for_nonpositive_argument()
1813 }
1814 }
1815
1816 /// Returns the base 10 logarithm of the number, rounded down.
1817 ///
1818 /// # Panics
1819 ///
1820 /// This function will panic if `self` is zero.
1821 ///
1822 /// # Example
1823 ///
1824 /// ```
1825 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".ilog10(), 1);")]
1826 /// ```
1827 #[stable(feature = "int_log", since = "1.67.0")]
1828 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1829 #[must_use = "this returns the result of the operation, \
1830 without modifying the original"]
1831 #[inline]
1832 #[track_caller]
1833 pub const fn ilog10(self) -> u32 {
1834 if let Some(log) = self.checked_ilog10() {
1835 log
1836 } else {
1837 imp::int_log10::panic_for_nonpositive_argument()
1838 }
1839 }
1840
1841 /// Returns the logarithm of the number with respect to an arbitrary base,
1842 /// rounded down.
1843 ///
1844 /// Returns `None` if the number is zero, or if the base is not at least 2.
1845 ///
1846 /// This method might not be optimized owing to implementation details;
1847 /// `checked_ilog2` can produce results more efficiently for base 2, and
1848 /// `checked_ilog10` can produce results more efficiently for base 10.
1849 ///
1850 /// # Examples
1851 ///
1852 /// ```
1853 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(5), Some(1));")]
1854 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".checked_ilog(5), Some(0));")]
1855 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(0), None);")]
1856 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(1), None);")]
1857 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_ilog(1), None);")]
1858 /// ```
1859 #[stable(feature = "int_log", since = "1.67.0")]
1860 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1861 #[must_use = "this returns the result of the operation, \
1862 without modifying the original"]
1863 #[inline]
1864 pub const fn checked_ilog(self, base: Self) -> Option<u32> {
1865 // Inform compiler of optimizations when the base is known at
1866 // compile time and there's a cheaper method available.
1867 //
1868 // Note: Like all optimizations, this is not guaranteed to be
1869 // applied by the compiler. If you want those specific bases,
1870 // use `.checked_ilog2()` or `.checked_ilog10()` directly.
1871 if core::intrinsics::is_val_statically_known(base) {
1872 // change of base:
1873 // if base == 2 ** k, then
1874 // log(base, n) == log(2, n) / k
1875 if base.is_power_of_two() && base > 1 {
1876 let k = base.ilog2();
1877 return Some(try_opt!(self.checked_ilog2()) / k);
1878 }
1879 if base == 10 {
1880 return self.checked_ilog10();
1881 }
1882 }
1883
1884 if self <= 0 || base <= 1 {
1885 None
1886 } else if self < base {
1887 Some(0)
1888 } else {
1889 // Since base >= self, n >= 1
1890 let mut n = 1;
1891 let mut r = base;
1892
1893 // Optimization for 128 bit wide integers.
1894 if Self::BITS == 128 {
1895 // The following is a correct lower bound for ⌊log(base,self)⌋ because
1896 //
1897 // log(base,self) = log(2,self) / log(2,base)
1898 // ≥ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1)
1899 //
1900 // hence
1901 //
1902 // ⌊log(base,self)⌋ ≥ ⌊ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1) ⌋ .
1903 n = self.ilog2() / (base.ilog2() + 1);
1904 r = base.pow(n);
1905 }
1906
1907 while r <= self / base {
1908 n += 1;
1909 r *= base;
1910 }
1911 Some(n)
1912 }
1913 }
1914
1915 /// Returns the base 2 logarithm of the number, rounded down.
1916 ///
1917 /// Returns `None` if the number is zero.
1918 ///
1919 /// Note that this is equivalent to [`highest_one`](Self::highest_one).
1920 ///
1921 /// # Examples
1922 ///
1923 /// ```
1924 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_ilog2(), Some(1));")]
1925 /// ```
1926 #[stable(feature = "int_log", since = "1.67.0")]
1927 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1928 #[must_use = "this returns the result of the operation, \
1929 without modifying the original"]
1930 #[inline]
1931 pub const fn checked_ilog2(self) -> Option<u32> {
1932 match NonZero::new(self) {
1933 Some(x) => Some(x.ilog2()),
1934 None => None,
1935 }
1936 }
1937
1938 /// Returns the base 10 logarithm of the number, rounded down.
1939 ///
1940 /// Returns `None` if the number is zero.
1941 ///
1942 /// # Examples
1943 ///
1944 /// ```
1945 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_ilog10(), Some(1));")]
1946 /// ```
1947 #[stable(feature = "int_log", since = "1.67.0")]
1948 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1949 #[must_use = "this returns the result of the operation, \
1950 without modifying the original"]
1951 #[inline]
1952 pub const fn checked_ilog10(self) -> Option<u32> {
1953 match NonZero::new(self) {
1954 Some(x) => Some(x.ilog10()),
1955 None => None,
1956 }
1957 }
1958
1959 /// Checked negation. Computes `-self`, returning `None` unless `self ==
1960 /// 0`.
1961 ///
1962 /// Note that negating any positive integer will overflow.
1963 ///
1964 /// # Examples
1965 ///
1966 /// ```
1967 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_neg(), Some(0));")]
1968 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_neg(), None);")]
1969 /// ```
1970 #[stable(feature = "wrapping", since = "1.7.0")]
1971 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1972 #[must_use = "this returns the result of the operation, \
1973 without modifying the original"]
1974 #[inline]
1975 pub const fn checked_neg(self) -> Option<Self> {
1976 let (a, b) = self.overflowing_neg();
1977 if intrinsics::unlikely(b) { None } else { Some(a) }
1978 }
1979
1980 /// Strict negation. Computes `-self`, panicking unless `self ==
1981 /// 0`.
1982 ///
1983 /// Note that negating any positive integer will overflow.
1984 ///
1985 /// # Panics
1986 ///
1987 /// ## Overflow behavior
1988 ///
1989 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1990 ///
1991 /// # Examples
1992 ///
1993 /// ```
1994 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".strict_neg(), 0);")]
1995 /// ```
1996 ///
1997 /// The following panics because of overflow:
1998 ///
1999 /// ```should_panic
2000 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_neg();")]
2001 /// ```
2002 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2003 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2004 #[must_use = "this returns the result of the operation, \
2005 without modifying the original"]
2006 #[inline]
2007 #[track_caller]
2008 pub const fn strict_neg(self) -> Self {
2009 let (a, b) = self.overflowing_neg();
2010 if b { imp::overflow_panic::neg() } else { a }
2011 }
2012
2013 /// Checked shift left. Computes `self << rhs`, returning `None`
2014 /// if `rhs` is larger than or equal to the number of bits in `self`.
2015 ///
2016 /// # Examples
2017 ///
2018 /// ```
2019 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".checked_shl(4), Some(0x10));")]
2020 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(129), None);")]
2021 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(", stringify!($BITS_MINUS_ONE), "), Some(0));")]
2022 /// ```
2023 #[stable(feature = "wrapping", since = "1.7.0")]
2024 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2025 #[must_use = "this returns the result of the operation, \
2026 without modifying the original"]
2027 #[inline]
2028 pub const fn checked_shl(self, rhs: u32) -> Option<Self> {
2029 // Not using overflowing_shl as that's a wrapping shift
2030 if rhs < Self::BITS {
2031 // SAFETY: just checked the RHS is in-range
2032 Some(unsafe { self.unchecked_shl(rhs) })
2033 } else {
2034 None
2035 }
2036 }
2037
2038 /// Strict shift left. Computes `self << rhs`, panicking if `rhs` is larger
2039 /// than or equal to the number of bits in `self`.
2040 ///
2041 /// # Panics
2042 ///
2043 /// ## Overflow behavior
2044 ///
2045 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2046 ///
2047 /// # Examples
2048 ///
2049 /// ```
2050 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".strict_shl(4), 0x10);")]
2051 /// ```
2052 ///
2053 /// The following panics because of overflow:
2054 ///
2055 /// ```should_panic
2056 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shl(129);")]
2057 /// ```
2058 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2059 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2060 #[must_use = "this returns the result of the operation, \
2061 without modifying the original"]
2062 #[inline]
2063 #[track_caller]
2064 pub const fn strict_shl(self, rhs: u32) -> Self {
2065 let (a, b) = self.overflowing_shl(rhs);
2066 if b { imp::overflow_panic::shl() } else { a }
2067 }
2068
2069 /// Unchecked shift left. Computes `self << rhs`, assuming that
2070 /// `rhs` is less than the number of bits in `self`.
2071 ///
2072 /// # Safety
2073 ///
2074 /// This results in undefined behavior if `rhs` is larger than
2075 /// or equal to the number of bits in `self`,
2076 /// i.e. when [`checked_shl`] would return `None`.
2077 ///
2078 #[doc = concat!("[`checked_shl`]: ", stringify!($SelfT), "::checked_shl")]
2079 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2080 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2081 #[must_use = "this returns the result of the operation, \
2082 without modifying the original"]
2083 #[inline(always)]
2084 #[track_caller]
2085 pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self {
2086 assert_unsafe_precondition!(
2087 check_language_ub,
2088 concat!(stringify!($SelfT), "::unchecked_shl cannot overflow"),
2089 (
2090 rhs: u32 = rhs,
2091 ) => rhs < <$ActualT>::BITS,
2092 );
2093
2094 // SAFETY: this is guaranteed to be safe by the caller.
2095 unsafe {
2096 intrinsics::unchecked_shl(self, rhs)
2097 }
2098 }
2099
2100 /// Unbounded shift left. Computes `self << rhs`, without bounding the value of `rhs`.
2101 ///
2102 /// If `rhs` is larger or equal to the number of bits in `self`,
2103 /// the entire value is shifted out, and `0` is returned.
2104 ///
2105 /// # Examples
2106 ///
2107 /// ```
2108 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(4), 0x10);")]
2109 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(129), 0);")]
2110 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(0), 0b101);")]
2111 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(1), 0b1010);")]
2112 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(2), 0b10100);")]
2113 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(", stringify!($BITS), "), 0);")]
2114 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(1).unbounded_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2115 ///
2116 #[doc = concat!("let start : ", stringify!($SelfT), " = 13;")]
2117 /// let mut running = start;
2118 /// for i in 0..160 {
2119 /// // The unbounded shift left by i is the same as `<< 1` i times
2120 /// assert_eq!(running, start.unbounded_shl(i));
2121 /// // Which is not always the case for a wrapping shift
2122 #[doc = concat!(" assert_eq!(running == start.wrapping_shl(i), i < ", stringify!($BITS), ");")]
2123 ///
2124 /// running <<= 1;
2125 /// }
2126 /// ```
2127 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2128 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2129 #[must_use = "this returns the result of the operation, \
2130 without modifying the original"]
2131 #[inline]
2132 pub const fn unbounded_shl(self, rhs: u32) -> $SelfT{
2133 if rhs < Self::BITS {
2134 // SAFETY:
2135 // rhs is just checked to be in-range above
2136 unsafe { self.unchecked_shl(rhs) }
2137 } else {
2138 0
2139 }
2140 }
2141
2142 /// Exact shift left. Computes `self << rhs` as long as it can be reversed losslessly.
2143 ///
2144 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2145 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2146 /// Otherwise, returns `Some(self << rhs)`.
