forked from KolibriOS/kolibrios
87 lines
2.1 KiB
C
87 lines
2.1 KiB
C
|
/* 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) */
|