| /* @(#)s_logb.c 5.1 93/09/24 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| #if defined(LIBM_SCCS) && !defined(lint) |
| static char rcsid[] = "$NetBSD: s_logb.c,v 1.8 1995/05/10 20:47:50 jtc Exp $"; |
| #endif |
| |
| /* |
| * double logb(x) |
| * IEEE 754 logb. Included to pass IEEE test suite. Not recommend. |
| * Use ilogb instead. |
| */ |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| #ifdef __STDC__ |
| double __logb(double x) |
| #else |
| double __logb(x) |
| double x; |
| #endif |
| { |
| int32_t lx,ix; |
| EXTRACT_WORDS(ix,lx,x); |
| ix &= 0x7fffffff; /* high |x| */ |
| if((ix|lx)==0) return -1.0/fabs(x); |
| if(ix>=0x7ff00000) return x*x; |
| if((ix>>=20)==0) /* IEEE 754 logb */ |
| return -1022.0; |
| else |
| return (double) (ix-1023); |
| } |
| weak_alias (__logb, logb) |
| #ifdef NO_LONG_DOUBLE |
| strong_alias (__logb, __logbl) |
| weak_alias (__logb, logbl) |
| #endif |