2147 ///
2148 /// # Examples
2149 ///
2150 /// ```
2151 /// #![feature(exact_bitshifts)]
2152 ///
2153 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(4), Some(0x10));")]
2154 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(129), None);")]
2155 /// ```
2156 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2157 #[must_use = "this returns the result of the operation, \
2158 without modifying the original"]
2159 #[inline]
2160 pub const fn shl_exact(self, rhs: u32) -> Option<$SelfT> {
2161 if rhs <= self.leading_zeros() && rhs < <$SelfT>::BITS {
2162 // SAFETY: rhs is checked above
2163 Some(unsafe { self.unchecked_shl(rhs) })
2164 } else {
2165 None
2166 }
2167 }
2168
2169 /// Unchecked exact shift left. Computes `self << rhs`, assuming the operation can be
2170 /// losslessly reversed `rhs` cannot be larger than
2171 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2172 ///
2173 /// # Safety
2174 ///
2175 /// This results in undefined behavior when `rhs > self.leading_zeros() || rhs >=
2176 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2177 /// i.e. when
2178 #[doc = concat!("[`", stringify!($SelfT), "::shl_exact`]")]
2179 /// would return `None`.
2180 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2181 #[must_use = "this returns the result of the operation, \
2182 without modifying the original"]
2183 #[inline]
2184 pub const unsafe fn unchecked_shl_exact(self, rhs: u32) -> $SelfT {
2185 assert_unsafe_precondition!(
2186 check_library_ub,
2187 concat!(stringify!($SelfT), "::unchecked_shl_exact cannot shift out non-zero bits"),
2188 (
2189 zeros: u32 = self.leading_zeros(),
2190 bits: u32 = <$SelfT>::BITS,
2191 rhs: u32 = rhs,
2192 ) => rhs <= zeros && rhs < bits,
2193 );
2194
2195 // SAFETY: this is guaranteed to be safe by the caller
2196 unsafe { self.unchecked_shl(rhs) }
2197 }
2198
2199 /// Checked shift right. Computes `self >> rhs`, returning `None`
2200 /// if `rhs` is larger than or equal to the number of bits in `self`.
2201 ///
2202 /// # Examples
2203 ///
2204 /// ```
2205 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(4), Some(0x1));")]
2206 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(129), None);")]
2207 /// ```
2208 #[stable(feature = "wrapping", since = "1.7.0")]
2209 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2210 #[must_use = "this returns the result of the operation, \
2211 without modifying the original"]
2212 #[inline]
2213 pub const fn checked_shr(self, rhs: u32) -> Option<Self> {
2214 // Not using overflowing_shr as that's a wrapping shift
2215 if rhs < Self::BITS {
2216 // SAFETY: just checked the RHS is in-range
2217 Some(unsafe { self.unchecked_shr(rhs) })
2218 } else {
2219 None
2220 }
2221 }
2222
2223 /// Strict shift right. Computes `self >> rhs`, panicking if `rhs` is
2224 /// larger than or equal to the number of bits in `self`.
2225 ///
2226 /// # Panics
2227 ///
2228 /// ## Overflow behavior
2229 ///
2230 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2231 ///
2232 /// # Examples
2233 ///
2234 /// ```
2235 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".strict_shr(4), 0x1);")]
2236 /// ```
2237 ///
2238 /// The following panics because of overflow:
2239 ///
2240 /// ```should_panic
2241 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shr(129);")]
2242 /// ```
2243 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2244 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2245 #[must_use = "this returns the result of the operation, \
2246 without modifying the original"]
2247 #[inline]
2248 #[track_caller]
2249 pub const fn strict_shr(self, rhs: u32) -> Self {
2250 let (a, b) = self.overflowing_shr(rhs);
2251 if b { imp::overflow_panic::shr() } else { a }
2252 }
2253
2254 /// Unchecked shift right. Computes `self >> rhs`, assuming that
2255 /// `rhs` is less than the number of bits in `self`.
2256 ///
2257 /// # Safety
2258 ///
2259 /// This results in undefined behavior if `rhs` is larger than
2260 /// or equal to the number of bits in `self`,
2261 /// i.e. when [`checked_shr`] would return `None`.
2262 ///
2263 #[doc = concat!("[`checked_shr`]: ", stringify!($SelfT), "::checked_shr")]
2264 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2265 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2266 #[must_use = "this returns the result of the operation, \
2267 without modifying the original"]
2268 #[inline(always)]
2269 #[track_caller]
2270 pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self {
2271 assert_unsafe_precondition!(
2272 check_language_ub,
2273 concat!(stringify!($SelfT), "::unchecked_shr cannot overflow"),
2274 (
2275 rhs: u32 = rhs,
2276 ) => rhs < <$ActualT>::BITS,
2277 );
2278
2279 // SAFETY: this is guaranteed to be safe by the caller.
2280 unsafe {
2281 intrinsics::unchecked_shr(self, rhs)
2282 }
2283 }
2284
2285 /// Unbounded shift right. Computes `self >> rhs`, without bounding the value of `rhs`.
2286 ///
2287 /// If `rhs` is larger or equal to the number of bits in `self`,
2288 /// the entire value is shifted out, and `0` is returned.
2289 ///
2290 /// # Examples
2291 ///
2292 /// ```
2293 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(4), 0x1);")]
2294 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(129), 0);")]
2295 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(0), 0b1010);")]
2296 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(1), 0b101);")]
2297 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(2), 0b10);")]
2298 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(", stringify!($BITS), "), 0);")]
2299 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(1).unbounded_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2300 ///
2301 #[doc = concat!("let start = ", stringify!($SelfT), "::rotate_right(13, 4);")]
2302 /// let mut running = start;
2303 /// for i in 0..160 {
2304 /// // The unbounded shift right by i is the same as `>> 1` i times
2305 /// assert_eq!(running, start.unbounded_shr(i));
2306 /// // Which is not always the case for a wrapping shift
2307 #[doc = concat!(" assert_eq!(running == start.wrapping_shr(i), i < ", stringify!($BITS), ");")]
2308 ///
2309 /// running >>= 1;
2310 /// }
2311 /// ```
2312 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2313 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2314 #[must_use = "this returns the result of the operation, \
2315 without modifying the original"]
2316 #[inline]
2317 pub const fn unbounded_shr(self, rhs: u32) -> $SelfT{
2318 if rhs < Self::BITS {
2319 // SAFETY:
2320 // rhs is just checked to be in-range above
2321 unsafe { self.unchecked_shr(rhs) }
2322 } else {
2323 0
2324 }
2325 }
2326
2327 /// Exact shift right. Computes `self >> rhs` as long as it can be reversed losslessly.
2328 ///
2329 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2330 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2331 /// Otherwise, returns `Some(self >> rhs)`.
2332 ///
2333 /// # Examples
2334 ///
2335 /// ```
2336 /// #![feature(exact_bitshifts)]
2337 ///
2338 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(4), Some(0x1));")]
2339 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(5), None);")]
2340 /// ```
2341 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2342 #[must_use = "this returns the result of the operation, \
2343 without modifying the original"]
2344 #[inline]
2345 pub const fn shr_exact(self, rhs: u32) -> Option<$SelfT> {
2346 if rhs <= self.trailing_zeros() && rhs < <$SelfT>::BITS {
2347 // SAFETY: rhs is checked above
2348 Some(unsafe { self.unchecked_shr(rhs) })
2349 } else {
2350 None
2351 }
2352 }
2353
2354 /// Unchecked exact shift right. Computes `self >> rhs`, assuming the operation can be
2355 /// losslessly reversed and `rhs` cannot be larger than
2356 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2357 ///
2358 /// # Safety
2359 ///
2360 /// This results in undefined behavior when `rhs > self.trailing_zeros() || rhs >=
2361 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2362 /// i.e. when
2363 #[doc = concat!("[`", stringify!($SelfT), "::shr_exact`]")]
2364 /// would return `None`.
2365 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2366 #[must_use = "this returns the result of the operation, \
2367 without modifying the original"]
2368 #[inline]
2369 pub const unsafe fn unchecked_shr_exact(self, rhs: u32) -> $SelfT {
2370 assert_unsafe_precondition!(
2371 check_library_ub,
2372 concat!(stringify!($SelfT), "::unchecked_shr_exact cannot shift out non-zero bits"),
2373 (
2374 zeros: u32 = self.trailing_zeros(),
2375 bits: u32 = <$SelfT>::BITS,
2376 rhs: u32 = rhs,
2377 ) => rhs <= zeros && rhs < bits,
2378 );
2379
2380 // SAFETY: this is guaranteed to be safe by the caller
2381 unsafe { self.unchecked_shr(rhs) }
2382 }
2383
2384 /// Checked exponentiation. Computes `self.pow(exp)`, returning `None` if
2385 /// overflow occurred.
2386 ///
2387 /// # Examples
2388 ///
2389 /// ```
2390 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_pow(5), Some(32));")]
2391 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
2392 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
2393 /// ```
2394 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2395 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2396 #[must_use = "this returns the result of the operation, \
2397 without modifying the original"]
2398 #[inline]
2399 pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
2400 let mut base = self;
2401 let mut acc: Self = 1;
2402
2403 if intrinsics::is_val_statically_known(base) && base.is_power_of_two() {
2404 // change of base:
2405 // if base == 2 ** k, then
2406 // (2 ** k) ** n
2407 // == 2 ** (k * n)
2408 // == 1 << (k * n)
2409 let k = base.ilog2();
2410 let shift = try_opt!(k.checked_mul(exp));
2411 return (1 as Self).checked_shl(shift);
2412 }
2413
2414 if exp == 0 {
2415 return Some(1);
2416 }
2417
2418 if intrinsics::is_val_statically_known(exp) {
2419 while exp > 1 {
2420 if (exp & 1) == 1 {
2421 acc = try_opt!(acc.checked_mul(base));
2422 }
2423 exp /= 2;
2424 base = try_opt!(base.checked_mul(base));
2425 }
2426
2427 // since exp!=0, finally the exp must be 1.
2428 // Deal with the final bit of the exponent separately, since
2429 // squaring the base afterwards is not necessary and may cause a
2430 // needless overflow.
2431 return acc.checked_mul(base);
2432 }
2433
2434 loop {
2435 if (exp & 1) == 1 {
2436 acc = try_opt!(acc.checked_mul(base));
2437 // since exp!=0, finally the exp must be 1.
2438 if exp == 1 {
2439 return Some(acc);
2440 }
2441 }
2442 exp /= 2;
2443 base = try_opt!(base.checked_mul(base));
2444 }
2445 }
2446
2447 /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
2448 /// overflow occurred.
2449 ///
2450 /// # Panics
2451 ///
2452 /// ## Overflow behavior
2453 ///
2454 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2455 ///
2456 /// # Examples
2457 ///
2458 /// ```
2459 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".strict_pow(5), 32);")]
2460 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(0), 1);")]
2461 /// ```
2462 ///
2463 /// The following panics because of overflow:
2464 ///
2465 /// ```should_panic
2466 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_pow(2);")]
2467 /// ```
2468 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2469 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2470 #[must_use = "this returns the result of the operation, \
2471 without modifying the original"]
2472 #[inline]
2473 #[track_caller]
2474 pub const fn strict_pow(self, exp: u32) -> Self {
2475 match self.checked_pow(exp) {
2476 None => imp::overflow_panic::pow(),
2477 Some(a) => a,
2478 }
2479 }
2480
2481 /// Saturating integer addition. Computes `self + rhs`, saturating at
2482 /// the numeric bounds instead of overflowing.
2483 ///
2484 /// # Examples
2485 ///
2486 /// ```
2487 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_add(1), 101);")]
2488 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_add(127), ", stringify!($SelfT), "::MAX);")]
2489 /// ```
2490 #[stable(feature = "rust1", since = "1.0.0")]
2491 #[must_use = "this returns the result of the operation, \
2492 without modifying the original"]
2493 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2494 #[inline(always)]
2495 pub const fn saturating_add(self, rhs: Self) -> Self {
2496 intrinsics::saturating_add(self, rhs)
2497 }
2498
2499 /// Saturating addition with a signed integer. Computes `self + rhs`,
2500 /// saturating at the numeric bounds instead of overflowing.
