s_logbf.c revision 153049
1/* s_logbf.c -- float version of s_logb.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 17static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_logbf.c 153049 2005-12-03 11:57:19Z bde $"; 18#endif 19 20#include "math.h" 21#include "math_private.h" 22 23static const float 24two25 = 3.355443200e+07; /* 0x4c000000 */ 25 26float 27logbf(float x) 28{ 29 int32_t ix; 30 GET_FLOAT_WORD(ix,x); 31 ix &= 0x7fffffff; /* high |x| */ 32 if(ix==0) return (float)-1.0/fabsf(x); 33 if(ix>=0x7f800000) return x*x; 34 if(ix<0x00800000) { 35 x *= two25; /* convert subnormal x to normal */ 36 GET_FLOAT_WORD(ix,x); 37 ix &= 0x7fffffff; 38 return (float) ((ix>>23)-127-25); 39 } else 40 return (float) ((ix>>23)-127); 41} 42