1 /* e_rem_pio2f.c -- float version of e_rem_pio2.c 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 * Debugged and 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 /* __ieee754_rem_pio2f(x,y) 18 * 19 * return the remainder of x rem pi/2 in *y 20 * use double precision for everything except passing x 21 * use __kernel_rem_pio2() for large x 22 */ 23 24 #include <float.h> 25 26 #include "math.h" 27 #include "math_private.h" 28 29 /* 30 * invpio2: 53 bits of 2/pi 31 * pio2_1: first 25 bits of pi/2 32 * pio2_1t: pi/2 - pio2_1 33 */ 34 35 static const double 36 invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */ 37 pio2_1 = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */ 38 pio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */ 39 40 #ifdef INLINE_REM_PIO2F 41 static __always_inline 42 #endif 43 int 44 __ieee754_rem_pio2f(float x, double *y) 45 { 46 double w,r,fn; 47 double tx[1],ty[1]; 48 float z; 49 int32_t e0,n,ix,hx; 50 51 GET_FLOAT_WORD(hx,x); 52 ix = hx&0x7fffffff; 53 /* 33+53 bit pi is good enough for medium size */ 54 if(ix<0x4dc90fdb) { /* |x| ~< 2^28*(pi/2), medium size */ 55 fn = rnint((float_t)x*invpio2); 56 n = irint(fn); 57 r = x-fn*pio2_1; 58 w = fn*pio2_1t; 59 *y = r-w; 60 return n; 61 } 62 /* 63 * all other (large) arguments 64 */ 65 if(ix>=0x7f800000) { /* x is inf or NaN */ 66 *y=x-x; return 0; 67 } 68 /* set z = scalbn(|x|,ilogb(|x|)-23) */ 69 e0 = (ix>>23)-150; /* e0 = ilogb(|x|)-23; */ 70 SET_FLOAT_WORD(z, ix - ((int32_t)((u_int32_t)e0<<23))); 71 tx[0] = z; 72 n = __kernel_rem_pio2(tx,ty,e0,1,0); 73 if(hx<0) {*y = -ty[0]; return -n;} 74 *y = ty[0]; return n; 75 } 76