s_cosf.c revision 152872
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#ifndef lint 18static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_cosf.c 152872 2005-11-28 06:15:10Z bde $"; 19#endif 20 21#include "math.h" 22#define INLINE_KERNEL_COSDF 23#define INLINE_KERNEL_SINDF 24#include "math_private.h" 25#include "k_cosf.c" 26#include "k_sinf.c" 27 28/* Small multiples of pi/2 rounded to double precision. */ 29static const double 30c1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ 31c2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ 32c3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ 33c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ 34 35float 36cosf(float x) 37{ 38 float y[2]; 39 int32_t n,ix; 40 41 x = fabsf(x); 42 GET_FLOAT_WORD(ix,x); 43 44 if(ix <= 0x3f490fda) { /* |x| ~<= pi/4 */ 45 if(ix<0x39800000) /* |x| < 2**-12 */ 46 if(((int)x)==0) return 1.0; /* 1 with inexact if x != 0 */ 47 return __kernel_cosdf(x); 48 } 49 if(ix<=0x407b53d1) { /* |x| ~<= 5*pi/4 */ 50 if(ix<=0x4016cbe3) /* |x| ~<= 3pi/4 */ 51 return __kernel_sindf(c1pio2 - x); 52 else 53 return -__kernel_cosdf(x - c2pio2); 54 } 55 if(ix<=0x40e231d5) { /* |x| ~<= 9*pi/4 */ 56 if(ix<=0x40afeddf) /* |x| ~<= 7*pi/4 */ 57 return __kernel_sindf(x - c3pio2); 58 else 59 return __kernel_cosdf(x - c4pio2); 60 } 61 62 /* cos(Inf or NaN) is NaN */ 63 else if (ix>=0x7f800000) return x-x; 64 65 /* general argument reduction needed */ 66 else { 67 n = __ieee754_rem_pio2f(x,y); 68 switch(n&3) { 69 case 0: return __kernel_cosdf((double)y[0]+y[1]); 70 case 1: return __kernel_sindf(-(double)y[0]-y[1]); 71 case 2: return -__kernel_cosdf((double)y[0]+y[1]); 72 default: 73 return __kernel_sindf((double)y[0]+y[1]); 74 } 75 } 76} 77