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/mpf/reldiff.c b/third_party/gmp/mpf/reldiff.c
new file mode 100644
index 0000000..81f05dd
--- /dev/null
+++ b/third_party/gmp/mpf/reldiff.c
@@ -0,0 +1,64 @@
+/* mpf_reldiff -- Generate the relative difference of two floats.
+
+Copyright 1996, 2001, 2004, 2005 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"
+
+
+/* The precision we use for d = x-y is based on what mpf_div will want from
+ the dividend. It calls mpn_div_q to produce a quotient of rprec+1 limbs.
+ So rprec+1 == dsize - xsize + 1, hence dprec = rprec+xsize. */
+
+void
+mpf_reldiff (mpf_t rdiff, mpf_srcptr x, mpf_srcptr y)
+{
+ if (UNLIKELY (SIZ(x) == 0))
+ {
+ mpf_set_ui (rdiff, (unsigned long int) (mpf_sgn (y) != 0));
+ }
+ else
+ {
+ mp_size_t dprec;
+ mpf_t d;
+ TMP_DECL;
+
+ TMP_MARK;
+ dprec = PREC(rdiff) + ABSIZ(x);
+ ASSERT (PREC(rdiff)+1 == dprec - ABSIZ(x) + 1);
+
+ PREC(d) = dprec;
+ PTR(d) = TMP_ALLOC_LIMBS (dprec + 1);
+
+ mpf_sub (d, x, y);
+ SIZ(d) = ABSIZ(d);
+ mpf_div (rdiff, d, x);
+
+ TMP_FREE;
+ }
+}