s_tanf.c revision 176552 
1/* s_tanf.c -- float version of s_tan.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_tanf.c 176552 2008-02-25 13:33:20Z bde $");
19
20#include "math.h"
21#define	INLINE_KERNEL_TANDF
22#include "math_private.h"
23#include "k_tanf.c"
24
25/* Small multiples of pi/2 rounded to double precision. */
26static const double
27t1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
28t2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
29t3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
30t4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
31
32float
33tanf(float x)
34{
35	double y;
36	int32_t n, hx, ix;
37
38	GET_FLOAT_WORD(hx,x);
39	ix = hx & 0x7fffffff;
40
41	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
42	    if(ix<0x39800000)		/* |x| < 2**-12 */
43		if(((int)x)==0) return x;	/* x with inexact if x != 0 */
44	    return __kernel_tandf(x,1);
45	}
46	if(ix<=0x407b53d1) {		/* |x| ~<= 5*pi/4 */
47	    if(ix<=0x4016cbe3)		/* |x| ~<= 3pi/4 */
48		return __kernel_tandf(x + (hx>0 ? -t1pio2 : t1pio2), -1);
49	    else
50		return __kernel_tandf(x + (hx>0 ? -t2pio2 : t2pio2), 1);
51	}
52	if(ix<=0x40e231d5) {		/* |x| ~<= 9*pi/4 */
53	    if(ix<=0x40afeddf)		/* |x| ~<= 7*pi/4 */
54		return __kernel_tandf(x + (hx>0 ? -t3pio2 : t3pio2), -1);
55	    else
56		return __kernel_tandf(x + (hx>0 ? -t4pio2 : t4pio2), 1);
57	}
58
59    /* tan(Inf or NaN) is NaN */
60	else if (ix>=0x7f800000) return x-x;
61
62    /* general argument reduction needed */
63	else {
64	    n = __ieee754_rem_pio2f(x,&y);
65	    /* integer parameter: 1 -- n even; -1 -- n odd */
66	    return __kernel_tandf(y,1-((n&1)<<1));
67	}
68}
69