2.5-18.1

1 files changed, 65 insertions, 0 deletions

diff --git a/stdlib/submul_1.c b/stdlib/submul_1.c
new file mode 100644
index 0000000000..3e7163a2a3
--- /dev/null
+++ b/stdlib/submul_1.c
@@ -0,0 +1,65 @@
+/* mpn_submul_1 -- multiply the S1_SIZE long limb vector pointed to by S1_PTR
+   by S2_LIMB, subtract the S1_SIZE least significant limbs of the product
+   from the limb vector pointed to by RES_PTR.  Return the most significant
+   limb of the product, adjusted for carry-out from the subtraction.
+
+Copyright (C) 1992, 1993, 1994, 1996, 2005 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 2.1 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; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#include <gmp.h>
+#include "gmp-impl.h"
+#include "longlong.h"
+
+mp_limb_t
+mpn_submul_1 (res_ptr, s1_ptr, s1_size, s2_limb)
+     register mp_ptr res_ptr;
+     register mp_srcptr s1_ptr;
+     mp_size_t s1_size;
+     register mp_limb_t s2_limb;
+{
+  register mp_limb_t cy_limb;
+  register mp_size_t j;
+  register mp_limb_t prod_high, prod_low;
+  register mp_limb_t x;
+
+  /* The loop counter and index J goes from -SIZE to -1.  This way
+     the loop becomes faster.  */
+  j = -s1_size;
+
+  /* Offset the base pointers to compensate for the negative indices.  */
+  res_ptr -= j;
+  s1_ptr -= j;
+
+  cy_limb = 0;
+  do
+    {
+      umul_ppmm (prod_high, prod_low, s1_ptr[j], s2_limb);
+
+      prod_low += cy_limb;
+      cy_limb = (prod_low < cy_limb) + prod_high;
+
+      x = res_ptr[j];
+      prod_low = x - prod_low;
+      cy_limb += (prod_low > x);
+      res_ptr[j] = prod_low;
+    }
+  while (++j != 0);
+
+  return cy_limb;
+}