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Add nextafter and nextafterf from musl

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This commit is contained in:
gnzlbg 2019-07-09 17:17:08 +02:00
parent 36b5b4c00c
commit 2da2f8dce4
3 changed files with 80 additions and 0 deletions
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4
library/compiler-builtins/libm/src/math/mod.rs
View file

@ -146,6 +146,8 @@ mod log2f;
mod logf;
mod modf;
mod modff;
mod nextafter;
mod nextafterf;
mod pow;
mod powf;
mod remainder;
@ -258,6 +260,8 @@ pub use self::log2f::log2f;
pub use self::logf::logf;
pub use self::modf::modf;
pub use self::modff::modff;
pub use self::nextafter::nextafter;
pub use self::nextafterf::nextafterf;
pub use self::pow::pow;
pub use self::powf::powf;
pub use self::remainder::remainder;

38
library/compiler-builtins/libm/src/math/nextafter.rs Normal file
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@ -0,0 +1,38 @@
#[inline]
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn nextafter(x: f64, y: f64) -> f64 {
if x.is_nan() || y.is_nan() {
return x + y;
}
let mut ux_i = x.to_bits();
let uy_i = y.to_bits();
if ux_i == uy_i {
return y;
}
let ax = ux_i & !1_u64 / 2;
let ay = uy_i & !1_u64 / 2;
if ax == 0 {
if ay == 0 {
return y;
}
ux_i = (uy_i & 1_u64 << 63) | 1;
} else if ax > ay || ((ux_i ^ uy_i) & 1_u64 << 63) != 0 {
ux_i -= 1;
} else {
ux_i += 1;
}
let e = ux_i.wrapping_shr(52 & 0x7ff);
// raise overflow if ux.f is infinite and x is finite
if e == 0x7ff {
force_eval!(x + x);
}
let ux_f = f64::from_bits(ux_i);
// raise underflow if ux.f is subnormal or zero
if e == 0 {
force_eval!(x * x + ux_f * ux_f);
}
ux_f
}

38
library/compiler-builtins/libm/src/math/nextafterf.rs Normal file
View file

@ -0,0 +1,38 @@
#[inline]
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn nextafterf(x: f32, y: f32) -> f32 {
if x.is_nan() || y.is_nan() {
return x + y;
}
let mut ux_i = x.to_bits();
let uy_i = y.to_bits();
if ux_i == uy_i {
return y;
}
let ax = ux_i & 0x7fff_ffff_u32;
let ay = uy_i & 0x7fff_ffff_u32;
if ax == 0 {
if ay == 0 {
return y;
}
ux_i = (uy_i & 0x8000_0000_u32) | 1;
} else if ax > ay || ((ux_i ^ uy_i) & 0x8000_0000_u32) != 0 {
ux_i -= 1;
} else {
ux_i += 1;
}
let e = ux_i.wrapping_shr(0x7f80_0000_u32);
// raise overflow if ux_f is infinite and x is finite
if e == 0x7f80_0000_u32 {
force_eval!(x + x);
}
let ux_f = f32::from_bits(ux_i);
// raise underflow if ux_f is subnormal or zero
if e == 0 {
force_eval!(x * x + ux_f * ux_f);
}
ux_f
}