s_cosf.c revision 152540 
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 152540 2005-11-17 03:53:22Z bde $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23float
24cosf(float x)
25{
26	float y[2];
27	int32_t n,ix;
28
29	GET_FLOAT_WORD(ix,x);
30	ix &= 0x7fffffff;
31
32	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
33	    if(ix<0x39800000)		/* |x| < 2**-12 */
34		if(((int)x)==0) return 1.0;	/* 1 with inexact if x != 0 */
35	    return __kernel_cosf(x,0.0);
36	}
37
38    /* cos(Inf or NaN) is NaN */
39	else if (ix>=0x7f800000) return x-x;
40
41    /* argument reduction needed */
42	else {
43	    n = __ieee754_rem_pio2f(x,y);
44	    switch(n&3) {
45		case 0: return  __kernel_cosf(y[0],y[1]);
46		case 1: return -__kernel_sinf(y[0],y[1],1);
47		case 2: return -__kernel_cosf(y[0],y[1]);
48		default:
49		        return  __kernel_sinf(y[0],y[1],1);
50	    }
51	}
52}
53