2501 ///
2502 /// # Examples
2503 ///
2504 /// ```
2505 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(2), 3);")]
2506 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(-2), 0);")]
2507 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_add_signed(4), ", stringify!($SelfT), "::MAX);")]
2508 /// ```
2509 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2510 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2511 #[must_use = "this returns the result of the operation, \
2512 without modifying the original"]
2513 #[inline]
2514 pub const fn saturating_add_signed(self, rhs: $SignedT) -> Self {
2515 let (res, overflow) = self.overflowing_add(rhs as Self);
2516 if overflow == (rhs < 0) {
2517 res
2518 } else if overflow {
2519 Self::MAX
2520 } else {
2521 0
2522 }
2523 }
2524
2525 /// Saturating integer subtraction. Computes `self - rhs`, saturating
2526 /// at the numeric bounds instead of overflowing.
2527 ///
2528 /// # Examples
2529 ///
2530 /// ```
2531 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_sub(27), 73);")]
2532 #[doc = concat!("assert_eq!(13", stringify!($SelfT), ".saturating_sub(127), 0);")]
2533 /// ```
2534 #[stable(feature = "rust1", since = "1.0.0")]
2535 #[must_use = "this returns the result of the operation, \
2536 without modifying the original"]
2537 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2538 #[inline(always)]
2539 pub const fn saturating_sub(self, rhs: Self) -> Self {
2540 intrinsics::saturating_sub(self, rhs)
2541 }
2542
2543 /// Saturating integer subtraction. Computes `self` - `rhs`, saturating at
2544 /// the numeric bounds instead of overflowing.
2545 ///
2546 /// # Examples
2547 ///
2548 /// ```
2549 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(2), 0);")]
2550 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(-2), 3);")]
2551 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_sub_signed(-4), ", stringify!($SelfT), "::MAX);")]
2552 /// ```
2553 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2554 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2555 #[must_use = "this returns the result of the operation, \
2556 without modifying the original"]
2557 #[inline]
2558 pub const fn saturating_sub_signed(self, rhs: $SignedT) -> Self {
2559 let (res, overflow) = self.overflowing_sub_signed(rhs);
2560
2561 if !overflow {
2562 res
2563 } else if rhs < 0 {
2564 Self::MAX
2565 } else {
2566 0
2567 }
2568 }
2569
2570 /// Saturating integer multiplication. Computes `self * rhs`,
2571 /// saturating at the numeric bounds instead of overflowing.
2572 ///
2573 /// # Examples
2574 ///
2575 /// ```
2576 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".saturating_mul(10), 20);")]
2577 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX).saturating_mul(10), ", stringify!($SelfT),"::MAX);")]
2578 /// ```
2579 #[stable(feature = "wrapping", since = "1.7.0")]
2580 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2581 #[must_use = "this returns the result of the operation, \
2582 without modifying the original"]
2583 #[inline]
2584 pub const fn saturating_mul(self, rhs: Self) -> Self {
2585 match self.checked_mul(rhs) {
2586 Some(x) => x,
2587 None => Self::MAX,
2588 }
2589 }
2590
2591 /// Saturating integer division. Computes `self / rhs`, saturating at the
2592 /// numeric bounds instead of overflowing.
2593 ///
2594 /// # Panics
2595 ///
2596 /// This function will panic if `rhs` is zero.
2597 ///
2598 /// # Examples
2599 ///
2600 /// ```
2601 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".saturating_div(2), 2);")]
2602 ///
2603 /// ```
2604 #[stable(feature = "saturating_div", since = "1.58.0")]
2605 #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
2606 #[must_use = "this returns the result of the operation, \
2607 without modifying the original"]
2608 #[inline]
2609 #[track_caller]
2610 pub const fn saturating_div(self, rhs: Self) -> Self {
2611 // on unsigned types, there is no overflow in integer division
2612 self.wrapping_div(rhs)
2613 }
2614
2615 /// Saturating integer exponentiation. Computes `self.pow(exp)`,
2616 /// saturating at the numeric bounds instead of overflowing.
2617 ///
2618 /// # Examples
2619 ///
2620 /// ```
2621 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".saturating_pow(3), 64);")]
2622 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(0), 1);")]
2623 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
2624 /// ```
2625 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2626 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2627 #[must_use = "this returns the result of the operation, \
2628 without modifying the original"]
2629 #[inline]
2630 pub const fn saturating_pow(self, exp: u32) -> Self {
2631 match self.checked_pow(exp) {
2632 Some(x) => x,
2633 None => Self::MAX,
2634 }
2635 }
2636
2637 /// Wrapping (modular) addition. Computes `self + rhs`,
2638 /// wrapping around at the boundary of the type.
2639 ///
2640 /// # Examples
2641 ///
2642 /// ```
2643 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(55), 255);")]
2644 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::MAX), 199);")]
2645 /// ```
2646 #[stable(feature = "rust1", since = "1.0.0")]
2647 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2648 #[must_use = "this returns the result of the operation, \
2649 without modifying the original"]
2650 #[inline(always)]
2651 pub const fn wrapping_add(self, rhs: Self) -> Self {
2652 intrinsics::wrapping_add(self, rhs)
2653 }
2654
2655 /// Wrapping (modular) addition with a signed integer. Computes
2656 /// `self + rhs`, wrapping around at the boundary of the type.
2657 ///
2658 /// # Examples
2659 ///
2660 /// ```
2661 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(2), 3);")]
2662 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(-2), ", stringify!($SelfT), "::MAX);")]
2663 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_add_signed(4), 1);")]
2664 /// ```
2665 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2666 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2667 #[must_use = "this returns the result of the operation, \
2668 without modifying the original"]
2669 #[inline]
2670 pub const fn wrapping_add_signed(self, rhs: $SignedT) -> Self {
2671 self.wrapping_add(rhs as Self)
2672 }
2673
2674 /// Wrapping (modular) subtraction. Computes `self - rhs`,
2675 /// wrapping around at the boundary of the type.
2676 ///
2677 /// # Examples
2678 ///
2679 /// ```
2680 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(100), 0);")]
2681 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::MAX), 101);")]
2682 /// ```
2683 #[stable(feature = "rust1", since = "1.0.0")]
2684 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2685 #[must_use = "this returns the result of the operation, \
2686 without modifying the original"]
2687 #[inline(always)]
2688 pub const fn wrapping_sub(self, rhs: Self) -> Self {
2689 intrinsics::wrapping_sub(self, rhs)
2690 }
2691
2692 /// Wrapping (modular) subtraction with a signed integer. Computes
2693 /// `self - rhs`, wrapping around at the boundary of the type.
2694 ///
2695 /// # Examples
2696 ///
2697 /// ```
2698 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(2), ", stringify!($SelfT), "::MAX);")]
2699 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(-2), 3);")]
2700 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_sub_signed(-4), 1);")]
2701 /// ```
2702 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2703 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2704 #[must_use = "this returns the result of the operation, \
2705 without modifying the original"]
2706 #[inline]
2707 pub const fn wrapping_sub_signed(self, rhs: $SignedT) -> Self {
2708 self.wrapping_sub(rhs as Self)
2709 }
2710
2711 /// Wrapping (modular) multiplication. Computes `self *
2712 /// rhs`, wrapping around at the boundary of the type.
2713 ///
2714 /// # Examples
2715 ///
2716 /// Please note that this example is shared among integer types, which is why `u8` is used.
2717 ///
2718 /// ```
2719 /// assert_eq!(10u8.wrapping_mul(12), 120);
2720 /// assert_eq!(25u8.wrapping_mul(12), 44);
2721 /// ```
2722 #[stable(feature = "rust1", since = "1.0.0")]
2723 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2724 #[must_use = "this returns the result of the operation, \
2725 without modifying the original"]
2726 #[inline(always)]
2727 pub const fn wrapping_mul(self, rhs: Self) -> Self {
2728 intrinsics::wrapping_mul(self, rhs)
2729 }
2730
2731 /// Wrapping (modular) division. Computes `self / rhs`.
2732 ///
2733 /// Wrapped division on unsigned types is just normal division. There's
2734 /// no way wrapping could ever happen. This function exists so that all
2735 /// operations are accounted for in the wrapping operations.
2736 ///
2737 /// # Panics
2738 ///
2739 /// This function will panic if `rhs` is zero.
2740 ///
2741 /// # Examples
2742 ///
2743 /// ```
2744 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div(10), 10);")]
2745 /// ```
2746 #[stable(feature = "num_wrapping", since = "1.2.0")]
2747 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2748 #[must_use = "this returns the result of the operation, \
2749 without modifying the original"]
2750 #[inline(always)]
2751 #[track_caller]
2752 pub const fn wrapping_div(self, rhs: Self) -> Self {
2753 self / rhs
2754 }
2755
2756 /// Wrapping Euclidean division. Computes `self.div_euclid(rhs)`.
2757 ///
2758 /// Wrapped division on unsigned types is just normal division. There's
2759 /// no way wrapping could ever happen. This function exists so that all
2760 /// operations are accounted for in the wrapping operations. Since, for
2761 /// the positive integers, all common definitions of division are equal,
2762 /// this is exactly equal to `self.wrapping_div(rhs)`.
2763 ///
2764 /// # Panics
2765 ///
2766 /// This function will panic if `rhs` is zero.
2767 ///
2768 /// # Examples
2769 ///
2770 /// ```
2771 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div_euclid(10), 10);")]
2772 /// ```
2773 #[stable(feature = "euclidean_division", since = "1.38.0")]
2774 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2775 #[must_use = "this returns the result of the operation, \
2776 without modifying the original"]
2777 #[inline(always)]
2778 #[track_caller]
2779 pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
2780 self / rhs
2781 }
2782
2783 /// Wrapping (modular) remainder. Computes `self % rhs`.
2784 ///
2785 /// Wrapped remainder calculation on unsigned types is just the regular
2786 /// remainder calculation. There's no way wrapping could ever happen.
2787 /// This function exists so that all operations are accounted for in the
2788 /// wrapping operations.
2789 ///
2790 /// # Panics
2791 ///
2792 /// This function will panic if `rhs` is zero.
2793 ///
2794 /// # Examples
2795 ///
2796 /// ```
2797 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem(10), 0);")]
2798 /// ```
2799 #[stable(feature = "num_wrapping", since = "1.2.0")]
2800 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2801 #[must_use = "this returns the result of the operation, \
2802 without modifying the original"]
2803 #[inline(always)]
2804 #[track_caller]
2805 pub const fn wrapping_rem(self, rhs: Self) -> Self {
2806 self % rhs
2807 }
2808
2809 /// Wrapping Euclidean modulo. Computes `self.rem_euclid(rhs)`.
2810 ///
2811 /// Wrapped modulo calculation on unsigned types is just the regular
2812 /// remainder calculation. There's no way wrapping could ever happen.
2813 /// This function exists so that all operations are accounted for in the
2814 /// wrapping operations. Since, for the positive integers, all common
2815 /// definitions of division are equal, this is exactly equal to
2816 /// `self.wrapping_rem(rhs)`.
2817 ///
2818 /// # Panics
2819 ///
2820 /// This function will panic if `rhs` is zero.
2821 ///
2822 /// # Examples
2823 ///
2824 /// ```
2825 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);")]
2826 /// ```
2827 #[stable(feature = "euclidean_division", since = "1.38.0")]
2828 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2829 #[must_use = "this returns the result of the operation, \
2830 without modifying the original"]
2831 #[inline(always)]
2832 #[track_caller]
2833 pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
2834 self % rhs
2835 }
2836
2837 /// Wrapping (modular) negation. Computes `-self`,
2838 /// wrapping around at the boundary of the type.
