text: /* mpf_eq -- Compare two floats up to a specified bit #.
  
  Copyright 1993, 1995, 1996, 2001, 2002, 2008, 2009 Free Software Foundation,
  Inc.
  
  This file is part of the GNU MP Library.
  
  The GNU MP Library is free software; you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 3 of the License, or (at your
  option) any later version.
  
  The GNU MP Library is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  License for more details.
  
  You should have received a copy of the GNU Lesser General Public License
  along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  
  #include "gmp.h"
  #include "gmp-impl.h"
  #include "longlong.h"
  
  int
  mpf_eq (mpf_srcptr u, mpf_srcptr v, mp_bitcnt_t n_bits)
  {
    mp_srcptr up, vp, p;
    mp_size_t usize, vsize, minsize, maxsize, n_limbs, i, size;
    mp_exp_t uexp, vexp;
    mp_limb_t diff;
    int cnt;
  
    uexp = u->_mp_exp;
    vexp = v->_mp_exp;
  
    usize = u->_mp_size;
    vsize = v->_mp_size;
  
    /* 1. Are the signs different?  */
    if ((usize ^ vsize) >= 0)
      {
        /* U and V are both non-negative or both negative.  */
        if (usize == 0)
  	return vsize == 0;
        if (vsize == 0)
  	return 0;
  
        /* Fall out.  */
      }
    else
      {
        /* Either U or V is negative, but not both.  */
        return 0;
      }
  
    /* U and V have the same sign and are both non-zero.  */
  
    /* 2. Are the exponents different?  */
    if (uexp != vexp)
      return 0;
  
    usize = ABS (usize);
    vsize = ABS (vsize);
  
    up = u->_mp_d;
    vp = v->_mp_d;
  
    up += usize;			/* point just above most significant limb */
    vp += vsize;			/* point just above most significant limb */
  
    count_leading_zeros (cnt, up[-1]);
    if ((vp[-1] >> (GMP_LIMB_BITS - 1 - cnt)) != 1)
      return 0;			/* msb positions different */
  
    n_bits += cnt - GMP_NAIL_BITS;
    n_limbs = (n_bits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS;
  
    usize = MIN (usize, n_limbs);
    vsize = MIN (vsize, n_limbs);
  
  #if 0
    /* Ignore zeros at the low end of U and V.  */
    while (up[0] == 0)
      up++, usize--;
    while (vp[0] == 0)
      vp++, vsize--;
  #endif
  
    minsize = MIN (usize, vsize);
    maxsize = usize + vsize - minsize;
  
    up -= minsize;		/* point at most significant common limb */
    vp -= minsize;		/* point at most significant common limb */
  
    /* Compare the most significant part which has explicit limbs for U and V. */
    for (i = minsize - 1; i > 0; i--)
      {
        if (up[i] != vp[i])
  	return 0;
      }
  
    n_bits -= (maxsize - 1) * GMP_NUMB_BITS;
  
    size = maxsize - minsize;
    if (size != 0)
      {
        if (up[0] != vp[0])
  	return 0;
  
        /* Now either U or V has its limbs consumed, i.e, continues with an
  	 infinite number of implicit zero limbs.  Check that the other operand
  	 has just zeros in the corresponding, relevant part.  */
  
        if (usize > vsize)
  	p = up - size;
        else
  	p = vp - size;
  
        for (i = size - 1; i > 0; i--)
  	{
  	  if (p[i] != 0)
  	    return 0;
  	}
  
        diff = p[0];
      }
    else
      {
        /* Both U or V has its limbs consumed.  */
  
        diff = up[0] ^ vp[0];
      }
  
    if (n_bits < GMP_NUMB_BITS)
      diff >>= GMP_NUMB_BITS - n_bits;
  
    return diff == 0;
  }
  