s_logbf.c revision 2116 
12116Sjkh/* s_logbf.c -- float version of s_logb.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_logbf.c,v 1.2 1994/08/18 23:07:07 jtc Exp $";
182116Sjkh#endif
192116Sjkh
202116Sjkh#include "math.h"
212116Sjkh#include "math_private.h"
222116Sjkh
232116Sjkh#ifdef __STDC__
242116Sjkh	float logbf(float x)
252116Sjkh#else
262116Sjkh	float logbf(x)
272116Sjkh	float x;
282116Sjkh#endif
292116Sjkh{
302116Sjkh	int32_t ix;
312116Sjkh	GET_FLOAT_WORD(ix,x);
322116Sjkh	ix &= 0x7fffffff;			/* high |x| */
332116Sjkh	if(ix==0) return (float)-1.0/fabsf(x);
342116Sjkh	if(ix>=0x7f800000) return x*x;
352116Sjkh	if((ix>>=23)==0) 			/* IEEE 754 logb */
362116Sjkh		return -126.0;
372116Sjkh	else
382116Sjkh		return (float) (ix-127);
392116Sjkh}
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