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 #include "math.h" 17 #include "math_private.h" 18 19 static const float 20 TWO23[2]={ 21 8.3886080000e+06, /* 0x4b000000 */ 22 -8.3886080000e+06, /* 0xcb000000 */ 23 }; 24 25 float 26 rintf(float x) 27 { 28 int32_t i0,jj0,sx; 29 u_int32_t i,i1; 30 float t; 31 volatile float w; /* clip extra precision */ 32 GET_FLOAT_WORD(i0,x); 33 sx = (i0>>31)&1; 34 jj0 = ((i0>>23)&0xff)-0x7f; 35 if(jj0<23) { 36 if(jj0<0) { 37 if((i0&0x7fffffff)==0) return x; 38 i1 = (i0&0x07fffff); 39 i0 &= 0xfff00000; 40 i0 |= ((i1|-i1)>>9)&0x400000; 41 SET_FLOAT_WORD(x,i0); 42 w = TWO23[sx]+x; 43 t = w-TWO23[sx]; 44 GET_FLOAT_WORD(i0,t); 45 SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31)); 46 return t; 47 } else { 48 i = (0x007fffff)>>jj0; 49 if((i0&i)==0) return x; /* x is integral */ 50 i>>=1; 51 if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>jj0); 52 } 53 } else { 54 if(jj0==0x80) return x+x; /* inf or NaN */ 55 else return x; /* x is integral */ 56 } 57 SET_FLOAT_WORD(x,i0); 58 w = TWO23[sx]+x; 59 return w-TWO23[sx]; 60 } 61