rand/distributions/
integer.rs

1// Copyright 2018 Developers of the Rand project.
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9//! The implementations of the `Standard` distribution for integer types.
10
11use crate::distributions::{Distribution, Standard};
12use crate::Rng;
13#[cfg(all(target_arch = "x86", feature = "simd_support"))]
14use core::arch::x86::{__m128i, __m256i};
15#[cfg(all(target_arch = "x86_64", feature = "simd_support"))]
16use core::arch::x86_64::{__m128i, __m256i};
17use core::num::{NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize,
18    NonZeroU128};
19#[cfg(feature = "simd_support")] use packed_simd::*;
20
21impl Distribution<u8> for Standard {
22    #[inline]
23    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> u8 {
24        rng.next_u32() as u8
25    }
26}
27
28impl Distribution<u16> for Standard {
29    #[inline]
30    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> u16 {
31        rng.next_u32() as u16
32    }
33}
34
35impl Distribution<u32> for Standard {
36    #[inline]
37    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> u32 {
38        rng.next_u32()
39    }
40}
41
42impl Distribution<u64> for Standard {
43    #[inline]
44    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> u64 {
45        rng.next_u64()
46    }
47}
48
49impl Distribution<u128> for Standard {
50    #[inline]
51    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> u128 {
52        // Use LE; we explicitly generate one value before the next.
53        let x = u128::from(rng.next_u64());
54        let y = u128::from(rng.next_u64());
55        (y << 64) | x
56    }
57}
58
59impl Distribution<usize> for Standard {
60    #[inline]
61    #[cfg(any(target_pointer_width = "32", target_pointer_width = "16"))]
62    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> usize {
63        rng.next_u32() as usize
64    }
65
66    #[inline]
67    #[cfg(target_pointer_width = "64")]
68    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> usize {
69        rng.next_u64() as usize
70    }
71}
72
73macro_rules! impl_int_from_uint {
74    ($ty:ty, $uty:ty) => {
75        impl Distribution<$ty> for Standard {
76            #[inline]
77            fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> $ty {
78                rng.gen::<$uty>() as $ty
79            }
80        }
81    };
82}
83
84impl_int_from_uint! { i8, u8 }
85impl_int_from_uint! { i16, u16 }
86impl_int_from_uint! { i32, u32 }
87impl_int_from_uint! { i64, u64 }
88impl_int_from_uint! { i128, u128 }
89impl_int_from_uint! { isize, usize }
90
91macro_rules! impl_nzint {
92    ($ty:ty, $new:path) => {
93        impl Distribution<$ty> for Standard {
94            fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> $ty {
95                loop {
96                    if let Some(nz) = $new(rng.gen()) {
97                        break nz;
98                    }
99                }
100            }
101        }
102    };
103}
104
105impl_nzint!(NonZeroU8, NonZeroU8::new);
106impl_nzint!(NonZeroU16, NonZeroU16::new);
107impl_nzint!(NonZeroU32, NonZeroU32::new);
108impl_nzint!(NonZeroU64, NonZeroU64::new);
109impl_nzint!(NonZeroU128, NonZeroU128::new);
110impl_nzint!(NonZeroUsize, NonZeroUsize::new);
111
112#[cfg(feature = "simd_support")]
113macro_rules! simd_impl {
114    ($(($intrinsic:ident, $vec:ty),)+) => {$(
115        impl Distribution<$intrinsic> for Standard {
116            #[inline]
117            fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> $intrinsic {
118                $intrinsic::from_bits(rng.gen::<$vec>())
119            }
120        }
121    )+};
122
123    ($bits:expr,) => {};
124    ($bits:expr, $ty:ty, $($ty_more:ty,)*) => {
125        simd_impl!($bits, $($ty_more,)*);
126
127        impl Distribution<$ty> for Standard {
128            #[inline]
129            fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> $ty {
130                let mut vec: $ty = Default::default();
131                unsafe {
132                    let ptr = &mut vec;
133                    let b_ptr = &mut *(ptr as *mut $ty as *mut [u8; $bits/8]);
134                    rng.fill_bytes(b_ptr);
135                }
136                vec.to_le()
137            }
138        }
139    };
140}
141
142#[cfg(feature = "simd_support")]
143simd_impl!(16, u8x2, i8x2,);
144#[cfg(feature = "simd_support")]
145simd_impl!(32, u8x4, i8x4, u16x2, i16x2,);
146#[cfg(feature = "simd_support")]
147simd_impl!(64, u8x8, i8x8, u16x4, i16x4, u32x2, i32x2,);
148#[cfg(feature = "simd_support")]
149simd_impl!(128, u8x16, i8x16, u16x8, i16x8, u32x4, i32x4, u64x2, i64x2,);
150#[cfg(feature = "simd_support")]
