1/* origin: FreeBSD /usr/src/lib/msun/src/s_cosf.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
21c1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
22c2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
23c3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
24c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
25
26float cosf(float x)
27{
28	double y;
29	uint32_t ix;
30	unsigned 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 */
39			FORCE_EVAL(x + 0x1p120f);
40			return 1.0f;
41		}
42		return __cosdf(x);
43	}
44	if (ix <= 0x407b53d1) {  /* |x| ~<= 5*pi/4 */
45		if (ix > 0x4016cbe3)  /* |x|  ~> 3*pi/4 */
46			return -__cosdf(sign ? x+c2pio2 : x-c2pio2);
47		else {
48			if (sign)
49				return __sindf(x + c1pio2);
50			else
51				return __sindf(c1pio2 - x);
52		}
53	}
54	if (ix <= 0x40e231d5) {  /* |x| ~<= 9*pi/4 */
55		if (ix > 0x40afeddf)  /* |x| ~> 7*pi/4 */
56			return __cosdf(sign ? x+c4pio2 : x-c4pio2);
57		else {
58			if (sign)
59				return __sindf(-x - c3pio2);
60			else
61				return __sindf(x - c3pio2);
62		}
63	}
64
65	/* cos(Inf or NaN) is NaN */
66	if (ix >= 0x7f800000)
67		return x-x;
68
69	/* general argument reduction needed */
70	n = __rem_pio2f(x,&y);
71	switch (n&3) {
72	case 0: return  __cosdf(y);
73	case 1: return  __sindf(-y);
74	case 2: return -__cosdf(y);
75	default:
76		return  __sindf(y);
77	}
78}
79