xref: /freebsd/lib/msun/src/s_cosf.c (revision 525fe93dc7487a1e63a90f6a2b956abc601963c1)
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 #include <float.h>
19 
20 #include "math.h"
21 #define	INLINE_KERNEL_COSDF
22 #define	INLINE_KERNEL_SINDF
23 #define INLINE_REM_PIO2F
24 #include "math_private.h"
25 #include "e_rem_pio2f.c"
26 #include "k_cosf.c"
27 #include "k_sinf.c"
28 
29 /* Small multiples of pi/2 rounded to double precision. */
30 static const double
31 c1pio2 = 1*M_PI_2,			/* 0x3FF921FB, 0x54442D18 */
32 c2pio2 = 2*M_PI_2,			/* 0x400921FB, 0x54442D18 */
33 c3pio2 = 3*M_PI_2,			/* 0x4012D97C, 0x7F3321D2 */
34 c4pio2 = 4*M_PI_2;			/* 0x401921FB, 0x54442D18 */
35 
36 float
37 cosf(float x)
38 {
39 	double y;
40 	int32_t n, hx, ix;
41 
42 	GET_FLOAT_WORD(hx,x);
43 	ix = hx & 0x7fffffff;
44 
45 	if(ix <= 0x3f490fda) {		/* |x| ~<= pi/4 */
46 	    if(ix<0x39800000)		/* |x| < 2**-12 */
47 		if(((int)x)==0) return 1.0;	/* 1 with inexact if x != 0 */
48 	    return __kernel_cosdf(x);
49 	}
50 	if(ix<=0x407b53d1) {		/* |x| ~<= 5*pi/4 */
51 	    if(ix>0x4016cbe3)		/* |x|  ~> 3*pi/4 */
52 		return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2));
53 	    else {
54 		if(hx>0)
55 		    return __kernel_sindf(c1pio2 - x);
56 		else
57 		    return __kernel_sindf(x + c1pio2);
58 	    }
59 	}
60 	if(ix<=0x40e231d5) {		/* |x| ~<= 9*pi/4 */
61 	    if(ix>0x40afeddf)		/* |x|  ~> 7*pi/4 */
62 		return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2));
63 	    else {
64 		if(hx>0)
65 		    return __kernel_sindf(x - c3pio2);
66 		else
67 		    return __kernel_sindf(-c3pio2 - x);
68 	    }
69 	}
70 
71     /* cos(Inf or NaN) is NaN */
72 	else if (ix>=0x7f800000) return x-x;
73 
74     /* general argument reduction needed */
75 	else {
76 	    n = __ieee754_rem_pio2f(x,&y);
77 	    switch(n&3) {
78 		case 0: return  __kernel_cosdf(y);
79 		case 1: return  __kernel_sindf(-y);
80 		case 2: return -__kernel_cosdf(y);
81 		default:
82 		        return  __kernel_sindf(y);
83 	    }
84 	}
85 }
86