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/div.c b/third_party/gmp/mpf/div.c
new file mode 100644
index 0000000..d13af75
--- /dev/null
+++ b/third_party/gmp/mpf/div.c
@@ -0,0 +1,137 @@
+/* mpf_div -- Divide two floats.
+
+Copyright 1993, 1994, 1996, 2000-2002, 2004, 2005, 2010, 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"
+
+
+/* Not done:
+
+ No attempt is made to identify an overlap u==v. The result will be
+ correct (1.0), but a full actual division is done whereas of course
+ x/x==1 needs no work. Such a call is not a sensible thing to make, and
+ it's left to an application to notice and optimize if it might arise
+ somehow through pointer aliasing or whatever.
+
+ Enhancements:
+
+ The high quotient limb is non-zero when high{up,vsize} >= {vp,vsize}. We
+ could make that comparison and use qsize==prec instead of qsize==prec+1,
+ to save one limb in the division.
+
+ If r==u but the size is enough bigger than prec that there won't be an
+ overlap between quotient and dividend in mpn_div_q, then we can avoid
+ copying up,usize. This would only arise from a prec reduced with
+ mpf_set_prec_raw and will be pretty unusual, but might be worthwhile if
+ it could be worked into the copy_u decision cleanly. */
+
+void
+mpf_div (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
+{
+ mp_srcptr up, vp;
+ mp_ptr rp, tp, new_vp;
+ mp_size_t usize, vsize, rsize, prospective_rsize, tsize, zeros;
+ mp_size_t sign_quotient, prec, high_zero, chop;
+ mp_exp_t rexp;
+ int copy_u;
+ TMP_DECL;
+
+ usize = SIZ(u);
+ vsize = SIZ(v);
+
+ if (UNLIKELY (vsize == 0))
+ DIVIDE_BY_ZERO;
+
+ if (usize == 0)
+ {
+ SIZ(r) = 0;
+ EXP(r) = 0;
+ return;
+ }
+
+ sign_quotient = usize ^ vsize;
+ usize = ABS (usize);
+ vsize = ABS (vsize);
+ prec = PREC(r);
+
+ TMP_MARK;
+ rexp = EXP(u) - EXP(v) + 1;
+
+ rp = PTR(r);
+ up = PTR(u);
+ vp = PTR(v);
+
+ prospective_rsize = usize - vsize + 1; /* quot from using given u,v sizes */
+ rsize = prec + 1; /* desired quot */
+
+ zeros = rsize - prospective_rsize; /* padding u to give rsize */
+ copy_u = (zeros > 0 || rp == up); /* copy u if overlap or padding */
+
+ chop = MAX (-zeros, 0); /* negative zeros means shorten u */
+ up += chop;
+ usize -= chop;
+ zeros += chop; /* now zeros >= 0 */
+
+ tsize = usize + zeros; /* size for possible copy of u */
+
+ /* copy and possibly extend u if necessary */
+ if (copy_u)
+ {
+ tp = TMP_ALLOC_LIMBS (tsize + 1); /* +1 for mpn_div_q's scratch needs */
+ MPN_ZERO (tp, zeros);
+ MPN_COPY (tp+zeros, up, usize);
+ up = tp;
+ usize = tsize;
+ }
+ else
+ {
+ tp = TMP_ALLOC_LIMBS (usize + 1);
+ }
+
+ /* ensure divisor doesn't overlap quotient */
+ if (rp == vp)
+ {
+ new_vp = TMP_ALLOC_LIMBS (vsize);
+ MPN_COPY (new_vp, vp, vsize);
+ vp = new_vp;
+ }
+
+ ASSERT (usize-vsize+1 == rsize);
+ mpn_div_q (rp, up, usize, vp, vsize, tp);
+
+ /* strip possible zero high limb */
+ high_zero = (rp[rsize-1] == 0);
+ rsize -= high_zero;
+ rexp -= high_zero;
+
+ SIZ(r) = sign_quotient >= 0 ? rsize : -rsize;
+ EXP(r) = rexp;
+ TMP_FREE;
+}