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Annotation of OpenXM_contrib/gmp/mpz/gcdext.c, Revision 1.1

1.1     ! maekawa     1: /* mpz_gcdext(g, s, t, a, b) -- Set G to gcd(a, b), and S and T such that
        !             2:    g = as + bt.
        !             3:
        !             4: Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
        !             5:
        !             6: This file is part of the GNU MP Library.
        !             7:
        !             8: The GNU MP Library is free software; you can redistribute it and/or modify
        !             9: it under the terms of the GNU Library General Public License as published by
        !            10: the Free Software Foundation; either version 2 of the License, or (at your
        !            11: option) any later version.
        !            12:
        !            13: The GNU MP 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 Library General Public
        !            16: License for more details.
        !            17:
        !            18: You should have received a copy of the GNU Library General Public License
        !            19: along with the GNU MP 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 "gmp.h"
        !            24: #include "gmp-impl.h"
        !            25:
        !            26: /* Botch:  SLOW!  */
        !            27:
        !            28: void
        !            29: #if __STDC__
        !            30: mpz_gcdext (mpz_ptr g, mpz_ptr s, mpz_ptr t, mpz_srcptr a, mpz_srcptr b)
        !            31: #else
        !            32: mpz_gcdext (g, s, t, a, b)
        !            33:      mpz_ptr g;
        !            34:      mpz_ptr s;
        !            35:      mpz_ptr t;
        !            36:      mpz_srcptr a;
        !            37:      mpz_srcptr b;
        !            38: #endif
        !            39: {
        !            40:   mpz_t s0, s1, q, r, x, d0, d1;
        !            41:
        !            42:   mpz_init_set_ui (s0, 1L);
        !            43:   mpz_init_set_ui (s1, 0L);
        !            44:   mpz_init (q);
        !            45:   mpz_init (r);
        !            46:   mpz_init (x);
        !            47:   mpz_init_set (d0, a);
        !            48:   mpz_init_set (d1, b);
        !            49:
        !            50:   while (d1->_mp_size != 0)
        !            51:     {
        !            52:       mpz_tdiv_qr (q, r, d0, d1);
        !            53:       mpz_set (d0, d1);
        !            54:       mpz_set (d1, r);
        !            55:
        !            56:       mpz_mul (x, s1, q);
        !            57:       mpz_sub (x, s0, x);
        !            58:       mpz_set (s0, s1);
        !            59:       mpz_set (s1, x);
        !            60:     }
        !            61:
        !            62:   if (t != NULL)
        !            63:     {
        !            64:       mpz_mul (x, s0, a);
        !            65:       mpz_sub (x, d0, x);
        !            66:       if (b->_mp_size == 0)
        !            67:        t->_mp_size = 0;
        !            68:       else
        !            69:        mpz_tdiv_q (t, x, b);
        !            70:     }
        !            71:   mpz_set (s, s0);
        !            72:   mpz_set (g, d0);
        !            73:   if (g->_mp_size < 0)
        !            74:     {
        !            75:       g->_mp_size = -g->_mp_size;
        !            76:       s->_mp_size = -s->_mp_size;
        !            77:       if (t != NULL)
        !            78:        t->_mp_size = -t->_mp_size;
        !            79:     }
        !            80:
        !            81:   mpz_clear (s0);
        !            82:   mpz_clear (s1);
        !            83:   mpz_clear (q);
        !            84:   mpz_clear (r);
        !            85:   mpz_clear (x);
        !            86:   mpz_clear (d0);
        !            87:   mpz_clear (d1);
        !            88: }