From 11da511c784eca003deb90c23570f0873954e0de Mon Sep 17 00:00:00 2001 From: Duncan Wilkie Date: Sat, 18 Nov 2023 06:11:09 -0600 Subject: Initial commit. --- gmp-6.3.0/mpz/gcdext.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 135 insertions(+) create mode 100644 gmp-6.3.0/mpz/gcdext.c (limited to 'gmp-6.3.0/mpz/gcdext.c') diff --git a/gmp-6.3.0/mpz/gcdext.c b/gmp-6.3.0/mpz/gcdext.c new file mode 100644 index 0000000..b1f73c2 --- /dev/null +++ b/gmp-6.3.0/mpz/gcdext.c @@ -0,0 +1,135 @@ +/* mpz_gcdext(g, s, t, a, b) -- Set G to gcd(a, b), and S and T such that + g = as + bt. + +Copyright 1991, 1993-1997, 2000, 2001, 2005, 2011, 2012, 2015 Free +Software Foundation, Inc. + +This file is part of the GNU MP Library. + +The GNU MP Library is free software; you can redistribute it and/or modify +it under the terms of either: + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at your + option) any later version. + +or + + * the GNU General Public License as published by the Free Software + Foundation; either version 2 of the License, or (at your option) any + later version. + +or both in parallel, as here. + +The GNU MP Library is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. */ + +#include /* for NULL */ +#include "gmp-impl.h" + +void +mpz_gcdext (mpz_ptr g, mpz_ptr s, mpz_ptr t, mpz_srcptr a, mpz_srcptr b) +{ + mp_size_t asize, bsize; + mp_ptr tmp_ap, tmp_bp; + mp_size_t gsize, ssize, tmp_ssize; + mp_ptr gp, tmp_gp, tmp_sp; + TMP_DECL; + + /* mpn_gcdext requires that Usize >= Vsize. Therefore, we often + have to swap U and V. The computed cofactor will be the + "smallest" one, which is faster to produce. The wanted one will + be computed here; this is needed anyway when both are requested. */ + + asize = ABSIZ (a); + bsize = ABSIZ (b); + + ASSERT (s != NULL); + + if (asize < bsize) + { + MPZ_SRCPTR_SWAP (a, b); + MP_SIZE_T_SWAP (asize, bsize); + MPZ_PTR_SWAP (s, t); + } + + if (bsize == 0) + { + /* g = |a|, s = sgn(a), t = 0. */ + ssize = SIZ (a) >= 0 ? (asize != 0) : -1; + + if (g != NULL) + { + /* If g == a, then ALLOC(g) == ALLOC(a) >= asize, i.e. + the next MPZ_NEWALLOC returns the old PTR(a) .*/ + gp = MPZ_NEWALLOC (g, asize); + MPN_COPY (gp, PTR (a), asize); + SIZ (g) = asize; + } + if (t != NULL) + SIZ (t) = 0; + if (s != NULL) + { + SIZ (s) = ssize; + MPZ_NEWALLOC (s, 1)[0] = 1; + } + return; + } + + TMP_MARK; + + TMP_ALLOC_LIMBS_2 (tmp_gp, bsize, tmp_sp, asize + bsize + bsize + 1); + tmp_bp = tmp_sp + bsize + 1; + tmp_ap = tmp_bp + bsize; + MPN_COPY (tmp_ap, PTR (a), asize); + MPN_COPY (tmp_bp, PTR (b), bsize); + + gsize = mpn_gcdext (tmp_gp, tmp_sp, &tmp_ssize, tmp_ap, asize, tmp_bp, bsize); + + ssize = ABS (tmp_ssize); + tmp_ssize = SIZ (a) >= 0 ? tmp_ssize : -tmp_ssize; + + if (t != NULL) + { + mpz_t x; + mpz_t gtmp, stmp; + + PTR (gtmp) = tmp_gp; + SIZ (gtmp) = gsize; + + PTR (stmp) = tmp_sp; + SIZ (stmp) = tmp_ssize; + + ASSERT (ssize <= bsize); /* ssize*2 + asize + 1 <= asize + bsize*2 + 1 */ + PTR (x) = tmp_sp + ssize; + ALLOC (x) = ssize + asize + 1; + + mpz_mul (x, stmp, a); + mpz_sub (x, gtmp, x); + mpz_divexact (t, x, b); + } + + if (s != NULL) + { + mp_ptr sp; + + sp = MPZ_NEWALLOC (s, ssize); + MPN_COPY (sp, tmp_sp, ssize); + SIZ (s) = tmp_ssize; + } + + if (g != NULL) + { + gp = MPZ_NEWALLOC (g, gsize); + MPN_COPY (gp, tmp_gp, gsize); + SIZ (g) = gsize; + } + + TMP_FREE; +} -- cgit v1.2.3