Subversion Repositories or1k_old

/* sf_scalbn.c -- float version of s_scalbn.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"

#include <limits.h>

#if INT_MAX > 50000

#define OVERFLOW_INT 50000

#else

#define OVERFLOW_INT 30000

#endif

#ifdef __STDC__

static const float

#else

static float

#endif

two25   =  3.355443200e+07,     /* 0x4c000000 */

twom25  =  2.9802322388e-08,    /* 0x33000000 */

huge   = 1.0e+30,

tiny   = 1.0e-30;

#ifdef __STDC__

        float scalbnf (float x, int n)

#else

        float scalbnf (x,n)

        float x; int n;

#endif

{

        __int32_t  k,ix;

        GET_FLOAT_WORD(ix,x);

        k = (ix&0x7f800000)>>23;                /* extract exponent */

        if (k==0) {                              /* 0 or subnormal x */

            if ((ix&0x7fffffff)==0) return x; /* +-0 */

            x *= two25;

            GET_FLOAT_WORD(ix,x);

            k = ((ix&0x7f800000)>>23) - 25;

            if (n< -50000) return tiny*x;       /*underflow*/

            }

        if (k==0xff) return x+x;                /* NaN or Inf */

        k = k+n;

        if (k >  0xfe) return huge*copysignf(huge,x); /* overflow  */

        if (k > 0)                               /* normal result */

            {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}

        if (k <= -25)

            if (n > OVERFLOW_INT)       /* in case integer overflow in n+k */

                return huge*copysignf(huge,x);  /*overflow*/

            else return tiny*copysignf(tiny,x); /*underflow*/

        k += 25;                                /* subnormal result */

        SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));

        return x*twom25;

}

#ifdef _DOUBLE_IS_32BITS

#ifdef __STDC__

        double scalbn(double x, int n)

#else

        double scalbn(x,n)

        double x;

        int n;

#endif

{

        return (double) scalbnf((float) x, n);

}

#endif /* defined(_DOUBLE_IS_32BITS) */