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Introduce saturating math

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Jubilee Young 2021-03-28 18:44:16 -07:00
parent fa77b196c8
commit 4a6b4c0a2e
3 changed files with 97 additions and 0 deletions
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6
crates/core_simd/src/intrinsics.rs
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@ -62,4 +62,10 @@ extern "platform-intrinsic" {
pub(crate) fn simd_shuffle16<T, U>(x: T, y: T, idx: [u32; 16]) -> U;
pub(crate) fn simd_shuffle32<T, U>(x: T, y: T, idx: [u32; 32]) -> U;
pub(crate) fn simd_shuffle64<T, U>(x: T, y: T, idx: [u32; 64]) -> U;
// {s,u}add.sat
pub(crate) fn simd_saturating_add<T>(x: T, y: T) -> T;
// {s,u}sub.sat
pub(crate) fn simd_saturating_sub<T>(x: T, y: T) -> T;
}

3
crates/core_simd/src/lib.rs
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@ -1,6 +1,7 @@
#![no_std]
#![allow(incomplete_features)]
#![feature(repr_simd, platform_intrinsics, simd_ffi, const_generics)]
#![feature(extended_key_value_attributes)]
#![warn(missing_docs)]
//! Portable SIMD module.
@ -16,6 +17,8 @@ mod intrinsics;
mod ops;
mod round;
mod math;
mod lanes_at_most_64;
pub use lanes_at_most_64::LanesAtMost64;

88
crates/core_simd/src/math.rs Normal file
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@ -0,0 +1,88 @@
macro_rules! impl_uint_arith {
($(($name:ident, $n:ty)),+) => {
$( impl<const LANES: usize> $name<LANES> where Self: crate::LanesAtMost64 {
/// Lanewise saturating add.
///
/// # Examples
/// ```
/// # use core_simd::*;
#[doc = concat!("# use core::", stringify!($n), "::MAX;")]
#[doc = concat!("let x = ", stringify!($name), "::from_array([2, 1, 0, MAX]);")]
#[doc = concat!("let max = ", stringify!($name), "::splat(MAX);")]
/// let unsat = x + max;
/// let sat = x.saturating_add(max);
/// assert_eq!(x - 1, unsat);
/// assert_eq!(sat, max);
/// ```
#[inline]
pub fn saturating_add(self, second: Self) -> Self {
unsafe { crate::intrinsics::simd_saturating_add(self, second) }
}
/// Lanewise saturating subtract.
///
/// # Examples
/// ```
/// # use core_simd::*;
#[doc = concat!("# use core::", stringify!($n), "::MAX;")]
#[doc = concat!("let x = ", stringify!($name), "::from_array([2, 1, 0, MAX]);")]
#[doc = concat!("let max = ", stringify!($name), "::splat(MAX);")]
/// let unsat = x - max;
/// let sat = x.saturating_sub(max);
/// assert_eq!(unsat, x + 1);
#[doc = concat!("assert_eq!(sat, ", stringify!($name), "::splat(0));")]
#[inline]
pub fn saturating_sub(self, second: Self) -> Self {
unsafe { crate::intrinsics::simd_saturating_sub(self, second) }
}
})+
}
}
macro_rules! impl_int_arith {
($(($name:ident, $n:ty)),+) => {
$( impl<const LANES: usize> $name<LANES> where Self: crate::LanesAtMost64 {
/// Lanewise saturating add.
///
/// # Examples
/// ```
/// # use core_simd::*;
#[doc = concat!("# use core::", stringify!($n), "::{MIN, MAX};")]
#[doc = concat!("let x = ", stringify!($name), "::from_array([MIN, 0, 1, MAX]);")]
#[doc = concat!("let max = ", stringify!($name), "::splat(MAX);")]
/// let unsat = x + max;
/// let sat = x.saturating_add(max);
#[doc = concat!("assert_eq!(unsat, ", stringify!($name), "::from_array([-1, MAX, MIN, -2]));")]
#[doc = concat!("assert_eq!(sat, ", stringify!($name), "::from_array([-1, MAX, MAX, MAX]));")]
/// ```
#[inline]
pub fn saturating_add(self, second: Self) -> Self {
unsafe { crate::intrinsics::simd_saturating_add(self, second) }
}
/// Lanewise saturating subtract.
///
/// # Examples
/// ```
/// # use core_simd::*;
#[doc = concat!("# use core::", stringify!($n), "::{MIN, MAX};")]
#[doc = concat!("let x = ", stringify!($name), "::from_array([MIN, -2, -1, MAX]);")]
#[doc = concat!("let max = ", stringify!($name), "::splat(MAX);")]
/// let unsat = x - max;
/// let sat = x.saturating_sub(max);
#[doc = concat!("assert_eq!(unsat, ", stringify!($name), "::from_array([1, MAX, MIN, 0]));")]
#[doc = concat!("assert_eq!(sat, ", stringify!($name), "::from_array([MIN, MIN, MIN, 0]));")]
#[inline]
pub fn saturating_sub(self, second: Self) -> Self {
unsafe { crate::intrinsics::simd_saturating_sub(self, second) }
}
})+
}
}
use crate::vector::*;
impl_uint_arith! { (SimdU8, u8), (SimdU16, u16), (SimdU32, u32), (SimdU64, u64), (SimdUsize, usize) }
impl_int_arith! { (SimdI8, i8), (SimdI16, i16), (SimdI32, i32), (SimdI64, i64), (SimdIsize, isize) }