2839 ///
2840 /// Since unsigned types do not have negative equivalents
2841 /// all applications of this function will wrap (except for `-0`).
2842 /// For values smaller than the corresponding signed type's maximum
2843 /// the result is the same as casting the corresponding signed value.
2844 /// Any larger values are equivalent to `MAX + 1 - (val - MAX - 1)` where
2845 /// `MAX` is the corresponding signed type's maximum.
2846 ///
2847 /// # Examples
2848 ///
2849 /// ```
2850 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_neg(), 0);")]
2851 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_neg(), 1);")]
2852 #[doc = concat!("assert_eq!(13_", stringify!($SelfT), ".wrapping_neg(), (!13) + 1);")]
2853 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_neg(), !(42 - 1));")]
2854 /// ```
2855 #[stable(feature = "num_wrapping", since = "1.2.0")]
2856 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2857 #[must_use = "this returns the result of the operation, \
2858 without modifying the original"]
2859 #[inline(always)]
2860 pub const fn wrapping_neg(self) -> Self {
2861 (0 as $SelfT).wrapping_sub(self)
2862 }
2863
2864 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
2865 /// where `mask` removes any high-order bits of `rhs` that
2866 /// would cause the shift to exceed the bitwidth of the type.
2867 ///
2868 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2869 /// does *not* give the same result as doing the shift in infinite precision
2870 /// then truncating as needed. Instead, the behaviour of this method matches what shift instructions
2871 /// do on many processors, and is what the `<<` operator does when overflow
2872 /// checks are disabled, but numerically it's weird. Consider, instead,
2873 /// using [`Self::unbounded_shl`] which has nicer behaviour.
2874 ///
2875 /// Note that this is *not* the same as a rotate-left; the
2876 /// RHS of a wrapping shift-left is restricted to the range
2877 /// of the type, rather than the bits shifted out of the LHS
2878 /// being returned to the other end. The primitive integer
2879 /// types all implement a [`rotate_left`](Self::rotate_left) function,
2880 /// which may be what you want instead.
2881 ///
2882 /// # Examples
2883 ///
2884 /// ```
2885 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(7), 128);")]
2886 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(0), 0b101);")]
2887 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(1), 0b1010);")]
2888 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(2), 0b10100);")]
2889 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shl(2), ", stringify!($SelfT), "::MAX - 3);")]
2890 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(", stringify!($BITS), "), 42);")]
2891 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(1).wrapping_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2892 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(128), 1);")]
2893 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".wrapping_shl(1025), 10);")]
2894 /// ```
2895 #[stable(feature = "num_wrapping", since = "1.2.0")]
2896 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2897 #[must_use = "this returns the result of the operation, \
2898 without modifying the original"]
2899 #[inline(always)]
2900 pub const fn wrapping_shl(self, rhs: u32) -> Self {
2901 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2902 // out of bounds
2903 unsafe {
2904 self.unchecked_shl(rhs & (Self::BITS - 1))
2905 }
2906 }
2907
2908 /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
2909 /// where `mask` removes any high-order bits of `rhs` that
2910 /// would cause the shift to exceed the bitwidth of the type.
2911 ///
2912 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2913 /// does *not* give the same result as doing the shift in infinite precision
2914 /// then truncating as needed. Instead, the behaviour of this method matches what shift instructions
2915 /// do on many processors, and is what the `>>` operator does when overflow
2916 /// checks are disabled, but numerically it's weird. Consider, instead,
2917 /// using [`Self::unbounded_shr`] which has nicer behaviour.
2918 ///
2919 /// Note that this is *not* the same as a rotate-right; the
2920 /// RHS of a wrapping shift-right is restricted to the range
2921 /// of the type, rather than the bits shifted out of the LHS
2922 /// being returned to the other end. The primitive integer
2923 /// types all implement a [`rotate_right`](Self::rotate_right) function,
2924 /// which may be what you want instead.
2925 ///
2926 /// # Examples
2927 ///
2928 /// ```
2929 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(7), 1);")]
2930 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(0), 0b1010);")]
2931 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(1), 0b101);")]
2932 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(2), 0b10);")]
2933 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shr(1), ", stringify!($SignedT), "::MAX.cast_unsigned());")]
2934 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(", stringify!($BITS), "), 42);")]
2935 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(1).wrapping_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2936 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(128), 128);")]
2937 #[doc = concat!("assert_eq!(10_", stringify!($SelfT), ".wrapping_shr(1025), 5);")]
2938 /// ```
2939 #[stable(feature = "num_wrapping", since = "1.2.0")]
2940 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2941 #[must_use = "this returns the result of the operation, \
2942 without modifying the original"]
2943 #[inline(always)]
2944 pub const fn wrapping_shr(self, rhs: u32) -> Self {
2945 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2946 // out of bounds
2947 unsafe {
2948 self.unchecked_shr(rhs & (Self::BITS - 1))
2949 }
2950 }
2951
2952 /// Wrapping (modular) exponentiation. Computes `self.pow(exp)`,
2953 /// wrapping around at the boundary of the type.
2954 ///
2955 /// # Examples
2956 ///
2957 /// ```
2958 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(5), 243);")]
2959 /// assert_eq!(3u8.wrapping_pow(6), 217);
2960 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
2961 /// ```
2962 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2963 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2964 #[must_use = "this returns the result of the operation, \
2965 without modifying the original"]
2966 #[inline]
2967 pub const fn wrapping_pow(self, exp: u32) -> Self {
2968 let (a, _) = self.overflowing_pow(exp);
2969 a
2970 }
2971
2972 /// Calculates `self` + `rhs`.
2973 ///
2974 /// Returns a tuple of the addition along with a boolean indicating
2975 /// whether an arithmetic overflow would occur. If an overflow would
2976 /// have occurred then the wrapped value is returned.
2977 ///
2978 /// # Examples
2979 ///
2980 /// ```
2981 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_add(2), (7, false));")]
2982 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.overflowing_add(1), (0, true));")]
2983 /// ```
2984 #[stable(feature = "wrapping", since = "1.7.0")]
2985 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2986 #[must_use = "this returns the result of the operation, \
2987 without modifying the original"]
2988 #[inline(always)]
2989 pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
2990 let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
2991 (a as Self, b)
2992 }
2993
2994 /// Calculates `self` + `rhs` + `carry` and returns a tuple containing
2995 /// the sum and the output carry (in that order).
2996 ///
2997 /// Performs "ternary addition" of two integer operands and a carry-in
2998 /// bit, and returns an output integer and a carry-out bit. This allows
2999 /// chaining together multiple additions to create a wider addition, and
3000 /// can be useful for bignum addition.
3001 ///
3002 #[doc = concat!("This can be thought of as a ", stringify!($BITS), "-bit \"full adder\", in the electronics sense.")]
3003 ///
3004 /// If the input carry is false, this method is equivalent to
3005 /// [`overflowing_add`](Self::overflowing_add), and the output carry is
3006 /// equal to the overflow flag. Note that although carry and overflow
3007 /// flags are similar for unsigned integers, they are different for
3008 /// signed integers.
3009 ///
3010 /// # Examples
3011 ///
3012 /// ```
3013 #[doc = concat!("// 3 MAX (a = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3014 #[doc = concat!("// + 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3015 /// // ---------
3016 #[doc = concat!("// 9 6 (sum = 9 × 2^", stringify!($BITS), " + 6)")]
3017 ///
3018 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (3, ", stringify!($SelfT), "::MAX);")]
3019 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3020 /// let carry0 = false;
3021 ///
3022 /// let (sum0, carry1) = a0.carrying_add(b0, carry0);
3023 /// assert_eq!(carry1, true);
3024 /// let (sum1, carry2) = a1.carrying_add(b1, carry1);
3025 /// assert_eq!(carry2, false);
3026 ///
3027 /// assert_eq!((sum1, sum0), (9, 6));
3028 /// ```
3029 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3030 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3031 #[must_use = "this returns the result of the operation, \
3032 without modifying the original"]
3033 #[inline]
3034 pub const fn carrying_add(self, rhs: Self, carry: bool) -> (Self, bool) {
3035 // note: longer-term this should be done via an intrinsic, but this has been shown
3036 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3037 let (a, c1) = self.overflowing_add(rhs);
3038 let (b, c2) = a.overflowing_add(carry as $SelfT);
3039 // Ideally LLVM would know this is disjoint without us telling them,
3040 // but it doesn't <https://github.com/llvm/llvm-project/issues/118162>
3041 // SAFETY: Only one of `c1` and `c2` can be set.
3042 // For c1 to be set we need to have overflowed, but if we did then
3043 // `a` is at most `MAX-1`, which means that `c2` cannot possibly
3044 // overflow because it's adding at most `1` (since it came from `bool`)
3045 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3046 }
3047
3048 /// Calculates `self` + `rhs` with a signed `rhs`.
3049 ///
3050 /// Returns a tuple of the addition along with a boolean indicating
3051 /// whether an arithmetic overflow would occur. If an overflow would
3052 /// have occurred then the wrapped value is returned.
3053 ///
3054 /// # Examples
3055 ///
3056 /// ```
3057 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(2), (3, false));")]
3058 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(-2), (", stringify!($SelfT), "::MAX, true));")]
3059 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_add_signed(4), (1, true));")]
3060 /// ```
3061 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
3062 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
3063 #[must_use = "this returns the result of the operation, \
3064 without modifying the original"]
3065 #[inline]
3066 pub const fn overflowing_add_signed(self, rhs: $SignedT) -> (Self, bool) {
3067 let (res, overflowed) = self.overflowing_add(rhs as Self);
3068 (res, overflowed ^ (rhs < 0))
3069 }
3070
3071 /// Calculates `self` - `rhs`.
3072 ///
3073 /// Returns a tuple of the subtraction along with a boolean indicating
3074 /// whether an arithmetic overflow would occur. If an overflow would
3075 /// have occurred then the wrapped value is returned.
3076 ///
3077 /// # Examples
3078 ///
3079 /// ```
3080 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_sub(2), (3, false));")]
3081 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_sub(1), (", stringify!($SelfT), "::MAX, true));")]
3082 /// ```
3083 #[stable(feature = "wrapping", since = "1.7.0")]
3084 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3085 #[must_use = "this returns the result of the operation, \
3086 without modifying the original"]
3087 #[inline(always)]
3088 pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
3089 let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
3090 (a as Self, b)
3091 }
3092
3093 /// Calculates `self` − `rhs` − `borrow` and returns a tuple
3094 /// containing the difference and the output borrow.
3095 ///
3096 /// Performs "ternary subtraction" by subtracting both an integer
3097 /// operand and a borrow-in bit from `self`, and returns an output
3098 /// integer and a borrow-out bit. This allows chaining together multiple
3099 /// subtractions to create a wider subtraction, and can be useful for
3100 /// bignum subtraction.
3101 ///
3102 /// # Examples
3103 ///
3104 /// ```
3105 #[doc = concat!("// 9 6 (a = 9 × 2^", stringify!($BITS), " + 6)")]
3106 #[doc = concat!("// - 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3107 /// // ---------
3108 #[doc = concat!("// 3 MAX (diff = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3109 ///
3110 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (9, 6);")]
3111 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3112 /// let borrow0 = false;
3113 ///
3114 /// let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
3115 /// assert_eq!(borrow1, true);
3116 /// let (diff1, borrow2) = a1.borrowing_sub(b1, borrow1);
3117 /// assert_eq!(borrow2, false);
3118 ///
3119 #[doc = concat!("assert_eq!((diff1, diff0), (3, ", stringify!($SelfT), "::MAX));")]
3120 /// ```
3121 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3122 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3123 #[must_use = "this returns the result of the operation, \
3124 without modifying the original"]
3125 #[inline]
3126 pub const fn borrowing_sub(self, rhs: Self, borrow: bool) -> (Self, bool) {
3127 // note: longer-term this should be done via an intrinsic, but this has been shown
3128 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3129 let (a, c1) = self.overflowing_sub(rhs);
3130 let (b, c2) = a.overflowing_sub(borrow as $SelfT);
3131 // SAFETY: Only one of `c1` and `c2` can be set.
