1 /* @(#)s_ilogb.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 * ====================================================
14 static char rcsid[] = "$FreeBSD$";
18 * return the binary exponent of non-zero x
19 * ilogb(0) = FP_ILOGB0
20 * ilogb(NaN) = FP_ILOGBNAN (no signal is raised)
21 * ilogb(inf) = INT_MAX (no signal is raised)
27 #include "math_private.h"
33 EXTRACT_WORDS(hx,lx,x);
38 else /* subnormal x */
40 for (ix = -1043; lx>0; lx<<=1) ix -=1;
42 for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1;
46 else if (hx<0x7ff00000) return (hx>>20)-1023;
47 else if (hx>0x7ff00000 || lx!=0) return FP_ILOGBNAN;