177 lines
5.0 KiB
Rust
177 lines
5.0 KiB
Rust
/* origin: FreeBSD /usr/src/lib/msun/src/s_sinf.c */
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/*
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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* Optimized by Bruce D. Evans.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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use super::{k_cosf, k_sinf, rem_pio2f};
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/* Small multiples of pi/2 rounded to double precision. */
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const PI_2: f64 = 0.5 * 3.1415926535897931160E+00;
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const S1PIO2: f64 = 1.0 * PI_2; /* 0x3FF921FB, 0x54442D18 */
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const S2PIO2: f64 = 2.0 * PI_2; /* 0x400921FB, 0x54442D18 */
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const S3PIO2: f64 = 3.0 * PI_2; /* 0x4012D97C, 0x7F3321D2 */
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const S4PIO2: f64 = 4.0 * PI_2; /* 0x401921FB, 0x54442D18 */
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/// Both the sine and cosine of `x` (f32).
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///
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/// `x` is specified in radians and the return value is (sin(x), cos(x)).
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#[cfg_attr(assert_no_panic, no_panic::no_panic)]
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pub fn sincosf(x: f32) -> (f32, f32) {
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let s: f32;
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let c: f32;
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let mut ix: u32;
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let sign: bool;
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ix = x.to_bits();
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sign = (ix >> 31) != 0;
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ix &= 0x7fffffff;
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/* |x| ~<= pi/4 */
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if ix <= 0x3f490fda {
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/* |x| < 2**-12 */
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if ix < 0x39800000 {
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/* raise inexact if x!=0 and underflow if subnormal */
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let x1p120 = f32::from_bits(0x7b800000); // 0x1p120 == 2^120
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if ix < 0x00100000 {
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force_eval!(x / x1p120);
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} else {
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force_eval!(x + x1p120);
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}
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return (x, 1.0);
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}
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return (k_sinf(x as f64), k_cosf(x as f64));
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}
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/* |x| ~<= 5*pi/4 */
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if ix <= 0x407b53d1 {
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if ix <= 0x4016cbe3 {
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/* |x| ~<= 3pi/4 */
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if sign {
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s = -k_cosf(x as f64 + S1PIO2);
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c = k_sinf(x as f64 + S1PIO2);
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} else {
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s = k_cosf(S1PIO2 - x as f64);
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c = k_sinf(S1PIO2 - x as f64);
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}
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}
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/* -sin(x+c) is not correct if x+c could be 0: -0 vs +0 */
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else if sign {
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s = -k_sinf(x as f64 + S2PIO2);
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c = -k_cosf(x as f64 + S2PIO2);
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} else {
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s = -k_sinf(x as f64 - S2PIO2);
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c = -k_cosf(x as f64 - S2PIO2);
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}
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return (s, c);
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}
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/* |x| ~<= 9*pi/4 */
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if ix <= 0x40e231d5 {
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if ix <= 0x40afeddf {
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/* |x| ~<= 7*pi/4 */
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if sign {
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s = k_cosf(x as f64 + S3PIO2);
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c = -k_sinf(x as f64 + S3PIO2);
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} else {
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s = -k_cosf(x as f64 - S3PIO2);
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c = k_sinf(x as f64 - S3PIO2);
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}
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} else if sign {
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s = k_sinf(x as f64 + S4PIO2);
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c = k_cosf(x as f64 + S4PIO2);
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} else {
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s = k_sinf(x as f64 - S4PIO2);
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c = k_cosf(x as f64 - S4PIO2);
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}
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return (s, c);
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}
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/* sin(Inf or NaN) is NaN */
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if ix >= 0x7f800000 {
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let rv = x - x;
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return (rv, rv);
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}
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/* general argument reduction needed */
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let (n, y) = rem_pio2f(x);
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s = k_sinf(y);
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c = k_cosf(y);
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match n & 3 {
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0 => (s, c),
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1 => (c, -s),
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2 => (-s, -c),
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3 => (-c, s),
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#[cfg(debug_assertions)]
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_ => unreachable!(),
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#[cfg(not(debug_assertions))]
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_ => (0.0, 1.0),
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}
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}
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// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
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#[cfg(not(target_arch = "powerpc64"))]
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#[cfg(test)]
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mod tests {
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use super::sincosf;
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#[test]
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fn rotational_symmetry() {
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use core::f32::consts::PI;
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const N: usize = 24;
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for n in 0..N {
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let theta = 2. * PI * (n as f32) / (N as f32);
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let (s, c) = sincosf(theta);
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let (s_plus, c_plus) = sincosf(theta + 2. * PI);
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let (s_minus, c_minus) = sincosf(theta - 2. * PI);
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const TOLERANCE: f32 = 1e-6;
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assert!(
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(s - s_plus).abs() < TOLERANCE,
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"|{} - {}| = {} >= {}",
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s,
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s_plus,
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(s - s_plus).abs(),
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TOLERANCE
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);
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assert!(
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(s - s_minus).abs() < TOLERANCE,
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"|{} - {}| = {} >= {}",
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s,
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s_minus,
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(s - s_minus).abs(),
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TOLERANCE
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);
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assert!(
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(c - c_plus).abs() < TOLERANCE,
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"|{} - {}| = {} >= {}",
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c,
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c_plus,
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(c - c_plus).abs(),
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TOLERANCE
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);
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assert!(
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(c - c_minus).abs() < TOLERANCE,
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"|{} - {}| = {} >= {}",
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c,
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c_minus,
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(c - c_minus).abs(),
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TOLERANCE
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);
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}
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}
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}
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