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Annotation of OpenXM_contrib/gmp/mpfr/eq.c, Revision 1.1.1.1

1.1       ohara       1: /* mpfr_eq -- Compare two floats up to a specified bit #.
                      2:
                      3: Copyright 1999, 2001 Free Software Foundation, Inc.
                      4: (Copied from GNU MP, file mpf_eq.)
                      5:
                      6: This file is part of the MPFR Library.
                      7:
                      8: The MPFR Library is free software; you can redistribute it and/or modify
                      9: it under the terms of the GNU Lesser General Public License as published by
                     10: the Free Software Foundation; either version 2.1 of the License, or (at your
                     11: option) any later version.
                     12:
                     13: The MPFR Library is distributed in the hope that it will be useful, but
                     14: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     15: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
                     16: License for more details.
                     17:
                     18: You should have received a copy of the GNU Lesser General Public License
                     19: along with the MPFR Library; see the file COPYING.LIB.  If not, write to
                     20: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     21: MA 02111-1307, USA. */
                     22:
                     23: #include <stdio.h>
                     24: #include "gmp.h"
                     25: #include "gmp-impl.h"
                     26: #include "mpfr.h"
                     27: #include "mpfr-impl.h"
                     28:
                     29: int
                     30: mpfr_eq (mpfr_srcptr u, mpfr_srcptr v, unsigned long int n_bits)
                     31: {
                     32:   mp_srcptr up, vp;
                     33:   mp_size_t usize, vsize, size, i;
                     34:   mp_exp_t uexp, vexp;
                     35:   int usign, k;
                     36:
                     37:   uexp = MPFR_EXP(u);
                     38:   vexp = MPFR_EXP(v);
                     39:
                     40:   usize = (MPFR_PREC(u)-1)/BITS_PER_MP_LIMB + 1;
                     41:   vsize = (MPFR_PREC(v)-1)/BITS_PER_MP_LIMB + 1;
                     42:
                     43:   usign = MPFR_SIGN(u);
                     44:
                     45:   /* 1. Are the signs different?  */
                     46:   if (usign ==  MPFR_SIGN(v))
                     47:     {
                     48:       /* U and V are both non-negative or both negative.  */
                     49:       if (!MPFR_NOTZERO(u))
                     50:        return !MPFR_NOTZERO(v);
                     51:       if (!MPFR_NOTZERO(v))
                     52:        return !MPFR_NOTZERO(u);
                     53:
                     54:       /* Fall out.  */
                     55:     }
                     56:   else
                     57:     {
                     58:       /* Either U or V is negative, but not both.  */
                     59:       if (MPFR_NOTZERO(u) || MPFR_NOTZERO(v))
                     60:        return 0;
                     61:       else return 1; /* particular case -0 = +0 */
                     62:     }
                     63:
                     64:   /* U and V have the same sign and are both non-zero.  */
                     65:   if (MPFR_IS_INF(u))
                     66:     return (MPFR_IS_INF(v) && (usign == MPFR_SIGN(v)));
                     67:   else if (MPFR_IS_INF(v)) return 0;
                     68:
                     69:   if (MPFR_IS_NAN(u) || MPFR_IS_NAN(v)) return 0;
                     70:
                     71:   /* 2. Are the exponents different?  */
                     72:   if (uexp > vexp)
                     73:     return 0;                  /* ??? handle (uexp = vexp + 1)   */
                     74:   if (vexp > uexp)
                     75:     return 0;                  /* ??? handle (vexp = uexp + 1)   */
                     76:
                     77:   usize = ABS (usize);
                     78:   vsize = ABS (vsize);
                     79:
                     80:   up = MPFR_MANT(u);
                     81:   vp = MPFR_MANT(v);
                     82:
                     83:   if (usize > vsize)
                     84:     {
                     85:       if (vsize * BITS_PER_MP_LIMB < n_bits)
                     86:        {
                     87:          k = usize - vsize - 1;
                     88:          while (k >= 0 && !up[k]) --k;
                     89:          if (k >= 0)
                     90:            return 0;           /* surely too different */
                     91:        }
                     92:       size = vsize;
                     93:     }
                     94:   else if (vsize > usize)
                     95:     {
                     96:       if (usize * BITS_PER_MP_LIMB < n_bits)
                     97:        {
                     98:          k = vsize - usize - 1;
                     99:          while (k >= 0 && !vp[k]) --k;
                    100:          if (k >= 0)
                    101:            return 0;           /* surely too different */
                    102:        }
                    103:       size = usize;
                    104:     }
                    105:   else
                    106:     {
                    107:       size = usize;
                    108:     }
                    109:
                    110:   if (size > (n_bits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB)
                    111:     size = (n_bits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;
                    112:
                    113:   up += usize - size;
                    114:   vp += vsize - size;
                    115:
                    116:   for (i = size - 1; i > 0; i--)
                    117:     {
                    118:       if (up[i] != vp[i])
                    119:        return 0;
                    120:     }
                    121:
                    122:   if (n_bits & (BITS_PER_MP_LIMB - 1))
                    123:     return (up[i] >> (BITS_PER_MP_LIMB - (n_bits & (BITS_PER_MP_LIMB - 1))) ==
                    124:            vp[i] >> (BITS_PER_MP_LIMB - (n_bits & (BITS_PER_MP_LIMB - 1))));
                    125:   else
                    126:     return (up[i] == vp[i]);
                    127: }