1 /* sf_logb.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 "fdlibm.h" 17 18 #ifdef __STDC__ logbf(float x)19 float logbf(float x) 20 #else 21 float logbf(x) 22 float x; 23 #endif 24 { 25 __int32_t ix; 26 GET_FLOAT_WORD(ix,x); 27 ix &= 0x7fffffff; /* high |x| */ 28 if(FLT_UWORD_IS_ZERO(ix)) return (float)-1.0/fabsf(x); 29 if(!FLT_UWORD_IS_FINITE(ix)) return x*x; 30 if((ix>>=23)==0) /* IEEE 754 logb */ 31 return -126.0; 32 else 33 return (float) (ix-127); 34 } 35 36 #ifdef _DOUBLE_IS_32BITS 37 38 #ifdef __STDC__ logb(double x)39 double logb(double x) 40 #else 41 double logb(x) 42 double x; 43 #endif 44 { 45 return (double) logbf((float) x); 46 } 47 48 #endif /* defined(_DOUBLE_IS_32BITS) */ 49