compiler_builtins/math/libm_math/
sinf.rs

1/* origin: FreeBSD /usr/src/lib/msun/src/s_sinf.c */
2/*
3 * Conversion to float by Ian Lance Taylor, Cygnus Support, [email protected].
4 * Optimized by Bruce D. Evans.
5 */
6/*
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 *
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
13 * is preserved.
14 * ====================================================
15 */
16
17use core::f64::consts::FRAC_PI_2;
18
19use super::{k_cosf, k_sinf, rem_pio2f};
20
21/* Small multiples of pi/2 rounded to double precision. */
22const S1_PIO2: f64 = 1. * FRAC_PI_2; /* 0x3FF921FB, 0x54442D18 */
23const S2_PIO2: f64 = 2. * FRAC_PI_2; /* 0x400921FB, 0x54442D18 */
24const S3_PIO2: f64 = 3. * FRAC_PI_2; /* 0x4012D97C, 0x7F3321D2 */
25const S4_PIO2: f64 = 4. * FRAC_PI_2; /* 0x401921FB, 0x54442D18 */
26
27/// The sine of `x` (f32).
28///
29/// `x` is specified in radians.
30#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
31pub fn sinf(x: f32) -> f32 {
32    let x64 = x as f64;
33
34    let x1p120 = f32::from_bits(0x7b800000); // 0x1p120f === 2 ^ 120
35
36    let mut ix = x.to_bits();
37    let sign = (ix >> 31) != 0;
38    ix &= 0x7fffffff;
39
40    if ix <= 0x3f490fda {
41        /* |x| ~<= pi/4 */
42        if ix < 0x39800000 {
43            /* |x| < 2**-12 */
44            /* raise inexact if x!=0 and underflow if subnormal */
45            force_eval!(if ix < 0x00800000 {
46                x / x1p120
47            } else {
48                x + x1p120
49            });
50            return x;
51        }
52        return k_sinf(x64);
53    }
54    if ix <= 0x407b53d1 {
55        /* |x| ~<= 5*pi/4 */
56        if ix <= 0x4016cbe3 {
57            /* |x| ~<= 3pi/4 */
58            if sign {
59                return -k_cosf(x64 + S1_PIO2);
60            } else {
61                return k_cosf(x64 - S1_PIO2);
62            }
63        }
64        return k_sinf(if sign {
65            -(x64 + S2_PIO2)
66        } else {
67            -(x64 - S2_PIO2)
68        });
69    }
70    if ix <= 0x40e231d5 {
71        /* |x| ~<= 9*pi/4 */
72        if ix <= 0x40afeddf {
73            /* |x| ~<= 7*pi/4 */
74            if sign {
75                return k_cosf(x64 + S3_PIO2);
76            } else {
77                return -k_cosf(x64 - S3_PIO2);
78            }
79        }
80        return k_sinf(if sign { x64 + S4_PIO2 } else { x64 - S4_PIO2 });
81    }
82
83    /* sin(Inf or NaN) is NaN */
84    if ix >= 0x7f800000 {
85        return x - x;
86    }
87
88    /* general argument reduction needed */
89    let (n, y) = rem_pio2f(x);
90    match n & 3 {
91        0 => k_sinf(y),
92        1 => k_cosf(y),
93        2 => k_sinf(-y),
94        _ => -k_cosf(y),
95    }
96}
compiler_builtins/math/libm_math/sinf.rs

compiler_builtins/math/libm_math/
sinf.rs
