1 files changed, 66 insertions, 0 deletions
diff --git a/mpi/generic/mpih-add1.c b/mpi/generic/mpih-add1.c
new file mode 100644
index 0000000..ebcd132
--- /dev/null
+++ b/mpi/generic/mpih-add1.c
@@ -0,0 +1,66 @@
+/* mpihelp-add_1.c  -  MPI helper functions
+ * Copyright (C) 1994, 1996, 1997, 1998, 
+ *               2000 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of 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.
+ *
+ * GnuPG 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 a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ *	 Actually it's the same code with only minor changes in the
+ *	 way the data is stored; this is to support the abstraction
+ *	 of an optional secure memory allocation which may be used
+ *	 to avoid revealing of sensitive data due to paging etc.
+ *	 The GNU MP Library itself is published under the LGPL;
+ *	 however I decided to publish this code under the plain GPL.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi-internal.h"
+#include "longlong.h"
+
+mpi_limb_t
+mpihelp_add_n( mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
+	       mpi_ptr_t s2_ptr, mpi_size_t size)
+{
+    mpi_limb_t x, y, cy;
+    mpi_size_t j;
+
+    /* The loop counter and index J goes from -SIZE to -1.  This way
+       the loop becomes faster.  */
+    j = -size;
+
+    /* Offset the base pointers to compensate for the negative indices. */
+    s1_ptr -= j;
+    s2_ptr -= j;
+    res_ptr -= j;
+
+    cy = 0;
+    do {
+	y = s2_ptr[j];
+	x = s1_ptr[j];
+	y += cy;		  /* add previous carry to one addend */
+	cy = y < cy;		  /* get out carry from that addition */
+	y += x; 		  /* add other addend */
+	cy += y < x;		  /* get out carry from that add, combine */
+	res_ptr[j] = y;
+    } while( ++j );
+
+    return cy;
+}
+