/* @(#)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.
 * ====================================================
 */

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_frexp.c,v 1.9 1995/05/10 20:47:24 jtc 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>
#include <libm-alias-double.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 + x;                                           /* 0,inf,nan */
  if (ix < 0x00100000)                  /* subnormal */
    {
      x *= two54;
      GET_HIGH_WORD (hx, x);
      ix = hx & 0x7fffffff;
      *eptr = -54;
    }
  *eptr += (ix >> 20) - 1022;
  hx = (hx & 0x800fffff) | 0x3fe00000;
  SET_HIGH_WORD (x, hx);
  return x;
}
libm_alias_double (__frexp, frexp)