Annotation of OpenXM_contrib/gmp/mpz/gcdext.c, Revision 1.1.1.2
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:
1.1.1.2 ! maekawa 4: Copyright (C) 1991, 1993, 1994, 1995, 1996, 1997, 2000 Free Software
! 5: Foundation, Inc.
1.1 maekawa 6:
7: This file is part of the GNU MP Library.
8:
9: The GNU MP Library is free software; you can redistribute it and/or modify
1.1.1.2 ! maekawa 10: it under the terms of the GNU Lesser General Public License as published by
! 11: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1 maekawa 12: option) any later version.
13:
14: The GNU MP Library is distributed in the hope that it will be useful, but
15: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.1.1.2 ! maekawa 16: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
1.1 maekawa 17: License for more details.
18:
1.1.1.2 ! maekawa 19: You should have received a copy of the GNU Lesser General Public License
1.1 maekawa 20: along with the GNU MP Library; see the file COPYING.LIB. If not, write to
21: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
22: MA 02111-1307, USA. */
23:
1.1.1.2 ! maekawa 24: #include <stdio.h> /* for NULL */
1.1 maekawa 25: #include "gmp.h"
26: #include "gmp-impl.h"
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: {
1.1.1.2 ! maekawa 40: mp_size_t asize, bsize, usize, vsize;
! 41: mp_srcptr ap, bp;
! 42: mp_ptr up, vp;
! 43: mp_size_t gsize, ssize, tmp_ssize;
! 44: mp_ptr gp, sp, tmp_gp, tmp_sp;
! 45: mpz_srcptr u, v;
! 46: mpz_ptr ss, tt;
! 47: __mpz_struct stmp, gtmp;
! 48: TMP_DECL (marker);
! 49:
! 50: TMP_MARK (marker);
! 51:
! 52: /* mpn_gcdext requires that U >= V. Therefore, we often have to swap U and
! 53: V. This in turn leads to a lot of complications. The computed cofactor
! 54: will be the wrong one, so we have to fix that up at the end. */
! 55:
! 56: asize = ABS (SIZ (a));
! 57: bsize = ABS (SIZ (b));
! 58: ap = PTR (a);
! 59: bp = PTR (b);
! 60: if (asize > bsize || (asize == bsize && mpn_cmp (ap, bp, asize) > 0))
! 61: {
! 62: usize = asize;
! 63: vsize = bsize;
! 64: up = (mp_ptr) TMP_ALLOC ((usize + 1) * BYTES_PER_MP_LIMB);
! 65: vp = (mp_ptr) TMP_ALLOC ((vsize + 1) * BYTES_PER_MP_LIMB);
! 66: MPN_COPY (up, ap, usize);
! 67: MPN_COPY (vp, bp, vsize);
! 68: u = a;
! 69: v = b;
! 70: ss = s;
! 71: tt = t;
! 72: }
! 73: else
! 74: {
! 75: usize = bsize;
! 76: vsize = asize;
! 77: up = (mp_ptr) TMP_ALLOC ((usize + 1) * BYTES_PER_MP_LIMB);
! 78: vp = (mp_ptr) TMP_ALLOC ((vsize + 1) * BYTES_PER_MP_LIMB);
! 79: MPN_COPY (up, bp, usize);
! 80: MPN_COPY (vp, ap, vsize);
! 81: u = b;
! 82: v = a;
! 83: ss = t;
! 84: tt = s;
! 85: }
1.1 maekawa 86:
1.1.1.2 ! maekawa 87: tmp_gp = (mp_ptr) TMP_ALLOC ((usize + 1) * BYTES_PER_MP_LIMB);
! 88: tmp_sp = (mp_ptr) TMP_ALLOC ((usize + 1) * BYTES_PER_MP_LIMB);
1.1 maekawa 89:
1.1.1.2 ! maekawa 90: if (vsize == 0)
1.1 maekawa 91: {
1.1.1.2 ! maekawa 92: tmp_sp[0] = 1;
! 93: tmp_ssize = 1;
! 94: MPN_COPY (tmp_gp, up, usize);
! 95: gsize = usize;
1.1 maekawa 96: }
1.1.1.2 ! maekawa 97: else
! 98: gsize = mpn_gcdext (tmp_gp, tmp_sp, &tmp_ssize, up, usize, vp, vsize);
! 99: ssize = ABS (tmp_ssize);
1.1 maekawa 100:
1.1.1.2 ! maekawa 101: PTR (>mp) = tmp_gp;
! 102: SIZ (>mp) = gsize;
! 103:
! 104: PTR (&stmp) = tmp_sp;
! 105: SIZ (&stmp) = (tmp_ssize ^ SIZ (u)) >= 0 ? ssize : -ssize;
! 106:
! 107: if (tt != NULL)
1.1 maekawa 108: {
1.1.1.2 ! maekawa 109: if (SIZ (v) == 0)
! 110: SIZ (tt) = 0;
1.1 maekawa 111: else
1.1.1.2 ! maekawa 112: {
! 113: mpz_t x;
! 114: MPZ_TMP_INIT (x, ssize + usize + 1);
! 115: mpz_mul (x, &stmp, u);
! 116: mpz_sub (x, >mp, x);
! 117: mpz_tdiv_q (tt, x, v);
! 118: }
1.1 maekawa 119: }
1.1.1.2 ! maekawa 120:
! 121: if (ss != NULL)
1.1 maekawa 122: {
1.1.1.2 ! maekawa 123: if (ALLOC (ss) < ssize)
! 124: _mpz_realloc (ss, ssize);
! 125: sp = PTR (ss);
! 126: MPN_COPY (sp, tmp_sp, ssize);
! 127: SIZ (ss) = SIZ (&stmp);
1.1 maekawa 128: }
129:
1.1.1.2 ! maekawa 130: if (ALLOC (g) < gsize)
! 131: _mpz_realloc (g, gsize);
! 132: gp = PTR (g);
! 133: MPN_COPY (gp, tmp_gp, gsize);
! 134: SIZ (g) = gsize;
! 135:
! 136: TMP_FREE (marker);
1.1 maekawa 137: }
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