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
17use super::{k_cosf, k_sinf, rem_pio2f};
18
19/* Small multiples of pi/2 rounded to double precision. */
20const PI_2: f64 = 0.5 * 3.1415926535897931160E+00;
21const S1PIO2: f64 = 1.0 * PI_2; /* 0x3FF921FB, 0x54442D18 */
22const S2PIO2: f64 = 2.0 * PI_2; /* 0x400921FB, 0x54442D18 */
23const S3PIO2: f64 = 3.0 * PI_2; /* 0x4012D97C, 0x7F3321D2 */
24const S4PIO2: f64 = 4.0 * PI_2; /* 0x401921FB, 0x54442D18 */
25
26/// Both the sine and cosine of `x` (f32).
27///
28/// `x` is specified in radians and the return value is (sin(x), cos(x)).
29#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
30pub fn sincosf(x: f32) -> (f32, f32) {
31 let s: f32;
32 let c: f32;
33 let mut ix: u32;
34 let sign: bool;
35
36 ix = x.to_bits();
37 sign = (ix >> 31) != 0;
38 ix &= 0x7fffffff;
39
40 /* |x| ~<= pi/4 */
41 if ix <= 0x3f490fda {
42 /* |x| < 2**-12 */
43 if ix < 0x39800000 {
44 /* raise inexact if x!=0 and underflow if subnormal */
45
46 let x1p120 = f32::from_bits(0x7b800000); // 0x1p120 == 2^120
47 if ix < 0x00100000 {
48 force_eval!(x / x1p120);
49 } else {
50 force_eval!(x + x1p120);
51 }
52 return (x, 1.0);
53 }
54 return (k_sinf(x as f64), k_cosf(x as f64));
55 }
56
57 /* |x| ~<= 5*pi/4 */
58 if ix <= 0x407b53d1 {
59 if ix <= 0x4016cbe3 {
60 /* |x| ~<= 3pi/4 */
61 if sign {
62 s = -k_cosf(x as f64 + S1PIO2);
63 c = k_sinf(x as f64 + S1PIO2);
64 } else {
65 s = k_cosf(S1PIO2 - x as f64);
66 c = k_sinf(S1PIO2 - x as f64);
67 }
68 }
69 /* -sin(x+c) is not correct if x+c could be 0: -0 vs +0 */
70 else if sign {
71 s = -k_sinf(x as f64 + S2PIO2);
72 c = -k_cosf(x as f64 + S2PIO2);
73 } else {
74 s = -k_sinf(x as f64 - S2PIO2);
75 c = -k_cosf(x as f64 - S2PIO2);
76 }
77
78 return (s, c);
79 }
80
81 /* |x| ~<= 9*pi/4 */
82 if ix <= 0x40e231d5 {
83 if ix <= 0x40afeddf {
84 /* |x| ~<= 7*pi/4 */
85 if sign {
86 s = k_cosf(x as f64 + S3PIO2);
87 c = -k_sinf(x as f64 + S3PIO2);
88 } else {
89 s = -k_cosf(x as f64 - S3PIO2);
90 c = k_sinf(x as f64 - S3PIO2);
91 }
92 } else if sign {
93 s = k_sinf(x as f64 + S4PIO2);
94 c = k_cosf(x as f64 + S4PIO2);
95 } else {
96 s = k_sinf(x as f64 - S4PIO2);
97 c = k_cosf(x as f64 - S4PIO2);
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// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
126#[cfg(not(target_arch = "powerpc64"))]
127#[cfg(test)]
128mod tests {
129 use super::sincosf;
130
131 #[test]
132 fn rotational_symmetry() {
133 use core::f32::consts::PI;
134 const N: usize = 24;
135 for n in 0..N {
136 let theta = 2. * PI * (n as f32) / (N as f32);
137 let (s, c) = sincosf(theta);
138 let (s_plus, c_plus) = sincosf(theta + 2. * PI);
139 let (s_minus, c_minus) = sincosf(theta - 2. * PI);
140
141 const TOLERANCE: f32 = 1e-6;
142 assert!(
143 (s - s_plus).abs() < TOLERANCE,
144 "|{} - {}| = {} >= {}",
145 s,
146 s_plus,
147 (s - s_plus).abs(),
148 TOLERANCE
149 );
150 assert!(
151 (s - s_minus).abs() < TOLERANCE,
152 "|{} - {}| = {} >= {}",
153 s,
154 s_minus,
155 (s - s_minus).abs(),
156 TOLERANCE
157 );
158 assert!(
159 (c - c_plus).abs() < TOLERANCE,
160 "|{} - {}| = {} >= {}",
161 c,
162 c_plus,
163 (c - c_plus).abs(),
164 TOLERANCE
165 );
166 assert!(
167 (c - c_minus).abs() < TOLERANCE,
168 "|{} - {}| = {} >= {}",
169 c,
170 c_minus,
171 (c - c_minus).abs(),
172 TOLERANCE
173 );
174 }
175 }
176}
177