s_cosf.c revision 97413 
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 97413 2002-05-28 18:15:04Z alfred $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23static const float one=1.0;
24
25float
26cosf(float x)
27{
28	float y[2],z=0.0;
29	int32_t n,ix;
30
31	GET_FLOAT_WORD(ix,x);
32
33    /* |x| ~< pi/4 */
34	ix &= 0x7fffffff;
35	if(ix <= 0x3f490fd8) return __kernel_cosf(x,z);
36
37    /* cos(Inf or NaN) is NaN */
38	else if (ix>=0x7f800000) return x-x;
39
40    /* argument reduction needed */
41	else {
42	    n = __ieee754_rem_pio2f(x,y);
43	    switch(n&3) {
44		case 0: return  __kernel_cosf(y[0],y[1]);
45		case 1: return -__kernel_sinf(y[0],y[1],1);
46		case 2: return -__kernel_cosf(y[0],y[1]);
47		default:
48		        return  __kernel_sinf(y[0],y[1],1);
49	    }
50	}
51}
52