Add libgmp 6.2.0 to third_party
Don't build it yet. That will come in the next review.
Change-Id: Idf3266558165e5ab45f4a41c98cc8c838c8244d5
diff --git a/third_party/gmp/mpz/gcd.c b/third_party/gmp/mpz/gcd.c
new file mode 100644
index 0000000..9557155
--- /dev/null
+++ b/third_party/gmp/mpz/gcd.c
@@ -0,0 +1,164 @@
+/* mpz/gcd.c: Calculate the greatest common divisor of two integers.
+
+Copyright 1991, 1993, 1994, 1996, 2000-2002, 2005, 2010, 2015, 2016
+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 "gmp-impl.h"
+#include "longlong.h"
+
+
+void
+mpz_gcd (mpz_ptr g, mpz_srcptr u, mpz_srcptr v)
+{
+ unsigned long int g_zero_bits, u_zero_bits, v_zero_bits;
+ mp_size_t g_zero_limbs, u_zero_limbs, v_zero_limbs;
+ mp_ptr tp;
+ mp_ptr up;
+ mp_size_t usize;
+ mp_ptr vp;
+ mp_size_t vsize;
+ mp_size_t gsize;
+ TMP_DECL;
+
+ up = PTR(u);
+ usize = ABSIZ (u);
+ vp = PTR(v);
+ vsize = ABSIZ (v);
+ /* GCD(0, V) == V. */
+ if (usize == 0)
+ {
+ SIZ (g) = vsize;
+ if (g == v)
+ return;
+ tp = MPZ_NEWALLOC (g, vsize);
+ MPN_COPY (tp, vp, vsize);
+ return;
+ }
+
+ /* GCD(U, 0) == U. */
+ if (vsize == 0)
+ {
+ SIZ (g) = usize;
+ if (g == u)
+ return;
+ tp = MPZ_NEWALLOC (g, usize);
+ MPN_COPY (tp, up, usize);
+ return;
+ }
+
+ if (usize == 1)
+ {
+ SIZ (g) = 1;
+ MPZ_NEWALLOC (g, 1)[0] = mpn_gcd_1 (vp, vsize, up[0]);
+ return;
+ }
+
+ if (vsize == 1)
+ {
+ SIZ(g) = 1;
+ MPZ_NEWALLOC (g, 1)[0] = mpn_gcd_1 (up, usize, vp[0]);
+ return;
+ }
+
+ TMP_MARK;
+
+ /* Eliminate low zero bits from U and V and move to temporary storage. */
+ tp = up;
+ while (*tp == 0)
+ tp++;
+ u_zero_limbs = tp - up;
+ usize -= u_zero_limbs;
+ count_trailing_zeros (u_zero_bits, *tp);
+ up = TMP_ALLOC_LIMBS (usize);
+ if (u_zero_bits != 0)
+ {
+ mpn_rshift (up, tp, usize, u_zero_bits);
+ usize -= up[usize - 1] == 0;
+ }
+ else
+ MPN_COPY (up, tp, usize);
+
+ tp = vp;
+ while (*tp == 0)
+ tp++;
+ v_zero_limbs = tp - vp;
+ vsize -= v_zero_limbs;
+ count_trailing_zeros (v_zero_bits, *tp);
+ vp = TMP_ALLOC_LIMBS (vsize);
+ if (v_zero_bits != 0)
+ {
+ mpn_rshift (vp, tp, vsize, v_zero_bits);
+ vsize -= vp[vsize - 1] == 0;
+ }
+ else
+ MPN_COPY (vp, tp, vsize);
+
+ if (u_zero_limbs > v_zero_limbs)
+ {
+ g_zero_limbs = v_zero_limbs;
+ g_zero_bits = v_zero_bits;
+ }
+ else
+ {
+ g_zero_limbs = u_zero_limbs;
+ if (u_zero_limbs < v_zero_limbs)
+ g_zero_bits = u_zero_bits;
+ else /* Equal. */
+ g_zero_bits = MIN (u_zero_bits, v_zero_bits);
+ }
+
+ /* Call mpn_gcd. The 2nd argument must not have more bits than the 1st. */
+ vsize = (usize < vsize || (usize == vsize && up[usize-1] < vp[vsize-1]))
+ ? mpn_gcd (vp, vp, vsize, up, usize)
+ : mpn_gcd (vp, up, usize, vp, vsize);
+
+ /* Here G <-- V << (g_zero_limbs*GMP_LIMB_BITS + g_zero_bits). */
+ gsize = vsize + g_zero_limbs;
+ if (g_zero_bits != 0)
+ {
+ mp_limb_t cy_limb;
+ gsize += (vp[vsize - 1] >> (GMP_NUMB_BITS - g_zero_bits)) != 0;
+ tp = MPZ_NEWALLOC (g, gsize);
+ MPN_ZERO (tp, g_zero_limbs);
+
+ tp = tp + g_zero_limbs;
+ cy_limb = mpn_lshift (tp, vp, vsize, g_zero_bits);
+ if (cy_limb != 0)
+ tp[vsize] = cy_limb;
+ }
+ else
+ {
+ tp = MPZ_NEWALLOC (g, gsize);
+ MPN_ZERO (tp, g_zero_limbs);
+ MPN_COPY (tp + g_zero_limbs, vp, vsize);
+ }
+
+ SIZ (g) = gsize;
+ TMP_FREE;
+}