s_ilogbf.c revision 2116 
12116Sjkh/* s_ilogbf.c -- float version of s_ilogb.c.
22116Sjkh * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
32116Sjkh */
42116Sjkh
52116Sjkh/*
62116Sjkh * ====================================================
72116Sjkh * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
82116Sjkh *
92116Sjkh * Developed at SunPro, a Sun Microsystems, Inc. business.
102116Sjkh * Permission to use, copy, modify, and distribute this
112116Sjkh * software is freely granted, provided that this notice
122116Sjkh * is preserved.
132116Sjkh * ====================================================
142116Sjkh */
152116Sjkh
162116Sjkh#ifndef lint
172116Sjkhstatic char rcsid[] = "$Id: s_ilogbf.c,v 1.2 1994/08/18 23:06:53 jtc Exp $";
182116Sjkh#endif
192116Sjkh
202116Sjkh#include "math.h"
212116Sjkh#include "math_private.h"
222116Sjkh
232116Sjkh#ifdef __STDC__
242116Sjkh	int ilogbf(float x)
252116Sjkh#else
262116Sjkh	int ilogbf(x)
272116Sjkh	float x;
282116Sjkh#endif
292116Sjkh{
302116Sjkh	int32_t hx,ix;
312116Sjkh
322116Sjkh	GET_FLOAT_WORD(hx,x);
332116Sjkh	hx &= 0x7fffffff;
342116Sjkh	if(hx<0x00800000) {
352116Sjkh	    if(hx==0)
362116Sjkh		return 0x80000001;	/* ilogb(0) = 0x80000001 */
372116Sjkh	    else			/* subnormal x */
382116Sjkh	        for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
392116Sjkh	    return ix;
402116Sjkh	}
412116Sjkh	else if (hx<0x7f800000) return (hx>>23)-127;
422116Sjkh	else return 0x7fffffff;
432116Sjkh}
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