ref: ac1a4e7dbe0b0c96054aee63bdd167636e857b85
dir: /posix/s_scalbnf.c/
/* s_scalbnf.c -- float version of s_scalbn.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, [email protected].
*/
/*
* ====================================================
* 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 "math.h"
#include "math_private.h"
static const float
two25 = 3.355443200e+07, /* 0x4c000000 */
twom25 = 2.9802322388e-08, /* 0x33000000 */
huge = 1.0e+30,
tiny = 1.0e-30;
float
scalbnf(float x, int n)
{
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 > 50000) /* 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;
}
float
ldexpf(float x, int n)
{
return scalbnf(x, n);
}