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 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