mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-11 07:40:05 +00:00
54 lines
1.6 KiB
C
54 lines
1.6 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 <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 (__builtin_expect(k==0, 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 (__builtin_expect(k==0xff, 0)) return x+x; /* NaN or Inf */
|
|
if (__builtin_expect(n< -50000, 0))
|
|
return tiny*__copysignf(tiny,x); /*underflow*/
|
|
if (__builtin_expect(n> 50000 || k+n > 0xfe, 0))
|
|
return huge*__copysignf(huge,x); /* overflow */
|
|
/* Now k and n are bounded we know that k = k+n does not
|
|
overflow. */
|
|
k = k+n;
|
|
if (__builtin_expect(k > 0, 1)) /* 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;
|
|
}
|
|
weak_alias (__scalbnf, scalbnf)
|