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[/] [or1k/] [trunk/] [linux/] [uClibc/] [libm/] [s_ilogb.c] - Blame information for rev 1325

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Line No. Rev Author Line
1 1325 phoenix
/* @(#)s_ilogb.c 5.1 93/09/24 */
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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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: s_ilogb.c,v 1.9 1995/05/10 20:47:28 jtc Exp $";
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#endif
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/* ilogb(double x)
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 * return the binary exponent of non-zero x
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 * ilogb(0) = 0x80000001
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 * ilogb(inf/NaN) = 0x7fffffff (no signal is raised)
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 */
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#include "math.h"
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#include "math_private.h"
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#ifdef __STDC__
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        int ilogb(double x)
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#else
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        int ilogb(x)
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        double x;
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#endif
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{
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        int32_t hx,lx,ix;
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        GET_HIGH_WORD(hx,x);
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        hx &= 0x7fffffff;
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        if(hx<0x00100000) {
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            GET_LOW_WORD(lx,x);
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            if((hx|lx)==0)
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                return 0x80000001;      /* ilogb(0) = 0x80000001 */
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            else                        /* subnormal x */
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                if(hx==0) {
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                    for (ix = -1043; lx>0; lx<<=1) ix -=1;
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                } else {
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                    for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1;
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                }
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            return ix;
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        }
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        else if (hx<0x7ff00000) return (hx>>20)-1023;
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        else return 0x7fffffff;
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}

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