Initial commit.

1 files changed, 131 insertions, 0 deletions

diff --git a/gmp-6.3.0/mpn/generic/gcd_22.c b/gmp-6.3.0/mpn/generic/gcd_22.c
new file mode 100644
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+++ b/gmp-6.3.0/mpn/generic/gcd_22.c
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+/* mpn_gcd_22 -- double 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"
+
+#if GMP_NAIL_BITS > 0
+#error Nails not supported.
+#endif
+
+mp_double_limb_t
+mpn_gcd_22 (mp_limb_t u1, mp_limb_t u0, mp_limb_t v1, mp_limb_t v0)
+{
+  mp_double_limb_t g;
+  ASSERT (u0 & v0 & 1);
+
+  /* Implicit least significant bit */
+  u0 = (u0 >> 1) | (u1 << (GMP_LIMB_BITS - 1));
+  u1 >>= 1;
+
+  v0 = (v0 >> 1) | (v1 << (GMP_LIMB_BITS - 1));
+  v1 >>= 1;
+
+  while (u1 || v1) /* u1 == 0 can happen at most twice per call */
+    {
+      mp_limb_t vgtu, t1, t0;
+      sub_ddmmss (t1, t0, u1, u0, v1, v0);
+      vgtu = LIMB_HIGHBIT_TO_MASK(t1);
+
+      if (UNLIKELY (t0 == 0))
+	{
+	  if (t1 == 0)
+	    {
+	      g.d1 = (u1 << 1) | (u0 >> (GMP_LIMB_BITS - 1));
+	      g.d0 = (u0 << 1) | 1;
+	      return g;
+	    }
+	  int c;
+	  count_trailing_zeros (c, t1);
+
+	  /* v1 = min (u1, v1) */
+	  v1 += (vgtu & t1);
+	  /* u0 = |u1 - v1| */
+	  u0 = (t1 ^ vgtu) - vgtu;
+	  ASSERT (c < GMP_LIMB_BITS - 1);
+	  u0 >>= c + 1;
+	  u1 = 0;
+	}
+      else
+	{
+	  int c;
+	  count_trailing_zeros (c, t0);
+	  c++;
+	  /* V <-- min (U, V).
+
+	     Assembly version should use cmov. Another alternative,
+	     avoiding carry propagation, would be
+
+	     v0 += vgtu & t0; v1 += vtgu & (u1 - v1);
+	  */
+	  add_ssaaaa (v1, v0, v1, v0, vgtu & t1, vgtu & t0);
+	  /* U  <--  |U - V|
+	     No carry handling needed in this conditional negation,
+	     since t0 != 0. */
+	  u0 = (t0 ^ vgtu) - vgtu;
+	  u1 = t1 ^ vgtu;
+	  if (UNLIKELY (c == GMP_LIMB_BITS))
+	    {
+	      u0 = u1;
+	      u1 = 0;
+	    }
+	  else
+	    {
+	      u0 = (u0 >> c) | (u1 << (GMP_LIMB_BITS - c));
+	      u1 >>= c;
+	    }
+	}
+    }
+  while ((v0 | u0) & GMP_LIMB_HIGHBIT)
+    { /* At most two iterations */
+      mp_limb_t vgtu, t0;
+      int c;
+      sub_ddmmss (vgtu, t0, 0, u0, 0, v0);
+      if (UNLIKELY (t0 == 0))
+	{
+	  g.d1 = u0 >> (GMP_LIMB_BITS - 1);
+	  g.d0 = (u0 << 1) | 1;
+	  return g;
+	}
+
+      /* v <-- min (u, v) */
+      v0 += (vgtu & t0);
+
+      /* u <-- |u - v| */
+      u0 = (t0 ^ vgtu) - vgtu;
+
+      count_trailing_zeros (c, t0);
+      u0 = (u0 >> 1) >> c;
+    }
+
+  g.d0 = mpn_gcd_11 ((u0 << 1) + 1, (v0 << 1) + 1);
+  g.d1 = 0;
+  return g;
+}