diff options
Diffstat (limited to 'vendor/compiler_builtins/libm/src/math/rem_pio2f.rs')
-rw-r--r-- | vendor/compiler_builtins/libm/src/math/rem_pio2f.rs | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/rem_pio2f.rs b/vendor/compiler_builtins/libm/src/math/rem_pio2f.rs new file mode 100644 index 000000000..775f5d750 --- /dev/null +++ b/vendor/compiler_builtins/libm/src/math/rem_pio2f.rs @@ -0,0 +1,67 @@ +/* origin: FreeBSD /usr/src/lib/msun/src/e_rem_pio2f.c */ +/* + * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. + * Debugged and optimized by Bruce D. Evans. + */ +/* + * ==================================================== + * 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 super::rem_pio2_large; + +use core::f64; + +const TOINT: f64 = 1.5 / f64::EPSILON; + +/// 53 bits of 2/pi +const INV_PIO2: f64 = 6.36619772367581382433e-01; /* 0x3FE45F30, 0x6DC9C883 */ +/// first 25 bits of pi/2 +const PIO2_1: f64 = 1.57079631090164184570e+00; /* 0x3FF921FB, 0x50000000 */ +/// pi/2 - pio2_1 +const PIO2_1T: f64 = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */ + +/// Return the remainder of x rem pi/2 in *y +/// +/// use double precision for everything except passing x +/// use __rem_pio2_large() for large x +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub(crate) fn rem_pio2f(x: f32) -> (i32, f64) { + let x64 = x as f64; + + let mut tx: [f64; 1] = [0.]; + let mut ty: [f64; 1] = [0.]; + + let ix = x.to_bits() & 0x7fffffff; + /* 25+53 bit pi is good enough for medium size */ + if ix < 0x4dc90fdb { + /* |x| ~< 2^28*(pi/2), medium size */ + /* Use a specialized rint() to get fn. Assume round-to-nearest. */ + let tmp = x64 * INV_PIO2 + TOINT; + // force rounding of tmp to it's storage format on x87 to avoid + // excess precision issues. + #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] + let tmp = force_eval!(tmp); + let f_n = tmp - TOINT; + return (f_n as i32, x64 - f_n * PIO2_1 - f_n * PIO2_1T); + } + if ix >= 0x7f800000 { + /* x is inf or NaN */ + return (0, x64 - x64); + } + /* scale x into [2^23, 2^24-1] */ + let sign = (x.to_bits() >> 31) != 0; + let e0 = ((ix >> 23) - (0x7f + 23)) as i32; /* e0 = ilogb(|x|)-23, positive */ + tx[0] = f32::from_bits(ix - (e0 << 23) as u32) as f64; + let n = rem_pio2_large(&tx, &mut ty, e0, 0); + if sign { + return (-n, -ty[0]); + } + (n, ty[0]) +} |