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/mpz/invert.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 gmp-6.3.0/mpz/invert.c

(limited to 'gmp-6.3.0/mpz/invert.c')

diff --git a/gmp-6.3.0/mpz/invert.c b/gmp-6.3.0/mpz/invert.c
new file mode 100644
index 0000000..5532d13
--- /dev/null
+++ b/gmp-6.3.0/mpz/invert.c
@@ -0,0 +1,72 @@
+/* mpz_invert (inv, x, n).  Find multiplicative inverse of X in Z(N).
+   If X has an inverse, return non-zero and store inverse in INVERSE,
+   otherwise, return 0 and put garbage in INVERSE.
+
+Copyright 1996-2001, 2005, 2012, 2014 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"
+
+int
+mpz_invert (mpz_ptr inverse, mpz_srcptr x, mpz_srcptr n)
+{
+  mpz_t gcd, tmp;
+  mp_size_t xsize, nsize, size;
+  TMP_DECL;
+
+  xsize = ABSIZ (x);
+  nsize = ABSIZ (n);
+
+  size = MAX (xsize, nsize) + 1;
+  TMP_MARK;
+
+  MPZ_TMP_INIT (gcd, size);
+  MPZ_TMP_INIT (tmp, size);
+  mpz_gcdext (gcd, tmp, (mpz_ptr) 0, x, n);
+
+  /* If no inverse existed, return with an indication of that.  */
+  if (!MPZ_EQUAL_1_P (gcd))
+    {
+      TMP_FREE;
+      return 0;
+    }
+
+  /* Make sure we return a positive inverse.  */
+  if (SIZ (tmp) < 0)
+    {
+      if (SIZ (n) < 0)
+	mpz_sub (inverse, tmp, n);
+      else
+	mpz_add (inverse, tmp, n);
+    }
+  else
+    mpz_set (inverse, tmp);
+
+  TMP_FREE;
+  return 1;
+}
-- 
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