s_ilogbf.c revision 8870 
1/* s_ilogbf.c -- float version of s_ilogb.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#ifndef lint
17static char rcsid[] = "$Id: s_ilogbf.c,v 1.1.1.1 1994/08/19 09:39:58 jkh Exp $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23#ifdef __STDC__
24	int ilogbf(float x)
25#else
26	int ilogbf(x)
27	float x;
28#endif
29{
30	int32_t hx,ix;
31
32	GET_FLOAT_WORD(hx,x);
33	hx &= 0x7fffffff;
34	if(hx<0x00800000) {
35	    if(hx==0)
36		return 0x80000001;	/* ilogb(0) = 0x80000001 */
37	    else			/* subnormal x */
38	        for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
39	    return ix;
40	}
41	else if (hx<0x7f800000) return (hx>>23)-127;
42	else return 0x7fffffff;
43}
44