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/* 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>
#include <float.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;
__uint32_t hx;
GET_FLOAT_WORD(ix,x);
hx = ix&0x7fffffff;
k = hx>>23; /* extract exponent */
if (FLT_UWORD_IS_ZERO(hx))
return x;
if (!FLT_UWORD_IS_FINITE(hx))
return x+x; /* NaN or Inf */
if (FLT_UWORD_IS_SUBNORMAL(hx)) {
x *= two25;
GET_FLOAT_WORD(ix,x);
k = ((ix&0x7f800000)>>23) - 25;
if (n< -50000) return tiny*x; /*underflow*/
}
k = k+n;
if (k > FLT_LARGEST_EXP) return huge*copysignf(huge,x); /* overflow */
if (k > 0) /* normal result */
{SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
if (k < FLT_SMALLEST_EXP) {
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) */
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