1 /* s_logbf.c -- float version of s_logb.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian (at) 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: src/lib/msun/src/s_logbf.c,v 1.8 2005/12/03 11:57:19 bde Exp $"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 static const float 24 two25 = 3.355443200e+07; /* 0x4c000000 */ 25 26 float 27 logbf(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
