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 * ====================================================
13 #include <sys/cdefs.h>
14 __FBSDID("$FreeBSD$");
18 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
25 #include "math_private.h"
28 two54 = 1.80143985094819840000e+16; /* 43500000 00000000 */
34 EXTRACT_WORDS(ix,lx,x);
35 ix &= 0x7fffffff; /* high |x| */
36 if((ix|lx)==0) return -1.0/fabs(x);
37 if(ix>=0x7ff00000) return x*x;
39 x *= two54; /* convert subnormal x to normal */
42 return (double) ((ix>>20)-1023-54);
44 return (double) ((ix>>20)-1023);
47 #if (LDBL_MANT_DIG == 53)
48 __weak_reference(logb, logbl);