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 * ====================================================
12 * $FreeBSD: src/lib/msun/src/s_ilogb.c,v 1.6 1999/08/28 00:06:49 peter Exp $
13 * $DragonFly: src/lib/msun/src/Attic/s_ilogb.c,v 1.2 2003/06/17 04:26:53 dillon Exp $
17 * return the binary exponent of non-zero x
18 * ilogb(0) = 0x80000001
19 * ilogb(inf/NaN) = 0x7fffffff (no signal is raised)
23 #include "math_private.h"
26 int __generic_ilogb(double x)
28 int __generic_ilogb(x)
34 EXTRACT_WORDS(hx,lx,x);
38 return 0x80000001; /* ilogb(0) = 0x80000001 */
39 else /* subnormal x */
41 for (ix = -1043; lx>0; lx<<=1) ix -=1;
43 for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1;
47 else if (hx<0x7ff00000) return (hx>>20)-1023;
48 else return 0x7fffffff;