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/cray/sub_n.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 gmp-6.3.0/mpn/cray/sub_n.c

(limited to 'gmp-6.3.0/mpn/cray/sub_n.c')

diff --git a/gmp-6.3.0/mpn/cray/sub_n.c b/gmp-6.3.0/mpn/cray/sub_n.c
new file mode 100644
index 0000000..f518764
--- /dev/null
+++ b/gmp-6.3.0/mpn/cray/sub_n.c
@@ -0,0 +1,90 @@
+/* Cray PVP mpn_sub_n -- subtract two limb vectors and store their difference
+   in a third limb vector.
+
+Copyright 1996, 2000, 2001 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/.  */
+
+/* This code runs at 4 cycles/limb.  It may be possible to bring it down
+   to 3 cycles/limb.  */
+
+#include "gmp-impl.h"
+
+mp_limb_t
+mpn_sub_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
+{
+  mp_limb_t cy[n];
+  mp_limb_t a, b, r, s0, c0, c1;
+  mp_size_t i;
+  int more_carries;
+
+  /* Main subtract loop.  Generate a raw output difference in rp[] and a
+     borrow vector in cy[].  */
+#pragma _CRI ivdep
+  for (i = 0; i < n; i++)
+    {
+      a = up[i];
+      b = vp[i];
+      s0 = a - b;		/* a = s0 + b */
+      rp[i] = s0;
+      c0 = ((s0 & b) | ((s0 | b) & ~a)) >> 63;
+      cy[i] = c0;
+    }
+  /* Borrow subtract loop.  Subtract the borrow vector cy[] from the raw
+     difference rp[] and store the new difference back to rp[0].  If this
+     generates further borrow, set more_carries.  */
+  more_carries = 0;
+#pragma _CRI ivdep
+  for (i = 1; i < n; i++)
+    {
+      r = rp[i];
+      c0 = cy[i - 1];
+      s0 = r - c0;		/* r = s0 + c0 */
+      rp[i] = s0;
+      c0 = (s0 & ~r) >> 63;
+      more_carries += c0;
+    }
+  /* If that second loop generated borrow, handle that in scalar loop.  */
+  if (more_carries)
+    {
+      mp_limb_t cyrec = 0;
+      /* Look for places where rp[k] contains just ones and cy[k-1] is
+	 non-zero.  These are where we got a recurrency borrow.  */
+      for (i = 1; i < n; i++)
+	{
+	  r = rp[i];
+	  c0 = (~r == 0 && cy[i - 1] != 0);
+	  s0 = r - cyrec;
+	  rp[i] = s0;
+	  c1 = (s0 & ~r) >> 63;
+	  cyrec = c0 | c1;
+	}
+      return cyrec | cy[n - 1];
+    }
+
+  return cy[n - 1];
+}
-- 
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