s_cosf.c revision 176552 
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: head/lib/msun/src/s_cosf.c 176552 2008-02-25 13:33:20Z bde $");
19
20#include "math.h"
21#define	INLINE_KERNEL_COSDF
22#define	INLINE_KERNEL_SINDF
23#include "math_private.h"
24#include "k_cosf.c"
25#include "k_sinf.c"
26
27/* Small multiples of pi/2 rounded to double precision. */
28static const double
29c1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
30c2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
31c3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
32c4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
33
34float
35cosf(float x)
36{
37	double y;
38	int32_t n, hx, ix;
39
40	GET_FLOAT_WORD(hx,x);
41	ix = hx & 0x7fffffff;
42
43	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
44	    if(ix<0x39800000)		/* |x| < 2**-12 */
45		if(((int)x)==0) return 1.0;	/* 1 with inexact if x != 0 */
46	    return __kernel_cosdf(x);
47	}
48	if(ix<=0x407b53d1) {		/* |x| ~<= 5*pi/4 */
49	    if(ix>0x4016cbe3)		/* |x|  ~> 3*pi/4 */
50		return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2));
51	    else {
52		if(hx>0)
53		    return __kernel_sindf(c1pio2 - x);
54		else
55		    return __kernel_sindf(x + c1pio2);
56	    }
57	}
58	if(ix<=0x40e231d5) {		/* |x| ~<= 9*pi/4 */
59	    if(ix>0x40afeddf)		/* |x|  ~> 7*pi/4 */
60		return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2));
61	    else {
62		if(hx>0)
63		    return __kernel_sindf(x - c3pio2);
64		else
65		    return __kernel_sindf(-c3pio2 - x);
66	    }
67	}
68
69    /* cos(Inf or NaN) is NaN */
70	else if (ix>=0x7f800000) return x-x;
71
72    /* general argument reduction needed */
73	else {
74	    n = __ieee754_rem_pio2f(x,&y);
75	    switch(n&3) {
76		case 0: return  __kernel_cosdf(y);
77		case 1: return  __kernel_sindf(-y);
78		case 2: return -__kernel_cosdf(y);
79		default:
80		        return  __kernel_sindf(y);
81	    }
82	}
83}
84