Annotation of OpenXM/src/kan96xx/gmp-2.0.2-ssh-2/mpz/gcdext.c, Revision 1.1
1.1 ! takayama 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: }
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