You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
57 lines
1.3 KiB
57 lines
1.3 KiB
4 months ago
|
|
||
|
|
/* @(#)s_frexp.c 1.4 95/01/18 */
|
||
|
|
/*
|
||
|
|
* ====================================================
|
||
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
||
|
|
*
|
||
|
|
* Developed at SunSoft, a Sun Microsystems, Inc. business.
|
||
|
|
* Permission to use, copy, modify, and distribute this
|
||
|
|
* software is freely granted, provided that this notice
|
||
|
|
* is preserved.
|
||
|
|
* ====================================================
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
* for non-zero x
|
||
|
|
* x = ieee_frexp(arg,&exp);
|
||
|
|
* return a double fp quantity x such that 0.5 <= |x| <1.0
|
||
|
|
* and the corresponding binary exponent "exp". That is
|
||
|
|
* arg = x*2^exp.
|
||
|
|
* If arg is inf, 0.0, or NaN, then ieee_frexp(arg,&exp) returns arg
|
||
|
|
* with *exp=0.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "fdlibm.h"
|
||
|
|
|
||
|
|
#ifdef __STDC__
|
||
|
|
static const double
|
||
|
|
#else
|
||
|
|
static double
|
||
|
|
#endif
|
||
|
|
two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
|
||
|
|
|
||
|
|
#ifdef __STDC__
|
||
|
|
double ieee_frexp(double x, int *eptr)
|
||
|
|
#else
|
||
|
|
double ieee_frexp(x, eptr)
|
||
|
|
double x; int *eptr;
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
int hx, ix, lx;
|
||
|
|
hx = __HI(x);
|
||
|
|
ix = 0x7fffffff&hx;
|
||
|
|
lx = __LO(x);
|
||
|
|
*eptr = 0;
|
||
|
|
if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */
|
||
|
|
if (ix<0x00100000) { /* subnormal */
|
||
|
|
x *= two54;
|
||
|
|
hx = __HI(x);
|
||
|
|
ix = hx&0x7fffffff;
|
||
|
|
*eptr = -54;
|
||
|
|
}
|
||
|
|
*eptr += (ix>>20)-1022;
|
||
|
|
hx = (hx&0x800fffff)|0x3fe00000;
|
||
|
|
__HI(x) = hx;
|
||
|
|
return x;
|
||
|
|
}
|