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/mpn/generic/binvert.c b/third_party/gmp/mpn/generic/binvert.c
new file mode 100644
index 0000000..6c24ab7
--- /dev/null
+++ b/third_party/gmp/mpn/generic/binvert.c
@@ -0,0 +1,103 @@
+/* Compute {up,n}^(-1) mod B^n.
+
+ Contributed to the GNU project by Torbjorn Granlund.
+
+ THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH MUTABLE INTERFACES. IT IS ONLY
+ SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
+ GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE.
+
+Copyright (C) 2004-2007, 2009, 2012, 2017 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"
+
+
+/*
+ r[k+1] = r[k] - r[k] * (u*r[k] - 1)
+ r[k+1] = r[k] + r[k] - r[k]*(u*r[k])
+*/
+
+#if TUNE_PROGRAM_BUILD
+#define NPOWS \
+ ((sizeof(mp_size_t) > 6 ? 48 : 8*sizeof(mp_size_t)))
+#else
+#define NPOWS \
+ ((sizeof(mp_size_t) > 6 ? 48 : 8*sizeof(mp_size_t)) - LOG2C (BINV_NEWTON_THRESHOLD))
+#endif
+
+mp_size_t
+mpn_binvert_itch (mp_size_t n)
+{
+ mp_size_t itch_local = mpn_mulmod_bnm1_next_size (n);
+ mp_size_t itch_out = mpn_mulmod_bnm1_itch (itch_local, n, (n + 1) >> 1);
+ return itch_local + itch_out;
+}
+
+void
+mpn_binvert (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_ptr scratch)
+{
+ mp_ptr xp;
+ mp_size_t rn, newrn;
+ mp_size_t sizes[NPOWS], *sizp;
+ mp_limb_t di;
+
+ /* Compute the computation precisions from highest to lowest, leaving the
+ base case size in 'rn'. */
+ sizp = sizes;
+ for (rn = n; ABOVE_THRESHOLD (rn, BINV_NEWTON_THRESHOLD); rn = (rn + 1) >> 1)
+ *sizp++ = rn;
+
+ xp = scratch;
+
+ /* Compute a base value of rn limbs. */
+ MPN_ZERO (xp, rn);
+ xp[0] = 1;
+ binvert_limb (di, up[0]);
+ if (BELOW_THRESHOLD (rn, DC_BDIV_Q_THRESHOLD))
+ mpn_sbpi1_bdiv_q (rp, xp, rn, up, rn, -di);
+ else
+ mpn_dcpi1_bdiv_q (rp, xp, rn, up, rn, -di);
+
+ mpn_neg (rp, rp, rn);
+
+ /* Use Newton iterations to get the desired precision. */
+ for (; rn < n; rn = newrn)
+ {
+ mp_size_t m;
+ newrn = *--sizp;
+
+ /* X <- UR. */
+ m = mpn_mulmod_bnm1_next_size (newrn);
+ mpn_mulmod_bnm1 (xp, m, up, newrn, rp, rn, xp + m);
+ mpn_sub_1 (xp + m, xp, rn - (m - newrn), 1);
+
+ /* R = R(X/B^rn) */
+ mpn_mullo_n (rp + rn, rp, xp + rn, newrn - rn);
+ mpn_neg (rp + rn, rp + rn, newrn - rn);
+ }
+}