1 /* @(#)s_ilogb.c 5.1 93/09/24 */
2 /* $FreeBSD: head/lib/msun/src/s_ilogb.c 176451 2008-02-22 02:30:36Z das $ */
4 * ====================================================
5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 * Developed at SunPro, a Sun Microsystems, Inc. business.
8 * Permission to use, copy, modify, and distribute this
9 * software is freely granted, provided that this notice
11 * ====================================================
15 * return the binary exponent of non-zero x
16 * ilogb(0) = FP_ILOGB0
17 * ilogb(NaN) = FP_ILOGBNAN (no signal is raised)
18 * ilogb(inf) = INT_MAX (no signal is raised)
24 #include "math_private.h"
30 EXTRACT_WORDS(hx,lx,x);
35 else /* subnormal x */
37 for (ix = -1043; lx>0; lx<<=1) ix -=1;
39 for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1;
43 else if (hx<0x7ff00000) return (hx>>20)-1023;
44 else if (hx>0x7ff00000 || lx!=0) return FP_ILOGBNAN;