Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpn / cray / ieee / submul_1.c

diff --git a/gmp/mpn/cray/ieee/submul_1.c b/gmp/mpn/cray/ieee/submul_1.c
new file mode 100644 (file)
index 0000000..4d7a6b4
--- /dev/null
+++ b/gmp/mpn/cray/ieee/submul_1.c
@@ -0,0 +1,101 @@
+/* Cray PVP/IEEE mpn_submul_1 -- multiply a limb vector with a limb and
+   subtract the result from a second limb vector.
+
+Copyright 2000, 2001, 2002 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 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.
+
+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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
+
+/* This code runs at just under 9 cycles/limb on a T90.  That is not perfect,
+   mainly due to vector register shortage in the main loop.  Assembly code
+   should bring it down to perhaps 7 cycles/limb.  */
+
+#include <intrinsics.h>
+#include "gmp.h"
+#include "gmp-impl.h"
+
+mp_limb_t
+mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl)
+{
+  mp_limb_t cy[n];
+  mp_limb_t a, b, r, s0, s1, c0, c1;
+  mp_size_t i;
+  int more_carries;
+
+  if (up == rp)
+    {
+      /* The algorithm used below cannot handle overlap.  Handle it here by
+        making a temporary copy of the source vector, then call ourselves.  */
+      mp_limb_t xp[n];
+      MPN_COPY (xp, up, n);
+      return mpn_submul_1 (rp, xp, n, vl);
+    }
+
+  a = up[0] * vl;
+  r = rp[0];
+  s0 = r - a;
+  rp[0] = s0;
+  c1 = ((s0 & a) | ((s0 | a) & ~r)) >> 63;
+  cy[0] = c1;
+
+  /* Main multiply loop.  Generate a raw accumulated output product in rp[]
+     and a carry vector in cy[].  */
+#pragma _CRI ivdep
+  for (i = 1; i < n; i++)
+    {
+      a = up[i] * vl;
+      b = _int_mult_upper (up[i - 1], vl);
+      s0 = a + b;
+      c0 = ((a & b) | ((a | b) & ~s0)) >> 63;
+      r = rp[i];
+      s1 = r - s0;
+      rp[i] = s1;
+      c1 = ((s1 & s0) | ((s1 | s0) & ~r)) >> 63;
+      cy[i] = c0 + c1;
+    }
+  /* Carry subtract loop.  Subtract the carry vector cy[] from the raw result
+     rp[] and store the new result back to rp[].  */
+  more_carries = 0;
+#pragma _CRI ivdep
+  for (i = 1; i < n; i++)
+    {
+      r = rp[i];
+      c0 = cy[i - 1];
+      s0 = r - c0;
+      rp[i] = s0;
+      c0 = (s0 & ~r) >> 63;
+      more_carries += c0;
+    }
+  /* If that second loop generated carry, handle that in scalar loop.  */
+  if (more_carries)
+    {
+      mp_limb_t cyrec = 0;
+      /* Look for places where rp[k] == ~0 and cy[k-1] == 1 or
+        rp[k] == ~1 and cy[k-1] == 2.
+        These are where we got a recurrency carry.  */
+      for (i = 1; i < n; i++)
+       {
+         r = rp[i];
+         c0 = ~r < cy[i - 1];
+         s0 = r - cyrec;
+         rp[i] = s0;
+         c1 = (s0 & ~r) >> 63;
+         cyrec = c0 | c1;
+       }
+      return _int_mult_upper (up[n - 1], vl) + cyrec + cy[n - 1];
+    }
+
+  return _int_mult_upper (up[n - 1], vl) + cy[n - 1];
+}