Revert "Remove gmp from AOS"

This reverts commit f37c97684f0910a3f241394549392f00145ab0f7.

We need gmp for SymEngine for symbolicmanipultion in C++

Change-Id: Ia13216d1715cf96944f7b4f422b7a799f921d4a4
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/third_party/gmp/mpz/xor.c b/third_party/gmp/mpz/xor.c
new file mode 100644
index 0000000..5ec657a
--- /dev/null
+++ b/third_party/gmp/mpz/xor.c
@@ -0,0 +1,146 @@
+/* mpz_xor -- Logical xor.
+
+Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2005, 2012,
+2015-2018 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_xor (mpz_ptr res, mpz_srcptr op1, mpz_srcptr op2)
+{
+  mp_srcptr op1_ptr, op2_ptr;
+  mp_size_t op1_size, op2_size;
+  mp_ptr res_ptr;
+  mp_size_t res_size;
+
+  op1_size = SIZ(op1);
+  op2_size = SIZ(op2);
+
+  if (op1_size < op2_size)
+    {
+      MPZ_SRCPTR_SWAP (op1, op2);
+      MP_SIZE_T_SWAP (op1_size, op2_size);
+    }
+
+  op1_ptr = PTR(op1);
+  res_ptr = PTR(res);
+
+  if (op2_size >= 0)
+    {
+      if (res_ptr != op1_ptr)
+	{
+	  res_ptr = MPZ_REALLOC (res, op1_size);
+	  MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size,
+		    op1_size - op2_size);
+	}
+      if (LIKELY (op2_size != 0))
+	mpn_xor_n (res_ptr, op1_ptr, PTR(op2), op2_size);
+      res_size = op1_size;
+
+      MPN_NORMALIZE (res_ptr, res_size);
+      SIZ(res) = res_size;
+    }
+  else
+    {
+      mp_ptr opx;
+      TMP_DECL;
+
+      op2_size = -op2_size;
+      TMP_MARK;
+      if (op1_size < 0)
+	{
+	  mp_ptr opy;
+
+	  /* Both operands are negative, the result will be positive.
+	      (-OP1) ^ (-OP2) =
+	     = ~(OP1 - 1) ^ ~(OP2 - 1) =
+	     = (OP1 - 1) ^ (OP2 - 1)  */
+
+	  op1_size = -op1_size;
+
+	  /* Possible optimization: Decrease mpn_sub precision,
+	     as we won't use the entire res of both.  */
+	  TMP_ALLOC_LIMBS_2 (opx, op1_size, opy, op2_size);
+	  mpn_sub_1 (opx, op1_ptr, op1_size, (mp_limb_t) 1);
+	  op1_ptr = opx;
+
+	  mpn_sub_1 (opy, PTR(op2), op2_size, (mp_limb_t) 1);
+	  op2_ptr = opy;
+
+	  res_ptr = MPZ_NEWALLOC (res, op2_size);
+	  /* Don't re-read OP1_PTR and OP2_PTR.  They point to temporary
+	     space--never to the space PTR(res) used to point to before
+	     reallocation.  */
+
+	  MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size,
+		    op2_size - op1_size);
+	  mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op1_size);
+	  TMP_FREE;
+	  res_size = op2_size;
+
+	  MPN_NORMALIZE (res_ptr, res_size);
+	  SIZ(res) = res_size;
+	}
+      else
+	{
+	  /* Operand 2 negative, so will be the result.
+	     -(OP1 ^ (-OP2)) = -(OP1 ^ ~(OP2 - 1)) =
+	     = ~(OP1 ^ ~(OP2 - 1)) + 1 =
+	     = (OP1 ^ (OP2 - 1)) + 1      */
+
+	  res_size = MAX (op1_size, op2_size);
+	  res_ptr = MPZ_REALLOC (res, res_size + 1);
+	  op1_ptr = PTR(op1);
+
+	  opx = TMP_ALLOC_LIMBS (op2_size);
+	  mpn_sub_1 (opx, PTR(op2), op2_size, (mp_limb_t) 1);
+	  op2_ptr = opx;
+
+	  if (res_size == op1_size)
+	    {
+	      MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, op1_size - op2_size);
+	      mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op2_size);
+	    }
+	  else
+	    {
+	      MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size, op2_size - op1_size);
+	      if (LIKELY (op1_size != 0))
+		mpn_xor_n (res_ptr, op1_ptr, op2_ptr, op1_size);
+	    }
+	  TMP_FREE;
+
+	  res_ptr[res_size] = 0;
+	  MPN_INCR_U (res_ptr, res_size + 1, (mp_limb_t) 1);
+	  res_size += res_ptr[res_size];
+
+	  MPN_NORMALIZE_NOT_ZERO (res_ptr, res_size);
+	  SIZ(res) = -res_size;
+	}
+    }
+}