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Add saturating abs/neg

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Jubilee Young 2021-04-02 08:28:48 -07:00
parent 4a6b4c0a2e
commit dd1a5e41ad
1 changed files with 35 additions and 0 deletions
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35
crates/core_simd/src/math.rs
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@ -78,6 +78,41 @@ macro_rules! impl_int_arith {
pub fn saturating_sub(self, second: Self) -> Self {
unsafe { crate::intrinsics::simd_saturating_sub(self, second) }
}
/// Lanewise saturating absolute value, implemented in Rust.
///
/// # Examples
/// # use core_simd::*;
#[doc = concat!("# use core::", stringify!($n), "::{MIN, MAX};")]
#[doc = concat!("let x = ", stringify!($name), "::splat([MIN, -2, 0, 3]);")]
/// let unsat = x.abs();
/// let sat = x.saturating_abs();
#[doc = concat!("assert_eq!(unsat, ", stringify!($name), "::from_array([MIN, 2, 0, 3]);")]
#[doc = concat!("assert_eq!(sat, ", stringify!($name), "::from_array([MAX, 2, 0, 3]));")]
/// ```
#[inline]
pub fn saturating_abs(self) -> Self {
// arith shift for -1 or 0 mask based on sign bit, giving 2s complement
const SHR: $n = <$n>::BITS as $n - 1;
let m = self >> SHR;
(self^m).saturating_sub(m)
}
/// Lanewise saturating negation, implemented in Rust.
///
/// # Examples
/// # use core_simd::*;
#[doc = concat!("# use core::", stringify!($n), "::{MIN, MAX};")]
#[doc = concat!("let x = ", stringify!($name), "::splat([MIN, -2, 3, MAX]);")]
/// let unsat = -x;
/// let sat = x.saturating_neg();
#[doc = concat!("assert_eq!(unsat, ", stringify!($name), "::from_array([MIN, 2, -3, MIN + 1]);")]
#[doc = concat!("assert_eq!(sat, ", stringify!($name), "::from_array([MAX, 2, -3, MIN + 1]));")]
/// ```
#[inline]
pub fn saturating_neg(self) -> Self {
Self::splat(0).saturating_sub(self)
}
})+
}
}