s_sinf.c revision 152596 
1/* s_sinf.c -- float version of s_sin.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_sinf.c 152596 2005-11-19 02:38:27Z bde $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23/* Small multiples of pi/2 rounded to double precision. */
24static const double
25s1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
26s2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
27s3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
28s4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
29
30static inline float
31__kernel_cosdf(double x)
32{
33	return __kernel_cosf((float)x, x - (float)x);
34}
35
36static inline float
37__kernel_sindf(double x)
38{
39	return __kernel_sinf((float)x, x - (float)x, 1);
40}
41
42float
43sinf(float x)
44{
45	float y[2];
46	int32_t n, hx, ix;
47
48	GET_FLOAT_WORD(hx,x);
49	ix = hx & 0x7fffffff;
50
51	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
52	    if(ix<0x39800000)		/* |x| < 2**-12 */
53		if(((int)x)==0) return x;	/* x with inexact if x != 0 */
54	    return __kernel_sinf(x,0.0,0);
55	}
56	if(ix<=0x407b53d1) {		/* |x| <= ~5*pi/4 */
57	    if(ix<=0x4016cbe3) {	/* |x| <= ~3pi/4 */
58		if(hx>0)
59		    return __kernel_cosdf(x - s1pio2);
60		else
61		    return -__kernel_cosdf(x + s1pio2);
62	    } else
63		return -__kernel_sindf(x + (hx > 0 ? -s2pio2 : s2pio2));
64	}
65	if(ix<=0x40e231d5) {		/* |x| <= ~9*pi/4 */
66	    if(ix<=0x40afeddf) {	/* |x| <= ~7*pi/4 */
67		if(hx>0)
68		    return -__kernel_cosdf(x - s3pio2);
69		else
70		    return __kernel_cosdf(x + s3pio2);
71	    } else
72		return __kernel_sindf(x + (hx > 0 ? -s4pio2 : s4pio2));
73	}
74
75    /* sin(Inf or NaN) is NaN */
76	else if (ix>=0x7f800000) return x-x;
77
78    /* general argument reduction needed */
79	else {
80	    n = __ieee754_rem_pio2f(x,y);
81	    switch(n&3) {
82		case 0: return  __kernel_sinf(y[0],y[1],1);
83		case 1: return  __kernel_cosf(y[0],y[1]);
84		case 2: return -__kernel_sinf(y[0],y[1],1);
85		default:
86			return -__kernel_cosf(y[0],y[1]);
87	    }
88	}
89}
90