e_rem_pio2f.c revision 302408
138716Smsmith/* e_rem_pio2f.c -- float version of e_rem_pio2.c 238716Smsmith * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 338716Smsmith * Debugged and optimized by Bruce D. Evans. 438716Smsmith */ 538716Smsmith 638716Smsmith/* 738716Smsmith * ==================================================== 838716Smsmith * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 938716Smsmith * 1038716Smsmith * Developed at SunPro, a Sun Microsystems, Inc. business. 1138716Smsmith * Permission to use, copy, modify, and distribute this 1238716Smsmith * software is freely granted, provided that this notice 1338716Smsmith * is preserved. 1444570Sdcs * ==================================================== 1538716Smsmith */ 1638716Smsmith 1738716Smsmith#include <sys/cdefs.h> 1838716Smsmith__FBSDID("$FreeBSD: stable/11/lib/msun/src/e_rem_pio2f.c 239195 2012-08-11 15:47:22Z dim $"); 1938716Smsmith 2038716Smsmith/* __ieee754_rem_pio2f(x,y) 2138716Smsmith * 2238716Smsmith * return the remainder of x rem pi/2 in *y 2338716Smsmith * use double precision for everything except passing x 2438716Smsmith * use __kernel_rem_pio2() for large x 2538716Smsmith */ 2638716Smsmith 2738716Smsmith#include <float.h> 2838716Smsmith 2938716Smsmith#include "math.h" 3038716Smsmith#include "math_private.h" 3138716Smsmith 3238716Smsmith/* 3338716Smsmith * invpio2: 53 bits of 2/pi 3438716Smsmith * pio2_1: first 25 bits of pi/2 3538716Smsmith * pio2_1t: pi/2 - pio2_1 3638716Smsmith */ 3738716Smsmith 3838716Smsmithstatic const double 3938716Smsmithinvpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */ 4038716Smsmithpio2_1 = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */ 4138716Smsmithpio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */ 4238716Smsmith 4338716Smsmith#ifdef INLINE_REM_PIO2F 4438716Smsmithstatic __inline __always_inline 4538716Smsmith#endif 4638716Smsmithint 4738716Smsmith__ieee754_rem_pio2f(float x, double *y) 4838716Smsmith{ 4938716Smsmith double w,r,fn; 5038716Smsmith double tx[1],ty[1]; 5138716Smsmith float z; 5238716Smsmith int32_t e0,n,ix,hx; 5338716Smsmith 5438716Smsmith GET_FLOAT_WORD(hx,x); 5538716Smsmith ix = hx&0x7fffffff; 5638716Smsmith /* 33+53 bit pi is good enough for medium size */ 5738716Smsmith if(ix<0x4dc90fdb) { /* |x| ~< 2^28*(pi/2), medium size */ 5838716Smsmith /* Use a specialized rint() to get fn. Assume round-to-nearest. */ 5938716Smsmith STRICT_ASSIGN(double,fn,x*invpio2+0x1.8p52); 6038716Smsmith fn = fn-0x1.8p52; 6138716Smsmith#ifdef HAVE_EFFICIENT_IRINT 6238716Smsmith n = irint(fn); 6338716Smsmith#else 6438716Smsmith n = (int32_t)fn; 6538716Smsmith#endif 6638716Smsmith r = x-fn*pio2_1; 6738716Smsmith w = fn*pio2_1t; 6838716Smsmith *y = r-w; 6938716Smsmith return n; 7038716Smsmith } 7138716Smsmith /* 7238716Smsmith * all other (large) arguments 7338765Sjkh */ 7438765Sjkh if(ix>=0x7f800000) { /* x is inf or NaN */ 7538765Sjkh *y=x-x; return 0; 7638765Sjkh } 7738765Sjkh /* set z = scalbn(|x|,ilogb(|x|)-23) */ 7838765Sjkh e0 = (ix>>23)-150; /* e0 = ilogb(|x|)-23; */ 7938716Smsmith SET_FLOAT_WORD(z, ix - ((int32_t)(e0<<23))); 8038716Smsmith tx[0] = z; 8138716Smsmith n = __kernel_rem_pio2(tx,ty,e0,1,0); 8238716Smsmith if(hx<0) {*y = -ty[0]; return -n;} 8338716Smsmith *y = ty[0]; return n; 8438716Smsmith} 8538765Sjkh