s_sinf.c revision 152596
1/* s_sinf.c -- float version of s_sin.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5/* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16#ifndef lint 17static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_sinf.c 152596 2005-11-19 02:38:27Z bde $"; 18#endif 19 20#include "math.h" 21#include "math_private.h" 22 23/* Small multiples of pi/2 rounded to double precision. */ 24static const double 25s1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ 26s2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ 27s3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ 28s4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ 29 30static inline float 31__kernel_cosdf(double x) 32{ 33 return __kernel_cosf((float)x, x - (float)x); 34} 35 36static inline float 37__kernel_sindf(double x) 38{ 39 return __kernel_sinf((float)x, x - (float)x, 1); 40} 41 42float 43sinf(float x) 44{ 45 float y[2]; 46 int32_t n, hx, ix; 47 48 GET_FLOAT_WORD(hx,x); 49 ix = hx & 0x7fffffff; 50 51 if(ix <= 0x3f490fda) { /* |x| ~<= pi/4 */ 52 if(ix<0x39800000) /* |x| < 2**-12 */ 53 if(((int)x)==0) return x; /* x with inexact if x != 0 */ 54 return __kernel_sinf(x,0.0,0); 55 } 56 if(ix<=0x407b53d1) { /* |x| <= ~5*pi/4 */ 57 if(ix<=0x4016cbe3) { /* |x| <= ~3pi/4 */ 58 if(hx>0) 59 return __kernel_cosdf(x - s1pio2); 60 else 61 return -__kernel_cosdf(x + s1pio2); 62 } else 63 return -__kernel_sindf(x + (hx > 0 ? -s2pio2 : s2pio2)); 64 } 65 if(ix<=0x40e231d5) { /* |x| <= ~9*pi/4 */ 66 if(ix<=0x40afeddf) { /* |x| <= ~7*pi/4 */ 67 if(hx>0) 68 return -__kernel_cosdf(x - s3pio2); 69 else 70 return __kernel_cosdf(x + s3pio2); 71 } else 72 return __kernel_sindf(x + (hx > 0 ? -s4pio2 : s4pio2)); 73 } 74 75 /* sin(Inf or NaN) is NaN */ 76 else if (ix>=0x7f800000) return x-x; 77 78 /* general argument reduction needed */ 79 else { 80 n = __ieee754_rem_pio2f(x,y); 81 switch(n&3) { 82 case 0: return __kernel_sinf(y[0],y[1],1); 83 case 1: return __kernel_cosf(y[0],y[1]); 84 case 2: return -__kernel_sinf(y[0],y[1],1); 85 default: 86 return -__kernel_cosf(y[0],y[1]); 87 } 88 } 89} 90