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1 | /* origin: FreeBSD /usr/src/lib/msun/src/s_sinf.c */ |
2 | /* | |
3 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. | |
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 | ||
17 | use super::{k_cosf, k_sinf, rem_pio2f}; | |
18 | ||
19 | use core::f64::consts::FRAC_PI_2; | |
20 | ||
21 | /* Small multiples of pi/2 rounded to double precision. */ | |
22 | const S1_PIO2: f64 = 1. * FRAC_PI_2; /* 0x3FF921FB, 0x54442D18 */ | |
23 | const S2_PIO2: f64 = 2. * FRAC_PI_2; /* 0x400921FB, 0x54442D18 */ | |
24 | const S3_PIO2: f64 = 3. * FRAC_PI_2; /* 0x4012D97C, 0x7F3321D2 */ | |
25 | const S4_PIO2: f64 = 4. * FRAC_PI_2; /* 0x401921FB, 0x54442D18 */ | |
26 | ||
48663c56 | 27 | #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
8faf50e0 XL |
28 | pub fn sinf(x: f32) -> f32 { |
29 | let x64 = x as f64; | |
30 | ||
31 | let x1p120 = f32::from_bits(0x7b800000); // 0x1p120f === 2 ^ 120 | |
32 | ||
33 | let mut ix = x.to_bits(); | |
34 | let sign = (ix >> 31) != 0; | |
35 | ix &= 0x7fffffff; | |
36 | ||
37 | if ix <= 0x3f490fda { | |
38 | /* |x| ~<= pi/4 */ | |
39 | if ix < 0x39800000 { | |
40 | /* |x| < 2**-12 */ | |
41 | /* raise inexact if x!=0 and underflow if subnormal */ | |
42 | force_eval!(if ix < 0x00800000 { | |
43 | x / x1p120 | |
44 | } else { | |
45 | x + x1p120 | |
46 | }); | |
47 | return x; | |
48 | } | |
49 | return k_sinf(x64); | |
50 | } | |
51 | if ix <= 0x407b53d1 { | |
52 | /* |x| ~<= 5*pi/4 */ | |
53 | if ix <= 0x4016cbe3 { | |
54 | /* |x| ~<= 3pi/4 */ | |
55 | if sign { | |
56 | return -k_cosf(x64 + S1_PIO2); | |
57 | } else { | |
58 | return k_cosf(x64 - S1_PIO2); | |
59 | } | |
60 | } | |
61 | return k_sinf(if sign { | |
62 | -(x64 + S2_PIO2) | |
63 | } else { | |
64 | -(x64 - S2_PIO2) | |
65 | }); | |
66 | } | |
67 | if ix <= 0x40e231d5 { | |
68 | /* |x| ~<= 9*pi/4 */ | |
69 | if ix <= 0x40afeddf { | |
70 | /* |x| ~<= 7*pi/4 */ | |
71 | if sign { | |
72 | return k_cosf(x64 + S3_PIO2); | |
73 | } else { | |
74 | return -k_cosf(x64 - S3_PIO2); | |
75 | } | |
76 | } | |
77 | return k_sinf(if sign { x64 + S4_PIO2 } else { x64 - S4_PIO2 }); | |
78 | } | |
79 | ||
80 | /* sin(Inf or NaN) is NaN */ | |
81 | if ix >= 0x7f800000 { | |
82 | return x - x; | |
83 | } | |
84 | ||
85 | /* general argument reduction needed */ | |
86 | let (n, y) = rem_pio2f(x); | |
87 | match n & 3 { | |
88 | 0 => k_sinf(y), | |
89 | 1 => k_cosf(y), | |
48663c56 | 90 | 2 => k_sinf(-y), |
8faf50e0 XL |
91 | _ => -k_cosf(y), |
92 | } | |
93 | } |