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/mul_2exp.c b/third_party/gmp/mpz/mul_2exp.c
new file mode 100644
index 0000000..6144d0d
--- /dev/null
+++ b/third_party/gmp/mpz/mul_2exp.c
@@ -0,0 +1,72 @@
+/* mpz_mul_2exp -- Multiply a bignum by 2**CNT
+
+Copyright 1991, 1993, 1994, 1996, 2001, 2002, 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_mul_2exp (mpz_ptr r, mpz_srcptr u, mp_bitcnt_t cnt)
+{
+ mp_size_t un, rn;
+ mp_size_t limb_cnt;
+ mp_ptr rp;
+ mp_srcptr up;
+ mp_limb_t rlimb;
+
+ un = ABSIZ (u);
+ limb_cnt = cnt / GMP_NUMB_BITS;
+ rn = un + limb_cnt;
+
+ if (un == 0)
+ rn = 0;
+ else
+ {
+ rp = MPZ_REALLOC (r, rn + 1);
+ up = PTR(u);
+
+ cnt %= GMP_NUMB_BITS;
+ if (cnt != 0)
+ {
+ rlimb = mpn_lshift (rp + limb_cnt, up, un, cnt);
+ rp[rn] = rlimb;
+ rn += (rlimb != 0);
+ }
+ else
+ {
+ MPN_COPY_DECR (rp + limb_cnt, up, un);
+ }
+
+ /* Zero all whole limbs at low end. Do it here and not before calling
+ mpn_lshift, not to lose for U == R. */
+ MPN_ZERO (rp, limb_cnt);
+ }
+
+ SIZ(r) = SIZ(u) >= 0 ? rn : -rn;
+}