3132 // For c1 to be set we need to have underflowed, but if we did then
3133 // `a` is nonzero, which means that `c2` cannot possibly
3134 // underflow because it's subtracting at most `1` (since it came from `bool`)
3135 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3136 }
3137
3138 /// Calculates `self` - `rhs` with a signed `rhs`
3139 ///
3140 /// Returns a tuple of the subtraction along with a boolean indicating
3141 /// whether an arithmetic overflow would occur. If an overflow would
3142 /// have occurred then the wrapped value is returned.
3143 ///
3144 /// # Examples
3145 ///
3146 /// ```
3147 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(2), (", stringify!($SelfT), "::MAX, true));")]
3148 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(-2), (3, false));")]
3149 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_sub_signed(-4), (1, true));")]
3150 /// ```
3151 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3152 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3153 #[must_use = "this returns the result of the operation, \
3154 without modifying the original"]
3155 #[inline]
3156 pub const fn overflowing_sub_signed(self, rhs: $SignedT) -> (Self, bool) {
3157 let (res, overflow) = self.overflowing_sub(rhs as Self);
3158
3159 (res, overflow ^ (rhs < 0))
3160 }
3161
3162 /// Computes the absolute difference between `self` and `other`.
3163 ///
3164 /// # Examples
3165 ///
3166 /// ```
3167 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(80), 20", stringify!($SelfT), ");")]
3168 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(110), 10", stringify!($SelfT), ");")]
3169 /// ```
3170 #[stable(feature = "int_abs_diff", since = "1.60.0")]
3171 #[rustc_const_stable(feature = "int_abs_diff", since = "1.60.0")]
3172 #[must_use = "this returns the result of the operation, \
3173 without modifying the original"]
3174 #[inline]
3175 pub const fn abs_diff(self, other: Self) -> Self {
3176 if size_of::<Self>() == 1 {
3177 // Trick LLVM into generating the psadbw instruction when SSE2
3178 // is available and this function is autovectorized for u8's.
3179 (self as i32).wrapping_sub(other as i32).unsigned_abs() as Self
3180 } else {
3181 if self < other {
3182 other - self
3183 } else {
3184 self - other
3185 }
3186 }
3187 }
3188
3189 /// Calculates the multiplication of `self` and `rhs`.
3190 ///
3191 /// Returns a tuple of the multiplication along with a boolean
3192 /// indicating whether an arithmetic overflow would occur. If an
3193 /// overflow would have occurred then the wrapped value is returned.
3194 ///
3195 /// If you want the *value* of the overflow, rather than just *whether*
3196 /// an overflow occurred, see [`Self::carrying_mul`].
3197 ///
3198 /// # Examples
3199 ///
3200 /// Please note that this example is shared among integer types, which is why `u32` is used.
3201 ///
3202 /// ```
3203 /// assert_eq!(5u32.overflowing_mul(2), (10, false));
3204 /// assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));
3205 /// ```
3206 #[stable(feature = "wrapping", since = "1.7.0")]
3207 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3208 #[must_use = "this returns the result of the operation, \
3209 without modifying the original"]
3210 #[inline(always)]
3211 pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
3212 let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
3213 (a as Self, b)
3214 }
3215
3216 /// Calculates the "full multiplication" `self * rhs + carry`
3217 /// without the possibility to overflow.
3218 ///
3219 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3220 /// of the result as two separate values, in that order.
3221 ///
3222 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3223 /// additional amount of overflow. This allows for chaining together multiple
3224 /// multiplications to create "big integers" which represent larger values.
3225 ///
3226 /// If you also need to add a value, then use [`Self::carrying_mul_add`].
3227 ///
3228 /// # Examples
3229 ///
3230 /// Please note that this example is shared among integer types, which is why `u32` is used.
3231 ///
3232 /// ```
3233 /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
3234 /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
3235 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
3236 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
3237 #[doc = concat!("assert_eq!(",
3238 stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3239 "(0, ", stringify!($SelfT), "::MAX));"
3240 )]
3241 /// ```
3242 ///
3243 /// This is the core operation needed for scalar multiplication when
3244 /// implementing it for wider-than-native types.
3245 ///
3246 /// ```
3247 /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
3248 /// let mut carry = 0;
3249 /// for d in little_endian_digits.iter_mut() {
3250 /// (*d, carry) = d.carrying_mul(multiplicand, carry);
3251 /// }
3252 /// if carry != 0 {
3253 /// little_endian_digits.push(carry);
3254 /// }
3255 /// }
3256 ///
3257 /// let mut v = vec![10, 20];
3258 /// scalar_mul_eq(&mut v, 3);
3259 /// assert_eq!(v, [30, 60]);
3260 ///
3261 /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
3262 /// let mut v = vec![0x4321, 0x8765];
3263 /// scalar_mul_eq(&mut v, 0xFEED);
3264 /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
3265 /// ```
3266 ///
3267 /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
3268 /// except that it gives the value of the overflow instead of just whether one happened:
3269 ///
3270 /// ```
3271 /// # #![allow(unused_features)]
3272 /// #![feature(const_unsigned_bigint_helpers)]
3273 /// let r = u8::carrying_mul(7, 13, 0);
3274 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
3275 /// let r = u8::carrying_mul(13, 42, 0);
3276 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
3277 /// ```
3278 ///
3279 /// The value of the first field in the returned tuple matches what you'd get
3280 /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
3281 /// [`wrapping_add`](Self::wrapping_add) methods:
3282 ///
3283 /// ```
3284 /// # #![allow(unused_features)]
3285 /// #![feature(const_unsigned_bigint_helpers)]
3286 /// assert_eq!(
3287 /// 789_u16.carrying_mul(456, 123).0,
3288 /// 789_u16.wrapping_mul(456).wrapping_add(123),
3289 /// );
3290 /// ```
3291 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3292 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3293 #[must_use = "this returns the result of the operation, \
3294 without modifying the original"]
3295 #[inline]
3296 pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
3297 Self::carrying_mul_add(self, rhs, carry, 0)
3298 }
3299
3300 /// Calculates the "full multiplication" `self * rhs + carry + add`.
3301 ///
3302 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3303 /// of the result as two separate values, in that order.
3304 ///
3305 /// This cannot overflow, as the double-width result has exactly enough
3306 /// space for the largest possible result. This is equivalent to how, in
3307 /// decimal, 9 × 9 + 9 + 9 = 81 + 18 = 99 = 9×10⁰ + 9×10¹ = 10² - 1.
3308 ///
3309 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3310 /// additional amount of overflow. This allows for chaining together multiple
3311 /// multiplications to create "big integers" which represent larger values.
3312 ///
3313 /// If you don't need the `add` part, then you can use [`Self::carrying_mul`] instead.
3314 ///
3315 /// # Examples
3316 ///
3317 /// Please note that this example is shared between integer types,
3318 /// which explains why `u32` is used here.
3319 ///
3320 /// ```
3321 /// assert_eq!(5u32.carrying_mul_add(2, 0, 0), (10, 0));
3322 /// assert_eq!(5u32.carrying_mul_add(2, 10, 10), (30, 0));
3323 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 0, 0), (1410065408, 2));
3324 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 10, 10), (1410065428, 2));
3325 #[doc = concat!("assert_eq!(",
3326 stringify!($SelfT), "::MAX.carrying_mul_add(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3327 "(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX));"
3328 )]
3329 /// ```
3330 ///
3331 /// This is the core per-digit operation for "grade school" O(n²) multiplication.
3332 ///
3333 /// Please note that this example is shared between integer types,
3334 /// using `u8` for simplicity of the demonstration.
3335 ///
3336 /// ```
3337 /// fn quadratic_mul<const N: usize>(a: [u8; N], b: [u8; N]) -> [u8; N] {
3338 /// let mut out = [0; N];
3339 /// for j in 0..N {
3340 /// let mut carry = 0;
3341 /// for i in 0..(N - j) {
3342 /// (out[j + i], carry) = u8::carrying_mul_add(a[i], b[j], out[j + i], carry);
3343 /// }
3344 /// }
3345 /// out
3346 /// }
3347 ///
3348 /// // -1 * -1 == 1
3349 /// assert_eq!(quadratic_mul([0xFF; 3], [0xFF; 3]), [1, 0, 0]);
3350 ///
3351 /// assert_eq!(u32::wrapping_mul(0x9e3779b9, 0x7f4a7c15), 0xcffc982d);
3352 /// assert_eq!(
3353 /// quadratic_mul(u32::to_le_bytes(0x9e3779b9), u32::to_le_bytes(0x7f4a7c15)),
3354 /// u32::to_le_bytes(0xcffc982d)
3355 /// );
3356 /// ```
3357 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3358 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3359 #[must_use = "this returns the result of the operation, \
3360 without modifying the original"]
3361 #[inline]
3362 pub const fn carrying_mul_add(self, rhs: Self, carry: Self, add: Self) -> (Self, Self) {
3363 intrinsics::carrying_mul_add(self, rhs, carry, add)
3364 }
3365
3366 /// Calculates the divisor when `self` is divided by `rhs`.
3367 ///
3368 /// Returns a tuple of the divisor along with a boolean indicating
3369 /// whether an arithmetic overflow would occur. Note that for unsigned
3370 /// integers overflow never occurs, so the second value is always
3371 /// `false`.
3372 ///
3373 /// # Panics
3374 ///
3375 /// This function will panic if `rhs` is zero.
3376 ///
3377 /// # Examples
3378 ///
3379 /// ```
3380 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div(2), (2, false));")]
3381 /// ```
3382 #[inline(always)]
3383 #[stable(feature = "wrapping", since = "1.7.0")]
3384 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3385 #[must_use = "this returns the result of the operation, \
3386 without modifying the original"]
3387 #[track_caller]
3388 pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
3389 (self / rhs, false)
3390 }
3391
3392 /// Calculates the quotient of Euclidean division `self.div_euclid(rhs)`.
3393 ///
3394 /// Returns a tuple of the divisor along with a boolean indicating
3395 /// whether an arithmetic overflow would occur. Note that for unsigned
3396 /// integers overflow never occurs, so the second value is always
3397 /// `false`.
3398 /// Since, for the positive integers, all common
3399 /// definitions of division are equal, this
3400 /// is exactly equal to `self.overflowing_div(rhs)`.
3401 ///
3402 /// # Panics
3403 ///
3404 /// This function will panic if `rhs` is zero.
3405 ///
3406 /// # Examples
3407 ///
3408 /// ```
3409 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div_euclid(2), (2, false));")]
3410 /// ```
3411 #[inline(always)]
3412 #[stable(feature = "euclidean_division", since = "1.38.0")]
3413 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3414 #[must_use = "this returns the result of the operation, \
3415 without modifying the original"]
3416 #[track_caller]
3417 pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
3418 (self / rhs, false)
3419 }
3420
3421 /// Calculates the remainder when `self` is divided by `rhs`.
3422 ///
3423 /// Returns a tuple of the remainder after dividing along with a boolean
3424 /// indicating whether an arithmetic overflow would occur. Note that for
3425 /// unsigned integers overflow never occurs, so the second value is
3426 /// always `false`.
