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 {
71 if sign {
72 s = -k_sinf(x as f64 + S2PIO2);
73 c = -k_cosf(x as f64 + S2PIO2);
74 } else {
75 s = -k_sinf(x as f64 - S2PIO2);
76 c = -k_cosf(x as f64 - S2PIO2);
77 }
78 }
79
80 return (s, c);
81 }
82
83 /* |x| ~<= 9*pi/4 */
84 if ix <= 0x40e231d5 {
85 if ix <= 0x40afeddf {
86 /* |x| ~<= 7*pi/4 */
87 if sign {
88 s = k_cosf(x as f64 + S3PIO2);
89 c = -k_sinf(x as f64 + S3PIO2);
90 } else {
91 s = -k_cosf(x as f64 - S3PIO2);
92 c = k_sinf(x as f64 - S3PIO2);
93 }
94 } else {
95 if sign {
96 s = k_sinf(x as f64 + S4PIO2);
97 c = k_cosf(x as f64 + S4PIO2);
98 } else {
99 s = k_sinf(x as f64 - S4PIO2);
100 c = k_cosf(x as f64 - S4PIO2);
101 }
102 }
103
104 return (s, c);
105 }
106
107 /* sin(Inf or NaN) is NaN */
108 if ix >= 0x7f800000 {
109 let rv = x - x;
110 return (rv, rv);
111 }
112
113 /* general argument reduction needed */
114 let (n, y) = rem_pio2f(x);
115 s = k_sinf(y);
116 c = k_cosf(y);
117 match n & 3 {
118 0 => (s, c),
119 1 => (c, -s),
120 2 => (-s, -c),
121 3 => (-c, s),
122 #[cfg(debug_assertions)]
123 _ => unreachable!(),
124 #[cfg(not(debug_assertions))]
125 _ => (0.0, 1.0),
126 }
127}
128
129// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
130#[cfg(not(target_arch = "powerpc64"))]
131#[cfg(test)]
132mod tests {
133 use super::sincosf;
134
135 #[test]
136 fn rotational_symmetry() {
137 use core::f32::consts::PI;
138 const N: usize = 24;
139 for n in 0..N {
140 let theta = 2. * PI * (n as f32) / (N as f32);
141 let (s, c) = sincosf(theta);
142 let (s_plus, c_plus) = sincosf(theta + 2. * PI);
143 let (s_minus, c_minus) = sincosf(theta - 2. * PI);
144
145 const TOLERANCE: f32 = 1e-6;
146 assert!(
147 (s - s_plus).abs() < TOLERANCE,
148 "|{} - {}| = {} >= {}",
149 s,
150 s_plus,
151 (s - s_plus).abs(),
152 TOLERANCE
153 );
154 assert!(
155 (s - s_minus).abs() < TOLERANCE,
156 "|{} - {}| = {} >= {}",
157 s,
158 s_minus,
159 (s - s_minus).abs(),
160 TOLERANCE
161 );
162 assert!(
163 (c - c_plus).abs() < TOLERANCE,
164 "|{} - {}| = {} >= {}",
165 c,
166 c_plus,
167 (c - c_plus).abs(),
168 TOLERANCE
169 );
170 assert!(
171 (c - c_minus).abs() < TOLERANCE,
172 "|{} - {}| = {} >= {}",
173 c,
174 c_minus,
175 (c - c_minus).abs(),
176 TOLERANCE
177 );
178 }
179 }
180}
181