1/* origin: FreeBSD /usr/src/lib/msun/src/s_cosf.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. */ 20static const double c1pio2 = 1 * M_PI_2, /* 0x3FF921FB, 0x54442D18 */ 21 c2pio2 = 2 * M_PI_2, /* 0x400921FB, 0x54442D18 */ 22 c3pio2 = 3 * M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ 23 c4pio2 = 4 * M_PI_2; /* 0x401921FB, 0x54442D18 */ 24 25float cosf(float x) { 26 double y; 27 uint32_t ix; 28 unsigned n, sign; 29 30 GET_FLOAT_WORD(ix, x); 31 sign = ix >> 31; 32 ix &= 0x7fffffff; 33 34 if (ix <= 0x3f490fda) { /* |x| ~<= pi/4 */ 35 if (ix < 0x39800000) { /* |x| < 2**-12 */ 36 /* raise inexact if x != 0 */ 37 FORCE_EVAL(x + 0x1p120f); 38 return 1.0f; 39 } 40 return __cosdf(x); 41 } 42 if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */ 43 if (ix > 0x4016cbe3) /* |x| ~> 3*pi/4 */ 44 return -__cosdf(sign ? x + c2pio2 : x - c2pio2); 45 else { 46 if (sign) 47 return __sindf(x + c1pio2); 48 else 49 return __sindf(c1pio2 - x); 50 } 51 } 52 if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */ 53 if (ix > 0x40afeddf) /* |x| ~> 7*pi/4 */ 54 return __cosdf(sign ? x + c4pio2 : x - c4pio2); 55 else { 56 if (sign) 57 return __sindf(-x - c3pio2); 58 else 59 return __sindf(x - c3pio2); 60 } 61 } 62 63 /* cos(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: 71 return __cosdf(y); 72 case 1: 73 return __sindf(-y); 74 case 2: 75 return -__cosdf(y); 76 default: 77 return __sindf(y); 78 } 79} 80