s_cosf.c revision 152647 
1/* s_cosf.c -- float version of s_cos.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#ifndef lint
17static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_cosf.c 152647 2005-11-21 04:57:12Z bde $";
18#endif
19
20#include "math.h"
21#define	INLINE_KERNEL_COSF
22#define	INLINE_KERNEL_SINF
23#include "math_private.h"
24#include "k_cosf.c"
25#include "k_sinf.c"
26
27/* Small multiples of pi/2 rounded to double precision. */
28static const double
29c1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
30c2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
31c3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
32c4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
33
34static inline float
35__kernel_cosdf(double x)
36{
37	return __kernel_cosf((float)x, x - (float)x);
38}
39
40static inline float
41__kernel_sindf(double x)
42{
43	return __kernel_sinf((float)x, x - (float)x, 1);
44}
45
46float
47cosf(float x)
48{
49	float y[2];
50	int32_t n,ix;
51
52	x = fabsf(x);
53	GET_FLOAT_WORD(ix,x);
54
55	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
56	    if(ix<0x39800000)		/* |x| < 2**-12 */
57		if(((int)x)==0) return 1.0;	/* 1 with inexact if x != 0 */
58	    return __kernel_cosf(x,0.0);
59	}
60	if(ix<=0x407b53d1) {		/* |x| <= ~5*pi/4 */
61	    if(ix<=0x4016cbe3)		/* |x| <= ~3pi/4 */
62		return -__kernel_sindf(x - c1pio2);
63	    else
64		return -__kernel_cosdf(x - c2pio2);
65	}
66	if(ix<=0x40e231d5) {		/* |x| <= ~9*pi/4 */
67	    if(ix<=0x40afeddf)		/* |x| <= ~7*pi/4 */
68		return __kernel_sindf(x - c3pio2);
69	    else
70		return __kernel_cosdf(x - c4pio2);
71	}
72
73    /* cos(Inf or NaN) is NaN */
74	else if (ix>=0x7f800000) return x-x;
75
76    /* general argument reduction needed */
77	else {
78	    n = __ieee754_rem_pio2f(x,y);
79	    switch(n&3) {
80		case 0: return  __kernel_cosf(y[0],y[1]);
81		case 1: return -__kernel_sinf(y[0],y[1],1);
82		case 2: return -__kernel_cosf(y[0],y[1]);
83		default:
84		        return  __kernel_sinf(y[0],y[1],1);
85	    }
86	}
87}
88