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/lcm.c b/third_party/gmp/mpz/lcm.c
new file mode 100644
index 0000000..2807ef7
--- /dev/null
+++ b/third_party/gmp/mpz/lcm.c
@@ -0,0 +1,87 @@
+/* mpz_lcm -- mpz/mpz least common multiple.
+
+Copyright 1996, 2000, 2001, 2005, 2012 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"
+
+void
+mpz_lcm (mpz_ptr r, mpz_srcptr u, mpz_srcptr v)
+{
+ mpz_t g;
+ mp_size_t usize, vsize;
+ TMP_DECL;
+
+ usize = SIZ (u);
+ vsize = SIZ (v);
+ if (usize == 0 || vsize == 0)
+ {
+ SIZ (r) = 0;
+ return;
+ }
+ usize = ABS (usize);
+ vsize = ABS (vsize);
+
+ if (vsize == 1 || usize == 1)
+ {
+ mp_limb_t vl, gl, c;
+ mp_srcptr up;
+ mp_ptr rp;
+
+ if (usize == 1)
+ {
+ usize = vsize;
+ MPZ_SRCPTR_SWAP (u, v);
+ }
+
+ MPZ_REALLOC (r, usize+1);
+
+ up = PTR(u);
+ vl = PTR(v)[0];
+ gl = mpn_gcd_1 (up, usize, vl);
+ vl /= gl;
+
+ rp = PTR(r);
+ c = mpn_mul_1 (rp, up, usize, vl);
+ rp[usize] = c;
+ usize += (c != 0);
+ SIZ(r) = usize;
+ return;
+ }
+
+ TMP_MARK;
+ MPZ_TMP_INIT (g, usize); /* v != 0 implies |gcd(u,v)| <= |u| */
+
+ mpz_gcd (g, u, v);
+ mpz_divexact (g, u, g);
+ mpz_mul (r, g, v);
+
+ SIZ (r) = ABS (SIZ (r)); /* result always positive */
+
+ TMP_FREE;
+}