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 /* Small multiples of pi/2 rounded to double precision. */
20 const PI_2: f32 = 0.5 * 3.1415926535897931160E+00;
21 const S1PIO2: f32 = 1.0 * PI_2; /* 0x3FF921FB, 0x54442D18 */
22 const S2PIO2: f32 = 2.0 * PI_2; /* 0x400921FB, 0x54442D18 */
23 const S3PIO2: f32 = 3.0 * PI_2; /* 0x4012D97C, 0x7F3321D2 */
24 const S4PIO2: f32 = 4.0 * PI_2; /* 0x401921FB, 0x54442D18 */
25
sincosf(x: f32) -> (f32, f32)26 pub fn sincosf(x: f32) -> (f32, f32) {
27 let s: f32;
28 let c: f32;
29 let mut ix: u32;
30 let sign: bool;
31
32 ix = x.to_bits();
33 sign = (ix >> 31) != 0;
34 ix &= 0x7fffffff;
35
36 /* |x| ~<= pi/4 */
37 if ix <= 0x3f490fda {
38 /* |x| < 2**-12 */
39 if ix < 0x39800000 {
40 /* raise inexact if x!=0 and underflow if subnormal */
41
42 let x1p120 = f32::from_bits(0x7b800000); // 0x1p120 == 2^120
43 if ix < 0x00100000 {
44 force_eval!(x / x1p120);
45 } else {
46 force_eval!(x + x1p120);
47 }
48 return (x, 1.0);
49 }
50 return (k_sinf(x as f64), k_cosf(x as f64));
51 }
52
53 /* |x| ~<= 5*pi/4 */
54 if ix <= 0x407b53d1 {
55 if ix <= 0x4016cbe3 {
56 /* |x| ~<= 3pi/4 */
57 if sign {
58 s = -k_cosf((x + S1PIO2) as f64);
59 c = k_sinf((x + S1PIO2) as f64);
60 } else {
61 s = k_cosf((S1PIO2 - x) as f64);
62 c = k_sinf((S1PIO2 - x) as f64);
63 }
64 }
65 /* -sin(x+c) is not correct if x+c could be 0: -0 vs +0 */
66 else {
67 if sign {
68 s = -k_sinf((x + S2PIO2) as f64);
69 c = -k_cosf((x + S2PIO2) as f64);
70 } else {
71 s = -k_sinf((x - S2PIO2) as f64);
72 c = -k_cosf((x - S2PIO2) as f64);
73 }
74 }
75
76 return (s, c);
77 }
78
79 /* |x| ~<= 9*pi/4 */
80 if ix <= 0x40e231d5 {
81 if ix <= 0x40afeddf {
82 /* |x| ~<= 7*pi/4 */
83 if sign {
84 s = k_cosf((x + S3PIO2) as f64);
85 c = -k_sinf((x + S3PIO2) as f64);
86 } else {
87 s = -k_cosf((x - S3PIO2) as f64);
88 c = k_sinf((x - S3PIO2) as f64);
89 }
90 } else {
91 if sign {
92 s = k_sinf((x + S4PIO2) as f64);
93 c = k_cosf((x + S4PIO2) as f64);
94 } else {
95 s = k_sinf((x - S4PIO2) as f64);
96 c = k_cosf((x - S4PIO2) as f64);
97 }
98 }
99
100 return (s, c);
101 }
102
103 /* sin(Inf or NaN) is NaN */
104 if ix >= 0x7f800000 {
105 let rv = x - x;
106 return (rv, rv);
107 }
108
109 /* general argument reduction needed */
110 let (n, y) = rem_pio2f(x);
111 s = k_sinf(y);
112 c = k_cosf(y);
113 match n & 3 {
114 0 => (s, c),
115 1 => (c, -s),
116 2 => (-s, -c),
117 3 => (-c, s),
118 #[cfg(debug_assertions)]
119 _ => unreachable!(),
120 #[cfg(not(debug_assertions))]
121 _ => (0.0, 1.0),
122 }
123 }
124
125 #[cfg(test)]
126 mod tests {
127 use super::sincosf;
128 use crate::_eqf;
129
130 #[test]
with_pi()131 fn with_pi() {
132 let (s, c) = sincosf(core::f32::consts::PI);
133 _eqf(s.abs(), 0.0).unwrap();
134 _eqf(c, -1.0).unwrap();
135 }
136
137 #[test]
rotational_symmetry()138 fn rotational_symmetry() {
139 use core::f32::consts::PI;
140 const N: usize = 24;
141 for n in 0..N {
142 let theta = 2. * PI * (n as f32) / (N as f32);
143 let (s, c) = sincosf(theta);
144 let (s_plus, c_plus) = sincosf(theta + 2. * PI);
145 let (s_minus, c_minus) = sincosf(theta - 2. * PI);
146
147 const TOLERANCE: f32 = 1e-6;
148 assert!((s - s_plus).abs() < TOLERANCE);
149 assert!((s - s_minus).abs() < TOLERANCE);
150 assert!((c - c_plus).abs() < TOLERANCE);
151 assert!((c - c_minus).abs() < TOLERANCE);
152 }
153 }
154 }
155