text: /* mpf_eq -- Compare two floats up to a specified bit #.
  
  Copyright 1993, 1995, 1996, 2001, 2002, 2008, 2009, 2012 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 either:
  
    * 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.
  
  or
  
    * the GNU General Public License as published by the Free Software
      Foundation; either version 2 of the License, or (at your option) any
      later version.
  
  or both in parallel, as here.
  
  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 General Public License
  for more details.
  
  You should have received copies of the GNU General Public License and the
  GNU Lesser General Public License along with the GNU MP Library.  If not,
  see https://www.gnu.org/licenses/.  */
  
  #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;
  }
  