3427 ///
3428 /// # Panics
3429 ///
3430 /// This function will panic if `rhs` is zero.
3431 ///
3432 /// # Examples
3433 ///
3434 /// ```
3435 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem(2), (1, false));")]
3436 /// ```
3437 #[inline(always)]
3438 #[stable(feature = "wrapping", since = "1.7.0")]
3439 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3440 #[must_use = "this returns the result of the operation, \
3441 without modifying the original"]
3442 #[track_caller]
3443 pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
3444 (self % rhs, false)
3445 }
3446
3447 /// Calculates the remainder `self.rem_euclid(rhs)` as if by Euclidean division.
3448 ///
3449 /// Returns a tuple of the modulo after dividing along with a boolean
3450 /// indicating whether an arithmetic overflow would occur. Note that for
3451 /// unsigned integers overflow never occurs, so the second value is
3452 /// always `false`.
3453 /// Since, for the positive integers, all common
3454 /// definitions of division are equal, this operation
3455 /// is exactly equal to `self.overflowing_rem(rhs)`.
3456 ///
3457 /// # Panics
3458 ///
3459 /// This function will panic if `rhs` is zero.
3460 ///
3461 /// # Examples
3462 ///
3463 /// ```
3464 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem_euclid(2), (1, false));")]
3465 /// ```
3466 #[inline(always)]
3467 #[stable(feature = "euclidean_division", since = "1.38.0")]
3468 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3469 #[must_use = "this returns the result of the operation, \
3470 without modifying the original"]
3471 #[track_caller]
3472 pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
3473 (self % rhs, false)
3474 }
3475
3476 /// Negates self in an overflowing fashion.
3477 ///
3478 /// Returns `!self + 1` using wrapping operations to return the value
3479 /// that represents the negation of this unsigned value. Note that for
3480 /// positive unsigned values overflow always occurs, but negating 0 does
3481 /// not overflow.
3482 ///
3483 /// # Examples
3484 ///
3485 /// ```
3486 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_neg(), (0, false));")]
3487 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!($SelfT), ", true));")]
3488 /// ```
3489 #[inline(always)]
3490 #[stable(feature = "wrapping", since = "1.7.0")]
3491 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3492 #[must_use = "this returns the result of the operation, \
3493 without modifying the original"]
3494 pub const fn overflowing_neg(self) -> (Self, bool) {
3495 ((!self).wrapping_add(1), self != 0)
3496 }
3497
3498 /// Shifts self left by `rhs` bits.
3499 ///
3500 /// Returns a tuple of the shifted version of self along with a boolean
3501 /// indicating whether the shift value was larger than or equal to the
3502 /// number of bits. If the shift value is too large, then value is
3503 /// masked (N-1) where N is the number of bits, and this value is then
3504 /// used to perform the shift.
3505 ///
3506 /// # Examples
3507 ///
3508 /// ```
3509 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(4), (0x10, false));")]
3510 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(132), (0x10, true));")]
3511 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shl(", stringify!($BITS_MINUS_ONE), "), (0, false));")]
3512 /// ```
3513 #[stable(feature = "wrapping", since = "1.7.0")]
3514 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3515 #[must_use = "this returns the result of the operation, \
3516 without modifying the original"]
3517 #[inline(always)]
3518 pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
3519 (self.wrapping_shl(rhs), rhs >= Self::BITS)
3520 }
3521
3522 /// Shifts self right by `rhs` bits.
3523 ///
3524 /// Returns a tuple of the shifted version of self along with a boolean
3525 /// indicating whether the shift value was larger than or equal to the
3526 /// number of bits. If the shift value is too large, then value is
3527 /// masked (N-1) where N is the number of bits, and this value is then
3528 /// used to perform the shift.
3529 ///
3530 /// # Examples
3531 ///
3532 /// ```
3533 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(4), (0x1, false));")]
3534 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(132), (0x1, true));")]
3535 /// ```
3536 #[stable(feature = "wrapping", since = "1.7.0")]
3537 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3538 #[must_use = "this returns the result of the operation, \
3539 without modifying the original"]
3540 #[inline(always)]
3541 pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
3542 (self.wrapping_shr(rhs), rhs >= Self::BITS)
3543 }
3544
3545 /// Raises self to the power of `exp`, using exponentiation by squaring.
3546 ///
3547 /// Returns a tuple of the exponentiation along with a bool indicating
3548 /// whether an overflow happened.
3549 ///
3550 /// # Examples
3551 ///
3552 /// ```
3553 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(5), (243, false));")]
3554 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
3555 /// assert_eq!(3u8.overflowing_pow(6), (217, true));
3556 /// ```
3557 #[stable(feature = "no_panic_pow", since = "1.34.0")]
3558 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3559 #[must_use = "this returns the result of the operation, \
3560 without modifying the original"]
3561 #[inline]
3562 pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
3563 let mut base = self;
3564 let mut acc: Self = 1;
3565 let mut overflow = false;
3566 let mut tmp_overflow;
3567
3568 if intrinsics::is_val_statically_known(base) && base.is_power_of_two() {
3569 // change of base:
3570 // if base == 2 ** k, then
3571 // (2 ** k) ** n
3572 // == 2 ** (k * n)
3573 // == 1 << (k * n)
3574 let k = base.ilog2();
3575 let Some(shift) = k.checked_mul(exp) else {
3576 return (0, true)
3577 };
3578 return ((1 as Self).unbounded_shl(shift), shift >= Self::BITS)
3579 }
3580
3581 if exp == 0 {
3582 return (1, false);
3583 }
3584
3585 if intrinsics::is_val_statically_known(exp) {
3586 while exp > 1 {
3587 if (exp & 1) == 1 {
3588 (acc, tmp_overflow) = acc.overflowing_mul(base);
3589 overflow |= tmp_overflow;
3590 }
3591 exp /= 2;
3592 (base, tmp_overflow) = base.overflowing_mul(base);
3593 overflow |= tmp_overflow;
3594 }
3595
3596 // since exp!=0, finally the exp must be 1.
3597 // Deal with the final bit of the exponent separately, since
3598 // squaring the base afterwards is not necessary and may cause a
3599 // needless overflow.
3600 (acc, tmp_overflow) = acc.overflowing_mul(base);
3601 overflow |= tmp_overflow;
3602 return (acc, overflow);
3603 }
3604
3605 loop {
3606 if (exp & 1) == 1 {
3607 (acc, tmp_overflow) = acc.overflowing_mul(base);
3608 overflow |= tmp_overflow;
3609 // since exp!=0, finally the exp must be 1.
3610 if exp == 1 {
3611 return (acc, overflow);
3612 }
3613 }
3614 exp /= 2;
3615 (base, tmp_overflow) = base.overflowing_mul(base);
3616 overflow |= tmp_overflow;
3617 }
3618 }
3619
3620 /// Raises self to the power of `exp`, using exponentiation by squaring.
3621 ///
3622 /// # Examples
3623 ///
3624 /// ```
3625 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".pow(5), 32);")]
3626 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(0), 1);")]
3627 /// ```
3628 #[stable(feature = "rust1", since = "1.0.0")]
3629 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3630 #[must_use = "this returns the result of the operation, \
3631 without modifying the original"]
3632 #[inline]
3633 #[rustc_inherit_overflow_checks]
3634 pub const fn pow(self, exp: u32) -> Self {
3635 if intrinsics::overflow_checks() {
3636 self.strict_pow(exp)
3637 } else {
3638 self.wrapping_pow(exp)
3639 }
3640 }
3641
3642 /// Returns the square root of the number, rounded down.
3643 ///
3644 /// # Examples
3645 ///
3646 /// ```
3647 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".isqrt(), 3);")]
3648 /// ```
3649 #[stable(feature = "isqrt", since = "1.84.0")]
3650 #[rustc_const_stable(feature = "isqrt", since = "1.84.0")]
3651 #[must_use = "this returns the result of the operation, \
3652 without modifying the original"]
3653 #[inline]
3654 pub const fn isqrt(self) -> Self {
3655 let result = imp::int_sqrt::$ActualT(self as $ActualT) as Self;
3656
3657 // Inform the optimizer what the range of outputs is. If testing
3658 // `core` crashes with no panic message and a `num::int_sqrt::u*`
3659 // test failed, it's because your edits caused these assertions or
3660 // the assertions in `fn isqrt` of `nonzero.rs` to become false.
3661 //
3662 // SAFETY: Integer square root is a monotonically nondecreasing
3663 // function, which means that increasing the input will never
3664 // cause the output to decrease. Thus, since the input for unsigned
3665 // integers is bounded by `[0, <$ActualT>::MAX]`, sqrt(n) will be
3666 // bounded by `[sqrt(0), sqrt(<$ActualT>::MAX)]` and bounding the
3667 // input by `[1, <$ActualT>::MAX]` bounds sqrt(n) by
3668 // `[sqrt(1), sqrt(<$ActualT>::MAX)]`.
3669 unsafe {
3670 const MAX_RESULT: $SelfT = imp::int_sqrt::$ActualT(<$ActualT>::MAX) as $SelfT;
3671 crate::hint::assert_unchecked(result <= MAX_RESULT)
3672 }
3673
3674 if self >= 1 {
3675 // SAFETY: The above statements about monotonicity also apply here.
3676 // Since the input in this branch is bounded by `[1, <$ActualT>::MAX]`,
3677 // sqrt(n) is bounded by `[sqrt(1), sqrt(<$ActualT>::MAX)]`, and
3678 // `sqrt(1) == 1`.
3679 unsafe { crate::hint::assert_unchecked(result >= 1) }
3680 }
3681
3682 // SAFETY: the isqrt implementation returns the square root and rounds down,
3683 // meaning `result * result <= self`. This implies `result <= self`.
3684 // The compiler needs both to optimize for both.
3685 // `result * result <= self` implies the multiplication will not overflow.
3686 unsafe {
3687 crate::hint::assert_unchecked(result.unchecked_mul(result) <= self);
3688 crate::hint::assert_unchecked(result <= self);
3689 }
3690
3691 result
3692 }
3693
3694 /// Performs Euclidean division.
3695 ///
3696 /// Since, for the positive integers, all common
3697 /// definitions of division are equal, this
3698 /// is exactly equal to `self / rhs`.
3699 ///
3700 /// # Panics
3701 ///
3702 /// This function will panic if `rhs` is zero.
3703 ///
3704 /// # Examples
3705 ///
3706 /// ```
3707 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".div_euclid(4), 1); // or any other integer type")]
3708 /// ```
3709 #[stable(feature = "euclidean_division", since = "1.38.0")]
3710 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3711 #[must_use = "this returns the result of the operation, \
3712 without modifying the original"]
3713 #[inline(always)]
3714 #[track_caller]
3715 pub const fn div_euclid(self, rhs: Self) -> Self {
3716 self / rhs
3717 }
3718
3719
3720 /// Calculates the least remainder of `self` when divided by
3721 /// `rhs`.
3722 ///
3723 /// Since, for the positive integers, all common
3724 /// definitions of division are equal, this
3725 /// is exactly equal to `self % rhs`.
3726 ///
3727 /// # Panics
3728 ///
3729 /// This function will panic if `rhs` is zero.
3730 ///
3731 /// # Examples
3732 ///
3733 /// ```
3734 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer type")]
3735 /// ```
3736 #[doc(alias = "modulo", alias = "mod")]
3737 #[stable(feature = "euclidean_division", since = "1.38.0")]
3738 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3739 #[must_use = "this returns the result of the operation, \
3740 without modifying the original"]
3741 #[inline(always)]
3742 #[track_caller]
3743 pub const fn rem_euclid(self, rhs: Self) -> Self {
3744 self % rhs
3745 }
3746
3747 /// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
3748 ///
3749 /// This is the same as performing `self / rhs` for all unsigned integers.
