1 /* @(#)s_logb.c 5.1 93/09/24 */
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
10 * ====================================================
15 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
20 #include "math_private.h"
26 EXTRACT_WORDS(ix,lx,x);
27 ix &= 0x7fffffff; /* high |x| */
28 if((ix|lx)==0) return -1.0/fabs(x);
29 if(ix>=0x7ff00000) return x*x;
30 if((ix>>=20)==0) /* IEEE 754 logb */
33 return (double) (ix-1023);