newlib-cygwin/newlib/libm/common/sf_scalbln.c

72 lines
1.8 KiB
C

/* s_scalbnf.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"
#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 scalblnf (float x, long int n)
#else
float scalblnf (x,n)
float x; long 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 (k==0xff) return x+x; /* NaN or Inf */
k = k+n;
if (n> 50000 || k > 0xfe)
return huge*copysignf(huge,x); /* overflow */
if (n< -50000)
return tiny*copysignf(tiny,x); /*underflow*/
if (k > 0) /* normal result */
{SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
if (k <= -25)
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 scalbln (double x, long int n)
#else
double scalbln (x,n)
double x; long int n;
#endif
{
return (double) scalblnf((float) x, n);
}
#endif /* defined(_DOUBLE_IS_32BITS) */