3750 ///
3751 /// # Panics
3752 ///
3753 /// This function will panic if `rhs` is zero.
3754 ///
3755 /// # Examples
3756 ///
3757 /// ```
3758 /// #![feature(int_roundings)]
3759 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_floor(4), 1);")]
3760 /// ```
3761 #[unstable(feature = "int_roundings", issue = "88581")]
3762 #[must_use = "this returns the result of the operation, \
3763 without modifying the original"]
3764 #[inline(always)]
3765 #[track_caller]
3766 pub const fn div_floor(self, rhs: Self) -> Self {
3767 self / rhs
3768 }
3769
3770 /// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
3771 ///
3772 /// # Panics
3773 ///
3774 /// This function will panic if `rhs` is zero.
3775 ///
3776 /// # Examples
3777 ///
3778 /// ```
3779 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_ceil(4), 2);")]
3780 /// ```
3781 #[stable(feature = "int_roundings1", since = "1.73.0")]
3782 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3783 #[must_use = "this returns the result of the operation, \
3784 without modifying the original"]
3785 #[inline]
3786 #[track_caller]
3787 pub const fn div_ceil(self, rhs: Self) -> Self {
3788 let d = self / rhs;
3789 let r = self % rhs;
3790 if r > 0 {
3791 d + 1
3792 } else {
3793 d
3794 }
3795 }
3796
3797 /// Calculates the smallest value greater than or equal to `self` that
3798 /// is a multiple of `rhs`.
3799 ///
3800 /// # Panics
3801 ///
3802 /// This function will panic if `rhs` is zero.
3803 ///
3804 /// ## Overflow behavior
3805 ///
3806 /// On overflow, this function will panic if overflow checks are enabled (default in debug
3807 /// mode) and wrap if overflow checks are disabled (default in release mode).
3808 ///
3809 /// # Examples
3810 ///
3811 /// ```
3812 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(8), 16);")]
3813 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(8), 24);")]
3814 /// ```
3815 #[stable(feature = "int_roundings1", since = "1.73.0")]
3816 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3817 #[must_use = "this returns the result of the operation, \
3818 without modifying the original"]
3819 #[inline]
3820 #[rustc_inherit_overflow_checks]
3821 pub const fn next_multiple_of(self, rhs: Self) -> Self {
3822 match self % rhs {
3823 0 => self,
3824 r => self + (rhs - r)
3825 }
3826 }
3827
3828 /// Calculates the smallest value greater than or equal to `self` that
3829 /// is a multiple of `rhs`. Returns `None` if `rhs` is zero or the
3830 /// operation would result in overflow.
3831 ///
3832 /// # Examples
3833 ///
3834 /// ```
3835 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(16));")]
3836 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(24));")]
3837 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_next_multiple_of(0), None);")]
3838 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_multiple_of(2), None);")]
3839 /// ```
3840 #[stable(feature = "int_roundings1", since = "1.73.0")]
3841 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3842 #[must_use = "this returns the result of the operation, \
3843 without modifying the original"]
3844 #[inline]
3845 pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
3846 match try_opt!(self.checked_rem(rhs)) {
3847 0 => Some(self),
3848 // rhs - r cannot overflow because r is smaller than rhs
3849 r => self.checked_add(rhs - r)
3850 }
3851 }
3852
3853 /// Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
3854 ///
3855 /// This function is equivalent to `self % rhs == 0`, except that it will not panic
3856 /// for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`,
3857 /// `n.is_multiple_of(0) == false`.
3858 ///
3859 /// # Examples
3860 ///
3861 /// ```
3862 #[doc = concat!("assert!(6_", stringify!($SelfT), ".is_multiple_of(2));")]
3863 #[doc = concat!("assert!(!5_", stringify!($SelfT), ".is_multiple_of(2));")]
3864 ///
3865 #[doc = concat!("assert!(0_", stringify!($SelfT), ".is_multiple_of(0));")]
3866 #[doc = concat!("assert!(!6_", stringify!($SelfT), ".is_multiple_of(0));")]
3867 /// ```
3868 #[stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3869 #[rustc_const_stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3870 #[must_use]
3871 #[inline]
3872 pub const fn is_multiple_of(self, rhs: Self) -> bool {
3873 match rhs {
3874 0 => self == 0,
3875 _ => self % rhs == 0,
3876 }
3877 }
3878
3879 /// Returns `true` if and only if `self == 2^k` for some unsigned integer `k`.
3880 ///
3881 /// # Examples
3882 ///
3883 /// ```
3884 #[doc = concat!("assert!(16", stringify!($SelfT), ".is_power_of_two());")]
3885 #[doc = concat!("assert!(!10", stringify!($SelfT), ".is_power_of_two());")]
3886 /// ```
3887 #[must_use]
3888 #[stable(feature = "rust1", since = "1.0.0")]
3889 #[rustc_const_stable(feature = "const_is_power_of_two", since = "1.32.0")]
3890 #[inline(always)]
3891 pub const fn is_power_of_two(self) -> bool {
3892 self.count_ones() == 1
3893 }
3894
3895 // Returns one less than next power of two.
3896 // (For 8u8 next power of two is 8u8 and for 6u8 it is 8u8)
3897 //
3898 // 8u8.one_less_than_next_power_of_two() == 7
3899 // 6u8.one_less_than_next_power_of_two() == 7
3900 //
3901 // This method cannot overflow, as in the `next_power_of_two`
3902 // overflow cases it instead ends up returning the maximum value
3903 // of the type, and can return 0 for 0.
3904 #[inline]
3905 const fn one_less_than_next_power_of_two(self) -> Self {
3906 if self <= 1 { return 0; }
3907
3908 let p = self - 1;
3909 // SAFETY: Because `p > 0`, it cannot consist entirely of leading zeros.
3910 // That means the shift is always in-bounds, and some processors
3911 // (such as intel pre-haswell) have more efficient ctlz
3912 // intrinsics when the argument is non-zero.
3913 let z = unsafe { intrinsics::ctlz_nonzero(p) };
3914 <$SelfT>::MAX >> z
3915 }
3916
3917 /// Returns the smallest power of two greater than or equal to `self`.
3918 ///
3919 /// When return value overflows (i.e., `self > (1 << (N-1))` for type
3920 /// `uN`), it panics in debug mode and the return value is wrapped to 0 in
3921 /// release mode (the only situation in which this method can return 0).
3922 ///
3923 /// # Examples
3924 ///
3925 /// ```
3926 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".next_power_of_two(), 2);")]
3927 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".next_power_of_two(), 4);")]
3928 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".next_power_of_two(), 1);")]
3929 /// ```
3930 #[stable(feature = "rust1", since = "1.0.0")]
3931 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3932 #[must_use = "this returns the result of the operation, \
3933 without modifying the original"]
3934 #[inline]
3935 #[rustc_inherit_overflow_checks]
3936 pub const fn next_power_of_two(self) -> Self {
3937 self.one_less_than_next_power_of_two() + 1
3938 }
3939
3940 /// Returns the smallest power of two greater than or equal to `self`. If
3941 /// the next power of two is greater than the type's maximum value,
3942 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
3943 ///
3944 /// # Examples
3945 ///
3946 /// ```
3947 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_next_power_of_two(), Some(2));")]
3948 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".checked_next_power_of_two(), Some(4));")]
3949 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_power_of_two(), None);")]
3950 /// ```
3951 #[inline]
3952 #[stable(feature = "rust1", since = "1.0.0")]
3953 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3954 #[must_use = "this returns the result of the operation, \
3955 without modifying the original"]
3956 pub const fn checked_next_power_of_two(self) -> Option<Self> {
3957 self.one_less_than_next_power_of_two().checked_add(1)
3958 }
3959
3960 /// Returns the smallest power of two greater than or equal to `n`. If
3961 /// the next power of two is greater than the type's maximum value,
3962 /// the return value is wrapped to `0`.
3963 ///
3964 /// # Examples
3965 ///
3966 /// ```
3967 /// #![feature(wrapping_next_power_of_two)]
3968 ///
3969 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".wrapping_next_power_of_two(), 2);")]
3970 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_next_power_of_two(), 4);")]
3971 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_next_power_of_two(), 0);")]
3972 /// ```
3973 #[inline]
3974 #[unstable(feature = "wrapping_next_power_of_two", issue = "32463",
3975 reason = "needs decision on wrapping behavior")]
3976 #[must_use = "this returns the result of the operation, \
3977 without modifying the original"]
3978 pub const fn wrapping_next_power_of_two(self) -> Self {
3979 self.one_less_than_next_power_of_two().wrapping_add(1)
3980 }
3981
3982 /// Returns the memory representation of this integer as a byte array in
3983 /// big-endian (network) byte order.
3984 ///
3985 #[doc = $to_xe_bytes_doc]
3986 ///
3987 /// # Examples
3988 ///
3989 /// ```
3990 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();")]
3991 #[doc = concat!("assert_eq!(bytes, ", $be_bytes, ");")]
3992 /// ```
3993 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
3994 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
3995 #[must_use = "this returns the result of the operation, \
3996 without modifying the original"]
3997 #[inline]
3998 pub const fn to_be_bytes(self) -> [u8; size_of::<Self>()] {
3999 self.to_be().to_ne_bytes()
4000 }
4001
4002 /// Returns the memory representation of this integer as a byte array in
4003 /// little-endian byte order.
4004 ///
4005 #[doc = $to_xe_bytes_doc]
4006 ///
4007 /// # Examples
4008 ///
4009 /// ```
4010 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();")]
4011 #[doc = concat!("assert_eq!(bytes, ", $le_bytes, ");")]
4012 /// ```
4013 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4014 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4015 #[must_use = "this returns the result of the operation, \
4016 without modifying the original"]
4017 #[inline]
4018 pub const fn to_le_bytes(self) -> [u8; size_of::<Self>()] {
4019 self.to_le().to_ne_bytes()
4020 }
4021
4022 /// Returns the memory representation of this integer as a byte array in
4023 /// native byte order.
4024 ///
4025 /// As the target platform's native endianness is used, portable code
4026 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate,
4027 /// instead.
4028 ///
4029 #[doc = $to_xe_bytes_doc]
4030 ///
4031 /// [`to_be_bytes`]: Self::to_be_bytes
4032 /// [`to_le_bytes`]: Self::to_le_bytes
4033 ///
4034 /// # Examples
4035 ///
4036 /// ```
4037 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_ne_bytes();")]
4038 /// assert_eq!(
4039 /// bytes,
4040 /// if cfg!(target_endian = "big") {
4041 #[doc = concat!(" ", $be_bytes)]
4042 /// } else {
4043 #[doc = concat!(" ", $le_bytes)]
4044 /// }
4045 /// );
4046 /// ```
4047 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4048 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4049 #[must_use = "this returns the result of the operation, \
4050 without modifying the original"]
4051 #[allow(unnecessary_transmutes)]
4052 // SAFETY: const sound because integers are plain old datatypes so we can always
4053 // transmute them to arrays of bytes
4054 #[inline]
4055 pub const fn to_ne_bytes(self) -> [u8; size_of::<Self>()] {
4056 // SAFETY: integers are plain old datatypes so we can always transmute them to
4057 // arrays of bytes
4058 unsafe { mem::transmute(self) }
4059 }
4060
4061 /// Creates a native endian integer value from its representation
4062 /// as a byte array in big endian.
