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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 02:49:50 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 02:49:50 +0000 |
commit | 9835e2ae736235810b4ea1c162ca5e65c547e770 (patch) | |
tree | 3fcebf40ed70e581d776a8a4c65923e8ec20e026 /vendor/libm-0.1.4/src/math/log1pf.rs | |
parent | Releasing progress-linux version 1.70.0+dfsg2-1~progress7.99u1. (diff) | |
download | rustc-9835e2ae736235810b4ea1c162ca5e65c547e770.tar.xz rustc-9835e2ae736235810b4ea1c162ca5e65c547e770.zip |
Merging upstream version 1.71.1+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/libm-0.1.4/src/math/log1pf.rs')
-rw-r--r-- | vendor/libm-0.1.4/src/math/log1pf.rs | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/vendor/libm-0.1.4/src/math/log1pf.rs b/vendor/libm-0.1.4/src/math/log1pf.rs new file mode 100644 index 000000000..8e9651357 --- /dev/null +++ b/vendor/libm-0.1.4/src/math/log1pf.rs @@ -0,0 +1,99 @@ +/* origin: FreeBSD /usr/src/lib/msun/src/s_log1pf.c */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +use core::f32; + +const LN2_HI: f32 = 6.9313812256e-01; /* 0x3f317180 */ +const LN2_LO: f32 = 9.0580006145e-06; /* 0x3717f7d1 */ +/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */ +const LG1: f32 = 0.66666662693; /* 0xaaaaaa.0p-24 */ +const LG2: f32 = 0.40000972152; /* 0xccce13.0p-25 */ +const LG3: f32 = 0.28498786688; /* 0x91e9ee.0p-25 */ +const LG4: f32 = 0.24279078841; /* 0xf89e26.0p-26 */ + +#[inline] +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub fn log1pf(x: f32) -> f32 { + let mut ui: u32 = x.to_bits(); + let hfsq: f32; + let mut f: f32 = 0.; + let mut c: f32 = 0.; + let s: f32; + let z: f32; + let r: f32; + let w: f32; + let t1: f32; + let t2: f32; + let dk: f32; + let ix: u32; + let mut iu: u32; + let mut k: i32; + + ix = ui; + k = 1; + if ix < 0x3ed413d0 || (ix >> 31) > 0 { + /* 1+x < sqrt(2)+ */ + if ix >= 0xbf800000 { + /* x <= -1.0 */ + if x == -1. { + return x / 0.0; /* log1p(-1)=+inf */ + } + return (x - x) / 0.0; /* log1p(x<-1)=NaN */ + } + if ix << 1 < 0x33800000 << 1 { + /* |x| < 2**-24 */ + /* underflow if subnormal */ + if (ix & 0x7f800000) == 0 { + force_eval!(x * x); + } + return x; + } + if ix <= 0xbe95f619 { + /* sqrt(2)/2- <= 1+x < sqrt(2)+ */ + k = 0; + c = 0.; + f = x; + } + } else if ix >= 0x7f800000 { + return x; + } + if k > 0 { + ui = (1. + x).to_bits(); + iu = ui; + iu += 0x3f800000 - 0x3f3504f3; + k = (iu >> 23) as i32 - 0x7f; + /* correction term ~ log(1+x)-log(u), avoid underflow in c/u */ + if k < 25 { + c = if k >= 2 { + 1. - (f32::from_bits(ui) - x) + } else { + x - (f32::from_bits(ui) - 1.) + }; + c /= f32::from_bits(ui); + } else { + c = 0.; + } + /* reduce u into [sqrt(2)/2, sqrt(2)] */ + iu = (iu & 0x007fffff) + 0x3f3504f3; + ui = iu; + f = f32::from_bits(ui) - 1.; + } + s = f / (2.0 + f); + z = s * s; + w = z * z; + t1 = w * (LG2 + w * LG4); + t2 = z * (LG1 + w * LG3); + r = t2 + t1; + hfsq = 0.5 * f * f; + dk = k as f32; + s * (hfsq + r) + (dk * LN2_LO + c) - hfsq + f + dk * LN2_HI +} |