From 11da511c784eca003deb90c23570f0873954e0de Mon Sep 17 00:00:00 2001
From: Duncan Wilkie <antigravityd@gmail.com>
Date: Sat, 18 Nov 2023 06:11:09 -0600
Subject: Initial commit.

---
 gmp-6.3.0/mpn/generic/binvert.c | 106 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 gmp-6.3.0/mpn/generic/binvert.c

(limited to 'gmp-6.3.0/mpn/generic/binvert.c')

diff --git a/gmp-6.3.0/mpn/generic/binvert.c b/gmp-6.3.0/mpn/generic/binvert.c
new file mode 100644
index 0000000..a170e66
--- /dev/null
+++ b/gmp-6.3.0/mpn/generic/binvert.c
@@ -0,0 +1,106 @@
+/* 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, 2021 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);
+      /* Only the values in the range xp + rn .. xp + newrn - 1 are
+	 used by the _mullo_n below.
+	 Since m >= newrn, we do not need the following. */
+      /* 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);
+    }
+}
-- 
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