genericopenlibs/openenvcore/libm/src/s_ilogbf.c
author Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
Fri, 11 Jun 2010 15:26:22 +0300
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/*--------------------------------------------------------------------
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 *© Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.
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 *--------------------------------------------------------------------
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*/
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/* s_ilogbf.c -- float version of s_ilogb.c.
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 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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 */
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/*
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 * ====================================================
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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 *
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 * Developed at SunPro, a Sun Microsystems, Inc. business.
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 */
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#ifndef __SYMBIAN32__
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#ifndef lint
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static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_ilogbf.c,v 1.7 2004/10/09 17:14:28 stefanf Exp $";
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#endif
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#endif //__SYMBIAN32__
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#include <limits.h>
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#include <math.h>
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#include "math_private.h"
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EXPORT_C int ilogbf(float x)
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{
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	int32_t hx,ix;
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	GET_FLOAT_WORD(hx,x);
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	hx &= 0x7fffffff;
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	if(hx<0x00800000) {
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	    if(hx==0)
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		return FP_ILOGB0;
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	    else			/* subnormal x */
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	        for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
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	    return ix;
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	}
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	else if (hx<0x7f800000) return (hx>>23)-127;
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	else if (hx>0x7f800000) return FP_ILOGBNAN;
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	else return INT_MAX;
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}