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