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. */ 20 static const double 21 c1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ 22 c2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ 23 c3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ 24 c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ 25 26 float cosf(float x) 27 { 28 double y; 29 uint32_t ix; 30 unsigned 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 */ 39 FORCE_EVAL(x + 0x1p120f); 40 return 1.0f; 41 } 42 return __cosdf(x); 43 } 44 if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */ 45 if (ix > 0x4016cbe3) /* |x| ~> 3*pi/4 */ 46 return -__cosdf(sign ? x+c2pio2 : x-c2pio2); 47 else { 48 if (sign) 49 return __sindf(x + c1pio2); 50 else 51 return __sindf(c1pio2 - x); 52 } 53 } 54 if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */ 55 if (ix > 0x40afeddf) /* |x| ~> 7*pi/4 */ 56 return __cosdf(sign ? x+c4pio2 : x-c4pio2); 57 else { 58 if (sign) 59 return __sindf(-x - c3pio2); 60 else 61 return __sindf(x - c3pio2); 62 } 63 } 64 65 /* cos(Inf or NaN) is NaN */ 66 if (ix >= 0x7f800000) 67 return x-x; 68 69 /* general argument reduction needed */ 70 n = __rem_pio2f(x,&y); 71 switch (n&3) { 72 case 0: return __cosdf(y); 73 case 1: return __sindf(-y); 74 case 2: return -__cosdf(y); 75 default: 76 return __sindf(y); 77 } 78 } 79