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/* ef_sqrtf.c -- float version of e_sqrt.c.

 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.

 */

/*

 * ====================================================

 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

 *

 * Developed at SunPro, a Sun Microsystems, Inc. business.

 * Permission to use, copy, modify, and distribute this

 * software is freely granted, provided that this notice

 * is preserved.

 * ====================================================

 */

#include "fdlibm.h"

#ifdef __STDC__

static  const float     one     = 1.0, tiny=1.0e-30;

#else

static  float   one     = 1.0, tiny=1.0e-30;

#endif

#ifdef __STDC__

        float __ieee754_sqrtf(float x)

#else

        float __ieee754_sqrtf(x)

        float x;

#endif

{

        float z;

        __int32_t       sign = (__int32_t)0x80000000;

        __uint32_t r;

        __int32_t ix,s,q,m,t,i;

        GET_FLOAT_WORD(ix,x);

    /* take care of Inf and NaN */

        if((ix&0x7f800000L)==0x7f800000L) {

            return x*x+x;               /* sqrt(NaN)=NaN, sqrt(+inf)=+inf

                                           sqrt(-inf)=sNaN */

        }

    /* take care of zero */

        if(ix<=0) {

            if((ix&(~sign))==0) return x;/* sqrt(+-0) = +-0 */

            else if(ix<0)

                return (x-x)/(x-x);             /* sqrt(-ve) = sNaN */

        }

    /* normalize x */

        m = (ix>>23);

        if(m==0) {                               /* subnormal x */

            for(i=0;(ix&0x00800000L)==0;i++) ix<<=1;

            m -= i-1;

        }

        m -= 127;       /* unbias exponent */

        ix = (ix&0x007fffffL)|0x00800000L;

        if(m&1) /* odd m, double x to make it even */

            ix += ix;

        m >>= 1;        /* m = [m/2] */

    /* generate sqrt(x) bit by bit */

        ix += ix;

        q = s = 0;               /* q = sqrt(x) */

        r = 0x01000000L;                /* r = moving bit from right to left */

        while(r!=0) {

            t = s+r;

            if(t<=ix) {

                s    = t+r;

                ix  -= t;

                q   += r;

            }

            ix += ix;

            r>>=1;

        }

    /* use floating add to find out rounding direction */

        if(ix!=0) {

            z = one-tiny; /* trigger inexact flag */

            if (z>=one) {

                z = one+tiny;

                if (z>one)

                    q += 2;

                else

                    q += (q&1);

            }

        }

        ix = (q>>1)+0x3f000000L;

        ix += (m <<23);

        SET_FLOAT_WORD(z,ix);

        return z;

}