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#include "libm.h"
18
19/* Small multiples of pi/2 rounded to double precision. */
20static const double
21s1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
22s2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
23s3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
24s4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
25
26float sinf(float x)
27{
28	double y;
29	uint32_t ix;
30	int n, sign;
31
32	GET_FLOAT_WORD(ix, x);
33	sign = ix >> 31;
34	ix &= 0x7fffffff;
35
36	if (ix <= 0x3f490fda) {  /* |x| ~<= pi/4 */
37		if (ix < 0x39800000) {  /* |x| < 2**-12 */
38			/* raise inexact if x!=0 and underflow if subnormal */
39			FORCE_EVAL(ix < 0x00800000 ? x/0x1p120f : x+0x1p120f);
40			return x;
41		}
42		return __sindf(x);
43	}
44	if (ix <= 0x407b53d1) {  /* |x| ~<= 5*pi/4 */
45		if (ix <= 0x4016cbe3) {  /* |x| ~<= 3pi/4 */
46			if (sign)
47				return -__cosdf(x + s1pio2);
48			else
49				return __cosdf(x - s1pio2);
50		}
51		return __sindf(sign ? -(x + s2pio2) : -(x - s2pio2));
52	}
53	if (ix <= 0x40e231d5) {  /* |x| ~<= 9*pi/4 */
54		if (ix <= 0x40afeddf) {  /* |x| ~<= 7*pi/4 */
55			if (sign)
56				return __cosdf(x + s3pio2);
57			else
58				return -__cosdf(x - s3pio2);
59		}
60		return __sindf(sign ? x + s4pio2 : x - s4pio2);
61	}
62
63	/* sin(Inf or NaN) is NaN */
64	if (ix >= 0x7f800000)
65		return x - x;
66
67	/* general argument reduction needed */
68	n = __rem_pio2f(x, &y);
69	switch (n&3) {
70	case 0: return  __sindf(y);
71	case 1: return  __cosdf(y);
72	case 2: return  __sindf(-y);
73	default:
74		return -__cosdf(y);
75	}
76}
77