53 lines
1.3 KiB
C
53 lines
1.3 KiB
C
|
/* @(#)s_frexp.c 5.1 93/09/24 */
|
||
|
|
/*
|
||
|
|
* ====================================================
|
||
|
|
* 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 <sys/cdefs.h>
|
||
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
||
|
|
__RCSID("$NetBSD: s_frexp.c,v 1.13 2008/09/28 18:54:55 christos Exp $");
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/*
|
||
|
|
* for non-zero x
|
||
|
|
* x = 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 frexp(arg,&exp) returns arg
|
||
|
|
* with *exp=0.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "math.h"
|
||
|
|
#include "math_private.h"
|
||
|
|
|
||
|
|
static const double
|
||
|
|
two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
|
||
|
|
|
||
|
|
double
|
||
|
|
frexp(double x, int *eptr)
|
||
|
|
{
|
||
|
|
int32_t hx, ix, lx;
|
||
|
|
EXTRACT_WORDS(hx,lx,x);
|
||
|
|
ix = 0x7fffffff&hx;
|
||
|
|
*eptr = 0;
|
||
|
|
if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */
|
||
|
|
if (ix<0x00100000) { /* subnormal */
|
||
|
|
x *= two54;
|
||
|
|
GET_HIGH_WORD(hx,x);
|
||
|
|
ix = hx&0x7fffffff;
|
||
|
|
*eptr = -54;
|
||
|
|
}
|
||
|
|
*eptr += ((uint32_t)ix>>20)-1022;
|
||
|
|
hx = (hx&0x800fffff)|0x3fe00000;
|
||
|
|
SET_HIGH_WORD(x,hx);
|
||
|
|
return x;
|
||
|
|
}
|