1 /* s_rintf.c -- float version of s_rint.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 17 static char rcsid[] = "$FreeBSD$"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 /* 24 * TWO23 is double instead of float to avoid a bug in gcc. Without 25 * this, gcc thinks that TWO23[sx]+x and w-TWO23[sx] already have float 26 * precision and doesn't clip them to float precision when they are 27 * assigned and returned. 28 */ 29 #ifdef __STDC__ 30 static const double 31 #else 32 static double 33 #endif 34 TWO23[2]={ 35 8.3886080000e+06, /* 0x4b000000 */ 36 -8.3886080000e+06, /* 0xcb000000 */ 37 }; 38 39 #ifdef __STDC__ 40 float rintf(float x) 41 #else 42 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