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/gcd_1.c | 103 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 gmp-6.3.0/mpn/generic/gcd_1.c

(limited to 'gmp-6.3.0/mpn/generic/gcd_1.c')

diff --git a/gmp-6.3.0/mpn/generic/gcd_1.c b/gmp-6.3.0/mpn/generic/gcd_1.c
new file mode 100644
index 0000000..22b1422
--- /dev/null
+++ b/gmp-6.3.0/mpn/generic/gcd_1.c
@@ -0,0 +1,103 @@
+/* mpn_gcd_1 -- mpn and limb greatest common divisor.
+
+Copyright 1994, 1996, 2000, 2001, 2009, 2012, 2019 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"
+#include "longlong.h"
+
+/* Does not work for U == 0 or V == 0.  It would be tough to make it work for
+   V == 0 since gcd(x,0) = x, and U does not generally fit in an mp_limb_t.
+
+   The threshold for doing u%v when size==1 will vary by CPU according to
+   the speed of a division and the code generated for the main loop.  Any
+   tuning for this is left to a CPU specific implementation.  */
+
+mp_limb_t
+mpn_gcd_1 (mp_srcptr up, mp_size_t size, mp_limb_t vlimb)
+{
+  mp_limb_t      ulimb;
+  unsigned long  zero_bits, u_low_zero_bits;
+  int c;
+
+  ASSERT (size >= 1);
+  ASSERT (vlimb != 0);
+  ASSERT_MPN_NONZERO_P (up, size);
+
+  ulimb = up[0];
+
+  /* Need vlimb odd for modexact, want it odd to get common zeros. */
+  count_trailing_zeros (zero_bits, vlimb);
+  vlimb >>= zero_bits;
+
+  if (size > 1)
+    {
+      /* Must get common zeros before the mod reduction.  If ulimb==0 then
+	 vlimb already gives the common zeros.  */
+      if (ulimb != 0)
+	{
+	  count_trailing_zeros (u_low_zero_bits, ulimb);
+	  zero_bits = MIN (zero_bits, u_low_zero_bits);
+	}
+
+      ulimb = MPN_MOD_OR_MODEXACT_1_ODD (up, size, vlimb);
+      if (ulimb == 0)
+	goto done;
+
+      count_trailing_zeros (c, ulimb);
+      ulimb >>= c;
+    }
+  else
+    {
+      /* size==1, so up[0]!=0 */
+      count_trailing_zeros (u_low_zero_bits, ulimb);
+      ulimb >>= u_low_zero_bits;
+      zero_bits = MIN (zero_bits, u_low_zero_bits);
+
+      /* make u bigger */
+      if (vlimb > ulimb)
+	MP_LIMB_T_SWAP (ulimb, vlimb);
+
+      /* if u is much bigger than v, reduce using a division rather than
+	 chipping away at it bit-by-bit */
+      if ((ulimb >> 16) > vlimb)
+	{
+	  ulimb %= vlimb;
+	  if (ulimb == 0)
+	    goto done;
+
+	  count_trailing_zeros (c, ulimb);
+	  ulimb >>= c;
+	}
+    }
+
+  vlimb = mpn_gcd_11 (ulimb, vlimb);
+
+ done:
+  return vlimb << zero_bits;
+}
-- 
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