4063 ///
4064 #[doc = $from_xe_bytes_doc]
4065 ///
4066 /// # Examples
4067 ///
4068 /// ```
4069 #[doc = concat!("let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");")]
4070 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4071 /// ```
4072 ///
4073 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4074 ///
4075 /// ```
4076 #[doc = concat!("fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4077 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4078 /// *input = rest;
4079 #[doc = concat!(" ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())")]
4080 /// }
4081 /// ```
4082 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4083 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4084 #[must_use]
4085 #[inline]
4086 pub const fn from_be_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4087 Self::from_be(Self::from_ne_bytes(bytes))
4088 }
4089
4090 /// Creates a native endian integer value from its representation
4091 /// as a byte array in little endian.
4092 ///
4093 #[doc = $from_xe_bytes_doc]
4094 ///
4095 /// # Examples
4096 ///
4097 /// ```
4098 #[doc = concat!("let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");")]
4099 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4100 /// ```
4101 ///
4102 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4103 ///
4104 /// ```
4105 #[doc = concat!("fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4106 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4107 /// *input = rest;
4108 #[doc = concat!(" ", stringify!($SelfT), "::from_le_bytes(int_bytes.try_into().unwrap())")]
4109 /// }
4110 /// ```
4111 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4112 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4113 #[must_use]
4114 #[inline]
4115 pub const fn from_le_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4116 Self::from_le(Self::from_ne_bytes(bytes))
4117 }
4118
4119 /// Creates a native endian integer value from its memory representation
4120 /// as a byte array in native endianness.
4121 ///
4122 /// As the target platform's native endianness is used, portable code
4123 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
4124 /// appropriate instead.
4125 ///
4126 /// [`from_be_bytes`]: Self::from_be_bytes
4127 /// [`from_le_bytes`]: Self::from_le_bytes
4128 ///
4129 #[doc = $from_xe_bytes_doc]
4130 ///
4131 /// # Examples
4132 ///
4133 /// ```
4134 #[doc = concat!("let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"big\") {")]
4135 #[doc = concat!(" ", $be_bytes, "")]
4136 /// } else {
4137 #[doc = concat!(" ", $le_bytes, "")]
4138 /// });
4139 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4140 /// ```
4141 ///
4142 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4143 ///
4144 /// ```
4145 #[doc = concat!("fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4146 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4147 /// *input = rest;
4148 #[doc = concat!(" ", stringify!($SelfT), "::from_ne_bytes(int_bytes.try_into().unwrap())")]
4149 /// }
4150 /// ```
4151 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4152 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4153 #[allow(unnecessary_transmutes)]
4154 #[must_use]
4155 // SAFETY: const sound because integers are plain old datatypes so we can always
4156 // transmute to them
4157 #[inline]
4158 pub const fn from_ne_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4159 // SAFETY: integers are plain old datatypes so we can always transmute to them
4160 unsafe { mem::transmute(bytes) }
4161 }
4162
4163 /// New code should prefer to use
4164 #[doc = concat!("[`", stringify!($SelfT), "::MIN", "`] instead.")]
4165 ///
4166 /// Returns the smallest value that can be represented by this integer type.
4167 #[stable(feature = "rust1", since = "1.0.0")]
4168 #[rustc_promotable]
4169 #[inline(always)]
4170 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4171 #[deprecated(since = "CURRENT_RUSTC_VERSION", note = "replaced by the `MIN` associated constant on this type")]
4172 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_min_value")]
4173 pub const fn min_value() -> Self { Self::MIN }
4174
4175 /// New code should prefer to use
4176 #[doc = concat!("[`", stringify!($SelfT), "::MAX", "`] instead.")]
4177 ///
4178 /// Returns the largest value that can be represented by this integer type.
4179 #[stable(feature = "rust1", since = "1.0.0")]
4180 #[rustc_promotable]
4181 #[inline(always)]
4182 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4183 #[deprecated(since = "CURRENT_RUSTC_VERSION", note = "replaced by the `MAX` associated constant on this type")]
4184 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_max_value")]
4185 pub const fn max_value() -> Self { Self::MAX }
4186
4187 /// Truncate an integer to an integer of the same size or smaller, preserving the least
4188 /// significant bits.
4189 ///
4190 /// # Examples
4191 ///
4192 /// ```
4193 /// #![feature(integer_widen_truncate)]
4194 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".truncate());")]
4195 /// assert_eq!(120u8, 376u32.truncate());
4196 /// ```
4197 #[must_use = "this returns the truncated value and does not modify the original"]
4198 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4199 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4200 #[inline]
4201 pub const fn truncate<Target>(self) -> Target
4202 where Self: [const] traits::TruncateTarget<Target>
4203 {
4204 traits::TruncateTarget::internal_truncate(self)
4205 }
4206
4207 /// Truncate an integer to an integer of the same size or smaller, saturating at numeric bounds
4208 /// instead of truncating.
4209 ///
4210 /// # Examples
4211 ///
4212 /// ```
4213 /// #![feature(integer_widen_truncate)]
4214 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".saturating_truncate());")]
4215 /// assert_eq!(255u8, 376u32.saturating_truncate());
4216 /// ```
4217 #[must_use = "this returns the truncated value and does not modify the original"]
4218 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4219 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4220 #[inline]
4221 pub const fn saturating_truncate<Target>(self) -> Target
4222 where Self: [const] traits::TruncateTarget<Target>
4223 {
4224 traits::TruncateTarget::internal_saturating_truncate(self)
4225 }
4226
4227 /// Truncate an integer to an integer of the same size or smaller, returning `None` if the value
4228 /// is outside the bounds of the smaller type.
4229 ///
4230 /// # Examples
4231 ///
4232 /// ```
4233 /// #![feature(integer_widen_truncate)]
4234 #[doc = concat!("assert_eq!(Some(120u8), 120", stringify!($SelfT), ".checked_truncate());")]
4235 /// assert_eq!(None, 376u32.checked_truncate::<u8>());
4236 /// ```
4237 #[must_use = "this returns the truncated value and does not modify the original"]
4238 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4239 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4240 #[inline]
4241 pub const fn checked_truncate<Target>(self) -> Option<Target>
4242 where Self: [const] traits::TruncateTarget<Target>
4243 {
4244 traits::TruncateTarget::internal_checked_truncate(self)
4245 }
4246
4247 /// Widen to an integer of the same size or larger, preserving its value.
4248 ///
4249 /// # Examples
4250 ///
4251 /// ```
4252 /// #![feature(integer_widen_truncate)]
4253 #[doc = concat!("assert_eq!(120u128, 120u8.widen());")]
4254 /// ```
4255 #[must_use = "this returns the widened value and does not modify the original"]
4256 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4257 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4258 #[inline]
4259 pub const fn widen<Target>(self) -> Target
4260 where Self: [const] traits::WidenTarget<Target>
4261 {
4262 traits::WidenTarget::internal_widen(self)
4263 }
4264
4265 /// Converts `self` to the target integer type, saturating at the numeric
4266 /// bounds instead of overflowing.
4267 ///
4268 /// # Examples
4269 ///
4270 /// ```
4271 /// #![feature(integer_casts)]
4272 #[doc = concat!("assert_eq!(255u8, ", stringify!($SelfT), "::MAX.saturating_cast());")]
4273 #[doc = concat!("assert_eq!(127i8, ", stringify!($SelfT), "::MAX.saturating_cast());")]
4274 #[doc = concat!("assert_eq!(42i8, 42", stringify!($SelfT), ".saturating_cast());")]
4275 /// ```
4276 #[must_use = "this returns the cast result and does not modify the original"]
4277 #[unstable(feature = "integer_casts", issue = "157388")]
4278 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4279 #[inline(always)]
4280 pub const fn saturating_cast<T: [const] BoundedCastFromInt<Self>>(self) -> T {
4281 T::saturating_cast_from(self)
4282 }
4283
4284 /// Converts `self` to the target integer type, wrapping around at the
4285 /// boundary of the target type.
4286 ///
4287 /// # Examples
4288 ///
4289 /// ```
4290 /// #![feature(integer_casts)]
4291 #[doc = concat!("assert_eq!(255u8, ", stringify!($SelfT), "::MAX.wrapping_cast());")]
4292 #[doc = concat!("assert_eq!(42i8, 42", stringify!($SelfT), ".wrapping_cast());")]
4293 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX as i8, ", stringify!($SelfT), "::MAX.wrapping_cast());")]
4294 /// ```
4295 #[must_use = "this returns the cast result and does not modify the original"]
4296 #[unstable(feature = "integer_casts", issue = "157388")]
4297 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4298 #[inline(always)]
4299 pub const fn wrapping_cast<T: [const] BoundedCastFromInt<Self>>(self) -> T {
4300 T::wrapping_cast_from(self)
4301 }
4302
4303 /// Converts `self` to the target integer type, returning `None` if the value
4304 /// is not representable by the target type.
4305 ///
4306 /// # Examples
4307 ///
4308 /// ```
4309 /// #![feature(integer_casts)]
4310 #[doc = concat!("assert_eq!(Some(42u8), 42", stringify!($SelfT), ".checked_cast());")]
4311 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_cast::<i8>(), None);")]
4312 /// ```
4313 #[must_use = "this returns the cast result and does not modify the original"]
4314 #[unstable(feature = "integer_casts", issue = "157388")]
4315 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4316 #[inline(always)]
4317 pub const fn checked_cast<T: [const] CheckedCastFromInt<Self>>(self) -> Option<T> {
4318 T::checked_cast_from(self)
4319 }
4320
4321 /// Converts `self` to the target integer type, panicking if the value
4322 /// is not representable by the target type.
4323 ///
4324 /// # Panics
4325 ///
4326 /// This function will panic if the value is not representable by the target type.
4327 ///
4328 /// # Examples
4329 ///
4330 /// ```
4331 /// #![feature(integer_casts)]
4332 #[doc = concat!("assert_eq!(42u8, 42", stringify!($SelfT), ".strict_cast());")]
4333 /// ```
4334 ///
4335 /// The following will panic:
4336 ///
4337 /// ```should_panic
4338 /// #![feature(integer_casts)]
4339 #[doc = concat!("let _ = 128", stringify!($SelfT), ".strict_cast::<i8>();")]
4340 /// ```
4341 #[must_use = "this returns the cast result and does not modify the original"]
4342 #[unstable(feature = "integer_casts", issue = "157388")]
4343 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4344 #[inline(always)]
4345 #[track_caller]
4346 pub const fn strict_cast<T: [const] CheckedCastFromInt<Self>>(self) -> T {
4347 T::strict_cast_from(self)
4348 }
4349
4350 /// Converts `self` to the target integer type, assuming the value is
4351 /// representable by the target type.
4352 ///
4353 /// # Safety
4354 ///
4355 /// This results in undefined behavior if the integer value of `self` is bigger than `T::MAX`,
4356 /// or smaller than `T::MIN`, where `T` is the target type.
4357 #[must_use = "this returns the cast result and does not modify the original"]
4358 #[unstable(feature = "integer_casts", issue = "157388")]
4359 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4360 #[inline(always)]
4361 pub const unsafe fn unchecked_cast<T: [const] CheckedCastFromInt<Self>>(self) -> T {
4362 assert_unsafe_precondition!(
4363 check_language_ub,
4364 concat!(stringify!($SelfT), "::unchecked_cast must fit in the target type"),
4365 (
4366 // Check has to be performed up-front because it depends on generic T.
4367 in_bounds: bool = {
4368 let cast_val = self.checked_cast::<T>();
4369 let ret = cast_val.is_some();
4370 core::mem::forget(cast_val); // We don't have const Drop, but we know it's an int.
4371 ret
4372 },
4373 ) => in_bounds,
4374 );
4375
4376 // SAFETY: this is guaranteed to be safe by the caller.
4377 unsafe { T::unchecked_cast_from(self) }
4378 }
4379 }
4380}