s_rintf.c revision 22993
158551Skris/* s_rintf.c -- float version of s_rint.c. 258551Skris * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 358551Skris */ 458551Skris 558551Skris/* 658551Skris * ==================================================== 758551Skris * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 858551Skris * 958551Skris * Developed at SunPro, a Sun Microsystems, Inc. business. 1058551Skris * Permission to use, copy, modify, and distribute this 1158551Skris * software is freely granted, provided that this notice 1258551Skris * is preserved. 1358551Skris * ==================================================== 1458551Skris */ 1558551Skris 1658551Skris#ifndef lint 1758551Skrisstatic char rcsid[] = "$Id$"; 1858551Skris#endif 1958551Skris 2058551Skris#include "math.h" 2158551Skris#include "math_private.h" 2258551Skris 2358551Skris/* 2458551Skris * TWO23 is double instead of float to avoid a bug in gcc. Without 2558551Skris * this, gcc thinks that TWO23[sx]+x and w-TWO23[sx] already have float 2658551Skris * precision and doesn't clip them to float precision when they are 2758551Skris * assigned and returned. 2858551Skris */ 2958551Skris#ifdef __STDC__ 3058551Skrisstatic const double 3158551Skris#else 3258551Skrisstatic double 3358551Skris#endif 3458551SkrisTWO23[2]={ 3558551Skris 8.3886080000e+06, /* 0x4b000000 */ 3658551Skris -8.3886080000e+06, /* 0xcb000000 */ 3758551Skris}; 3858551Skris 3958551Skris#ifdef __STDC__ 4058551Skris float rintf(float x) 4158551Skris#else 4258551Skris float rintf(x) 43 float x; 44#endif 45{ 46 int32_t i0,j0,sx; 47 u_int32_t i,i1; 48 float w,t; 49 GET_FLOAT_WORD(i0,x); 50 sx = (i0>>31)&1; 51 j0 = ((i0>>23)&0xff)-0x7f; 52 if(j0<23) { 53 if(j0<0) { 54 if((i0&0x7fffffff)==0) return x; 55 i1 = (i0&0x07fffff); 56 i0 &= 0xfff00000; 57 i0 |= ((i1|-i1)>>9)&0x400000; 58 SET_FLOAT_WORD(x,i0); 59 w = TWO23[sx]+x; 60 t = w-TWO23[sx]; 61 GET_FLOAT_WORD(i0,t); 62 SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31)); 63 return t; 64 } else { 65 i = (0x007fffff)>>j0; 66 if((i0&i)==0) return x; /* x is integral */ 67 i>>=1; 68 if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>j0); 69 } 70 } else { 71 if(j0==0x80) return x+x; /* inf or NaN */ 72 else return x; /* x is integral */ 73 } 74 SET_FLOAT_WORD(x,i0); 75 w = TWO23[sx]+x; 76 return w-TWO23[sx]; 77} 78