1 /* origin: FreeBSD /usr/src/lib/msun/src/s_sinf.c */
2 /*
3 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
4 * Optimized by Bruce D. Evans.
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 "libm.h"
18
19 /* Small multiples of pi/2 rounded to double precision. */
20 static const double
21 s1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
22 s2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
23 s3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
24 s4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
25
sinf(float x)26 float sinf(float x)
27 {
28 double y;
29 uint32_t ix;
30 int n, sign;
31
32 GET_FLOAT_WORD(ix, x);
33 sign = ix >> 31;
34 ix &= 0x7fffffff;
35
36 if (ix <= 0x3f490fda) { /* |x| ~<= pi/4 */
37 if (ix < 0x39800000) { /* |x| < 2**-12 */
38 /* raise inexact if x!=0 and underflow if subnormal */
39 FORCE_EVAL(ix < 0x00800000 ? x/0x1p120f : x+0x1p120f);
40 return x;
41 }
42 return __sindf(x);
43 }
44 if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */
45 if (ix <= 0x4016cbe3) { /* |x| ~<= 3pi/4 */
46 if (sign)
47 return -__cosdf(x + s1pio2);
48 else
49 return __cosdf(x - s1pio2);
50 }
51 return __sindf(sign ? -(x + s2pio2) : -(x - s2pio2));
52 }
53 if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */
54 if (ix <= 0x40afeddf) { /* |x| ~<= 7*pi/4 */
55 if (sign)
56 return __cosdf(x + s3pio2);
57 else
58 return -__cosdf(x - s3pio2);
59 }
60 return __sindf(sign ? x + s4pio2 : x - s4pio2);
61 }
62
63 /* sin(Inf or NaN) is NaN */
64 if (ix >= 0x7f800000)
65 return x - x;
66
67 /* general argument reduction needed */
68 n = __rem_pio2f(x, &y);
69 switch (n&3) {
70 case 0: return __sindf(y);
71 case 1: return __cosdf(y);
72 case 2: return __sindf(-y);
73 default:
74 return -__cosdf(y);
75 }
76 }
77