s_cosf.c revision a27d2baa0c1a2ec70f47ea9199b1dd6762c8a349 
1/* s_cosf.c -- float version of s_cos.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 * Optimized by Bruce D. Evans.
4 */
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#ifndef lint
18static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_cosf.c,v 1.15 2005/11/30 06:47:18 bde Exp $";
19#endif
20
21#include "math.h"
22#define	INLINE_KERNEL_COSDF
23#define	INLINE_KERNEL_SINDF
24#include "math_private.h"
25#include "k_cosf.c"
26#include "k_sinf.c"
27
28/* Small multiples of pi/2 rounded to double precision. */
29static const double
30c1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
31c2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
32c3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
33c4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
34
35float
36cosf(float x)
37{
38	float y[2];
39	int32_t n, hx, ix;
40
41	GET_FLOAT_WORD(hx,x);
42	ix = hx & 0x7fffffff;
43
44	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
45	    if(ix<0x39800000)		/* |x| < 2**-12 */
46		if(((int)x)==0) return 1.0;	/* 1 with inexact if x != 0 */
47	    return __kernel_cosdf(x);
48	}
49	if(ix<=0x407b53d1) {		/* |x| ~<= 5*pi/4 */
50	    if(ix>0x4016cbe3)		/* |x|  ~> 3*pi/4 */
51		return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2));
52	    else {
53		if(hx>0)
54		    return __kernel_sindf(c1pio2 - x);
55		else
56		    return __kernel_sindf(x + c1pio2);
57	    }
58	}
59	if(ix<=0x40e231d5) {		/* |x| ~<= 9*pi/4 */
60	    if(ix>0x40afeddf)		/* |x|  ~> 7*pi/4 */
61		return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2));
62	    else {
63		if(hx>0)
64		    return __kernel_sindf(x - c3pio2);
65		else
66		    return __kernel_sindf(-c3pio2 - x);
67	    }
68	}
69
70    /* cos(Inf or NaN) is NaN */
71	else if (ix>=0x7f800000) return x-x;
72
73    /* general argument reduction needed */
74	else {
75	    n = __ieee754_rem_pio2f(x,y);
76	    switch(n&3) {
77		case 0: return  __kernel_cosdf((double)y[0]+y[1]);
78		case 1: return  __kernel_sindf(-(double)y[0]-y[1]);
79		case 2: return -__kernel_cosdf((double)y[0]+y[1]);
80		default:
81		        return  __kernel_sindf((double)y[0]+y[1]);
82	    }
83	}
84}
85