s_cosf.c revision 151620 
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 151620 2005-10-24 14:08:36Z bde $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23float
24cosf(float x)
25{
26	float y[2],z=0.0;
27	int32_t n,ix;
28
29	GET_FLOAT_WORD(ix,x);
30
31    /* |x| ~< pi/4 */
32	ix &= 0x7fffffff;
33	if(ix <= 0x3f490fd8) {
34	    if(ix<0x39800000)			/* if x < 2**-12 */
35		if(((int)x)==0) return 1.0;	/* generate inexact */
36	    return __kernel_cosf(x,z);
37	}
38
39    /* cos(Inf or NaN) is NaN */
40	else if (ix>=0x7f800000) return x-x;
41
42    /* argument reduction needed */
43	else {
44	    n = __ieee754_rem_pio2f(x,y);
45	    switch(n&3) {
46		case 0: return  __kernel_cosf(y[0],y[1]);
47		case 1: return -__kernel_sinf(y[0],y[1],1);
48		case 2: return -__kernel_cosf(y[0],y[1]);
49		default:
50		        return  __kernel_sinf(y[0],y[1],1);
51	    }
52	}
53}
54