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Annotation of OpenXM_contrib/gmp/mpf/eq.c, Revision 1.1

1.1     ! maekawa     1: /* mpf_eq -- Compare two floats up to a specified bit #.
        !             2:
        !             3: Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc.
        !             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
        !             8: it under the terms of the GNU Library General Public License as published by
        !             9: the Free Software Foundation; either version 2 of the License, or (at your
        !            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
        !            14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Library General Public License
        !            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: #if __STDC__
        !            27: mpf_eq (mpf_srcptr u, mpf_srcptr v, unsigned long int n_bits)
        !            28: #else
        !            29: mpf_eq (u, v, n_bits)
        !            30:      mpf_srcptr u;
        !            31:      mpf_srcptr v;
        !            32:      unsigned long int n_bits;
        !            33: #endif
        !            34: {
        !            35:   mp_srcptr up, vp;
        !            36:   mp_size_t usize, vsize, size, i;
        !            37:   mp_exp_t uexp, vexp;
        !            38:   int usign;
        !            39:
        !            40:   uexp = u->_mp_exp;
        !            41:   vexp = v->_mp_exp;
        !            42:
        !            43:   usize = u->_mp_size;
        !            44:   vsize = v->_mp_size;
        !            45:
        !            46:   /* 1. Are the signs different?  */
        !            47:   if ((usize ^ vsize) >= 0)
        !            48:     {
        !            49:       /* U and V are both non-negative or both negative.  */
        !            50:       if (usize == 0)
        !            51:        return vsize == 0;
        !            52:       if (vsize == 0)
        !            53:        return 0;
        !            54:
        !            55:       /* Fall out.  */
        !            56:     }
        !            57:   else
        !            58:     {
        !            59:       /* Either U or V is negative, but not both.  */
        !            60:       return 0;
        !            61:     }
        !            62:
        !            63:   /* U and V have the same sign and are both non-zero.  */
        !            64:
        !            65:   usign = usize >= 0 ? 1 : -1;
        !            66:
        !            67:   /* 2. Are the exponents different?  */
        !            68:   if (uexp > vexp)
        !            69:     return 0;                  /* ??? handle (uexp = vexp + 1)   */
        !            70:   if (vexp > uexp)
        !            71:     return 0;                  /* ??? handle (vexp = uexp + 1)   */
        !            72:
        !            73:   usize = ABS (usize);
        !            74:   vsize = ABS (vsize);
        !            75:
        !            76:   up = u->_mp_d;
        !            77:   vp = v->_mp_d;
        !            78:
        !            79:   /* Ignore zeroes at the low end of U and V.  */
        !            80:   while (up[0] == 0)
        !            81:     {
        !            82:       up++;
        !            83:       usize--;
        !            84:     }
        !            85:   while (vp[0] == 0)
        !            86:     {
        !            87:       vp++;
        !            88:       vsize--;
        !            89:     }
        !            90:
        !            91:   if (usize > vsize)
        !            92:     {
        !            93:       if (vsize * BITS_PER_MP_LIMB < n_bits)
        !            94:        return 0;               /* surely too different */
        !            95:       size = vsize;
        !            96:     }
        !            97:   else if (vsize > usize)
        !            98:     {
        !            99:       if (usize * BITS_PER_MP_LIMB < n_bits)
        !           100:        return 0;               /* surely too different */
        !           101:       size = usize;
        !           102:     }
        !           103:   else
        !           104:     {
        !           105:       size = usize;
        !           106:     }
        !           107:
        !           108:   if (size > (n_bits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB)
        !           109:     size = (n_bits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;
        !           110:
        !           111:   up += usize - size;
        !           112:   vp += vsize - size;
        !           113:
        !           114:   for (i = size - 1; i >= 0; i--)
        !           115:     {
        !           116:       if (up[i] != vp[i])
        !           117:        return 0;
        !           118:     }
        !           119:
        !           120:   return 1;
        !           121: }