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 #include <sys/cdefs.h> 17 #include "math.h" 18 #include "math_private.h" 19 20 static const float 21 two25 = 3.355443200e+07; /* 0x4c000000 */ 22 23 float 24 logbf(float x) 25 { 26 int32_t ix; 27 GET_FLOAT_WORD(ix,x); 28 ix &= 0x7fffffff; /* high |x| */ 29 if(ix==0) return (float)-1.0/fabsf(x); 30 if(ix>=0x7f800000) return x*x; 31 if(ix<0x00800000) { 32 x *= two25; /* convert subnormal x to normal */ 33 GET_FLOAT_WORD(ix,x); 34 ix &= 0x7fffffff; 35 return (float) ((ix>>23)-127-25); 36 } else 37 return (float) ((ix>>23)-127); 38 } 39