Return to eq.c CVS log

Up to [local] / OpenXM_contrib / gmp / mpf

Annotation of OpenXM_contrib/gmp/mpf/eq.c, Revision 1.1.1.3

1.1       maekawa     1: /* mpf_eq -- Compare two floats up to a specified bit #.
                      2:
1.1.1.3 ! ohara       3: Copyright 1993, 1995, 1996, 2001, 2002 Free Software Foundation, Inc.
1.1       maekawa     4:
                      5: This file is part of the GNU MP Library.
                      6:
                      7: The GNU MP Library is free software; you can redistribute it and/or modify
1.1.1.2   maekawa     8: it under the terms of the GNU Lesser General Public License as published by
                      9: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1       maekawa    10: option) any later version.
                     11:
                     12: The GNU MP Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.1.1.2   maekawa    14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
1.1       maekawa    15: License for more details.
                     16:
1.1.1.2   maekawa    17: You should have received a copy of the GNU Lesser General Public License
1.1       maekawa    18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20: MA 02111-1307, USA. */
                     21:
                     22: #include "gmp.h"
                     23: #include "gmp-impl.h"
                     24:
                     25: int
                     26: mpf_eq (mpf_srcptr u, mpf_srcptr v, unsigned long int n_bits)
                     27: {
                     28:   mp_srcptr up, vp;
                     29:   mp_size_t usize, vsize, size, i;
                     30:   mp_exp_t uexp, vexp;
                     31:   int usign;
                     32:
                     33:   uexp = u->_mp_exp;
                     34:   vexp = v->_mp_exp;
                     35:
                     36:   usize = u->_mp_size;
                     37:   vsize = v->_mp_size;
                     38:
                     39:   /* 1. Are the signs different?  */
                     40:   if ((usize ^ vsize) >= 0)
                     41:     {
                     42:       /* U and V are both non-negative or both negative.  */
                     43:       if (usize == 0)
                     44:        return vsize == 0;
                     45:       if (vsize == 0)
                     46:        return 0;
                     47:
                     48:       /* Fall out.  */
                     49:     }
                     50:   else
                     51:     {
                     52:       /* Either U or V is negative, but not both.  */
                     53:       return 0;
                     54:     }
                     55:
                     56:   /* U and V have the same sign and are both non-zero.  */
                     57:
                     58:   usign = usize >= 0 ? 1 : -1;
                     59:
                     60:   /* 2. Are the exponents different?  */
                     61:   if (uexp > vexp)
                     62:     return 0;                  /* ??? handle (uexp = vexp + 1)   */
                     63:   if (vexp > uexp)
                     64:     return 0;                  /* ??? handle (vexp = uexp + 1)   */
                     65:
                     66:   usize = ABS (usize);
                     67:   vsize = ABS (vsize);
                     68:
                     69:   up = u->_mp_d;
                     70:   vp = v->_mp_d;
                     71:
                     72:   /* Ignore zeroes at the low end of U and V.  */
                     73:   while (up[0] == 0)
                     74:     {
                     75:       up++;
                     76:       usize--;
                     77:     }
                     78:   while (vp[0] == 0)
                     79:     {
                     80:       vp++;
                     81:       vsize--;
                     82:     }
                     83:
                     84:   if (usize > vsize)
                     85:     {
1.1.1.3 ! ohara      86:       if (vsize * GMP_NUMB_BITS < n_bits)
1.1       maekawa    87:        return 0;               /* surely too different */
                     88:       size = vsize;
                     89:     }
                     90:   else if (vsize > usize)
                     91:     {
1.1.1.3 ! ohara      92:       if (usize * GMP_NUMB_BITS < n_bits)
1.1       maekawa    93:        return 0;               /* surely too different */
                     94:       size = usize;
                     95:     }
                     96:   else
                     97:     {
                     98:       size = usize;
                     99:     }
                    100:
1.1.1.3 ! ohara     101:   if (size > (n_bits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
        !           102:     size = (n_bits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS;
1.1       maekawa   103:
                    104:   up += usize - size;
                    105:   vp += vsize - size;
                    106:
                    107:   for (i = size - 1; i >= 0; i--)
                    108:     {
                    109:       if (up[i] != vp[i])
                    110:        return 0;
                    111:     }
                    112:
                    113:   return 1;
                    114: }