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[/] [or1k/] [trunk/] [newlib-1.10.0/] [newlib/] [libm/] [mathfp/] [ef_hypot.c] - Blame information for rev 1765

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1 1010 ivang 
/* ef_hypot.c -- float version of e_hypot.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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#include "fdlibm.h"
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#ifdef __STDC__
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        float hypotf(float x, float y)
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#else
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        float hypotf(x,y)
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        float x, y;
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#endif
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{
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        float a=x,b=y,t1,t2,y1,y2,w;
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        __int32_t j,k,ha,hb;
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        GET_FLOAT_WORD(ha,x);
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        ha &= 0x7fffffffL;
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        GET_FLOAT_WORD(hb,y);
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        hb &= 0x7fffffffL;
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        if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
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        SET_FLOAT_WORD(a,ha);   /* a <- |a| */
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        SET_FLOAT_WORD(b,hb);   /* b <- |b| */
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        if((ha-hb)>0xf000000L) {return a+b;} /* x/y > 2**30 */
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        k=0;
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        if(ha > 0x58800000L) {  /* a>2**50 */
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           if(ha >= 0x7f800000L) {      /* Inf or NaN */
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               w = a+b;                 /* for sNaN */
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               if(ha == 0x7f800000L) w = a;
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               if(hb == 0x7f800000L) w = b;
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               return w;
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           }
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           /* scale a and b by 2**-60 */
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           ha -= 0x5d800000L; hb -= 0x5d800000L;        k += 60;
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           SET_FLOAT_WORD(a,ha);
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           SET_FLOAT_WORD(b,hb);
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        }
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        if(hb < 0x26800000L) {  /* b < 2**-50 */
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            if(hb <= 0x007fffffL) {     /* subnormal b or 0 */
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                if(hb==0) return a;
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                SET_FLOAT_WORD(t1,0x3f000000L); /* t1=2^126 */
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                b *= t1;
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                a *= t1;
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                k -= 126;
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            } else {            /* scale a and b by 2^60 */
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                ha += 0x5d800000;       /* a *= 2^60 */
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                hb += 0x5d800000;       /* b *= 2^60 */
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                k -= 60;
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                SET_FLOAT_WORD(a,ha);
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                SET_FLOAT_WORD(b,hb);
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            }
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        }
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    /* medium size a and b */
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        w = a-b;
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        if (w>b) {
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            SET_FLOAT_WORD(t1,ha&0xfffff000L);
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            t2 = a-t1;
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            w  = sqrtf(t1*t1-(b*(-b)-t2*(a+t1)));
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        } else {
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            a  = a+a;
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            SET_FLOAT_WORD(y1,hb&0xfffff000L);
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            y2 = b - y1;
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            SET_FLOAT_WORD(t1,ha+0x00800000L);
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            t2 = a - t1;
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            w  = sqrtf(t1*y1-(w*(-w)-(t1*y2+t2*b)));
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        }
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        if(k!=0) {
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            SET_FLOAT_WORD(t1,0x3f800000L+(k<<23));
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            return t1*w;
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        } else return w;
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}

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