151simd_impl!(256, u8x32, i8x32, u16x16, i16x16, u32x8, i32x8, u64x4, i64x4,);
152#[cfg(feature = "simd_support")]
153simd_impl!(512, u8x64, i8x64, u16x32, i16x32, u32x16, i32x16, u64x8, i64x8,);
154#[cfg(all(
155    feature = "simd_support",
156    any(target_arch = "x86", target_arch = "x86_64")
157))]
158simd_impl!((__m128i, u8x16), (__m256i, u8x32),);
159
160#[cfg(test)]
161mod tests {
162    use super::*;
163
164    #[test]
165    fn test_integers() {
166        let mut rng = crate::test::rng(806);
167
168        rng.sample::<isize, _>(Standard);
169        rng.sample::<i8, _>(Standard);
170        rng.sample::<i16, _>(Standard);
171        rng.sample::<i32, _>(Standard);
172        rng.sample::<i64, _>(Standard);
173        rng.sample::<i128, _>(Standard);
174
175        rng.sample::<usize, _>(Standard);
176        rng.sample::<u8, _>(Standard);
177        rng.sample::<u16, _>(Standard);
178        rng.sample::<u32, _>(Standard);
179        rng.sample::<u64, _>(Standard);
180        rng.sample::<u128, _>(Standard);
181    }
182
183    #[test]
184    fn value_stability() {
185        fn test_samples<T: Copy + core::fmt::Debug + PartialEq>(zero: T, expected: &[T])
186        where Standard: Distribution<T> {
187            let mut rng = crate::test::rng(807);
188            let mut buf = [zero; 3];
189            for x in &mut buf {
190                *x = rng.sample(Standard);
191            }
192            assert_eq!(&buf, expected);
193        }
194
195        test_samples(0u8, &[9, 247, 111]);
196        test_samples(0u16, &[32265, 42999, 38255]);
197        test_samples(0u32, &[2220326409, 2575017975, 2018088303]);
198        test_samples(0u64, &[
199            11059617991457472009,
200            16096616328739788143,
201            1487364411147516184,
202        ]);
203        test_samples(0u128, &[
204            296930161868957086625409848350820761097,
205            145644820879247630242265036535529306392,
206            111087889832015897993126088499035356354,
207        ]);
208        #[cfg(any(target_pointer_width = "32", target_pointer_width = "16"))]
209        test_samples(0usize, &[2220326409, 2575017975, 2018088303]);
210        #[cfg(target_pointer_width = "64")]
211        test_samples(0usize, &[
212            11059617991457472009,
213            16096616328739788143,
214            1487364411147516184,
215        ]);
216
217        test_samples(0i8, &[9, -9, 111]);
218        // Skip further i* types: they are simple reinterpretation of u* samples
219
220        #[cfg(feature = "simd_support")]
221        {
222            // We only test a sub-set of types here and make assumptions about the rest.
223
224            test_samples(u8x2::default(), &[
225                u8x2::new(9, 126),
226                u8x2::new(247, 167),
227                u8x2::new(111, 149),
228            ]);
229            test_samples(u8x4::default(), &[
230                u8x4::new(9, 126, 87, 132),
231                u8x4::new(247, 167, 123, 153),
232                u8x4::new(111, 149, 73, 120),
233            ]);
234            test_samples(u8x8::default(), &[
235                u8x8::new(9, 126, 87, 132, 247, 167, 123, 153),
236                u8x8::new(111, 149, 73, 120, 68, 171, 98, 223),
237                u8x8::new(24, 121, 1, 50, 13, 46, 164, 20),
238            ]);
239
240            test_samples(i64x8::default(), &[
241                i64x8::new(
242                    -7387126082252079607,
243                    -2350127744969763473,
244                    1487364411147516184,
245                    7895421560427121838,
246                    602190064936008898,
247                    6022086574635100741,
248                    -5080089175222015595,
249                    -4066367846667249123,
250                ),
251                i64x8::new(
252                    9180885022207963908,
253                    3095981199532211089,
254                    6586075293021332726,
255                    419343203796414657,
256                    3186951873057035255,
257                    5287129228749947252,
258                    444726432079249540,
259                    -1587028029513790706,
260                ),
261                i64x8::new(
262                    6075236523189346388,
263                    1351763722368165432,
264                    -6192309979959753740,
265                    -7697775502176768592,
266                    -4482022114172078123,
267                    7522501477800909500,
268                    -1837258847956201231,
269                    -586926753024886735,
270                ),
271            ]);
272        }
273    }
274}
rand/distributions/integer.rs

rand/distributions/
integer.rs
