s_cosf.c revision 302408 
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#include <sys/cdefs.h>
18__FBSDID("$FreeBSD: stable/11/lib/msun/src/s_cosf.c 176569 2008-02-25 22:19:17Z bde $");
19
20#include <float.h>
21
22#include "math.h"
23#define	INLINE_KERNEL_COSDF
24#define	INLINE_KERNEL_SINDF
25#define INLINE_REM_PIO2F
26#include "math_private.h"
27#include "e_rem_pio2f.c"
28#include "k_cosf.c"
29#include "k_sinf.c"
30
31/* Small multiples of pi/2 rounded to double precision. */
32static const double
33c1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
34c2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
35c3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
36c4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
37
38float
39cosf(float x)
40{
41	double y;
42	int32_t n, hx, ix;
43
44	GET_FLOAT_WORD(hx,x);
45	ix = hx & 0x7fffffff;
46
47	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
48	    if(ix<0x39800000)		/* |x| < 2**-12 */
49		if(((int)x)==0) return 1.0;	/* 1 with inexact if x != 0 */
50	    return __kernel_cosdf(x);
51	}
52	if(ix<=0x407b53d1) {		/* |x| ~<= 5*pi/4 */
53	    if(ix>0x4016cbe3)		/* |x|  ~> 3*pi/4 */
54		return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2));
55	    else {
56		if(hx>0)
57		    return __kernel_sindf(c1pio2 - x);
58		else
59		    return __kernel_sindf(x + c1pio2);
60	    }
61	}
62	if(ix<=0x40e231d5) {		/* |x| ~<= 9*pi/4 */
63	    if(ix>0x40afeddf)		/* |x|  ~> 7*pi/4 */
64		return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2));
65	    else {
66		if(hx>0)
67		    return __kernel_sindf(x - c3pio2);
68		else
69		    return __kernel_sindf(-c3pio2 - x);
70	    }
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_cosdf(y);
81		case 1: return  __kernel_sindf(-y);
82		case 2: return -__kernel_cosdf(y);
83		default:
84		        return  __kernel_sindf(y);
85	    }
86	}
87}
88