memxor

[Simon Josefsson]

Hi.  This is a helper module needed by the hmac-md5 crypto module that
I'll post after this.  What do you think?  Ok to install?

I am not sure about the prototype.  Should it use 'char*'?  'int*'?
The implementation XOR the data buffers char by char, but there is no
inherent requirement that it is done that way, so I thought the API
should use 'void*' similar to memcpy.

Thanks.

Index: m4/memxor.m4
===================================================================
RCS file: m4/memxor.m4
diff -N m4/memxor.m4
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ m4/memxor.m4        5 Oct 2005 12:07:36 -0000
@@ -0,0 +1,11 @@
+# memxor.m4 serial 1
+dnl Copyright (C) 2005 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_MEMXOR],
+[
+  AC_LIBSOURCES([memxor.h, memxor.c])
+  AC_LIBOBJ([memxor])
+])
Index: lib/memxor.h
===================================================================
RCS file: lib/memxor.h
diff -N lib/memxor.h
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ lib/memxor.h        5 Oct 2005 12:07:36 -0000
@@ -0,0 +1,28 @@
+/* memxor.h -- perform binary exclusive OR operation on memory blocks.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+   This program 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, or (at your option)
+   any later version.
+
+   This program 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.  */
+
+/* Written by Simon Josefsson.  The interface was inspired by memxor
+   in Niels Möller's Nettle. */
+
+#ifndef MEMXOR_H
+# define MEMXOR_H
+
+#include <stddef.h>
+
+void *memxor (void *dest, const void *src, size_t n);
+
+#endif /* MEMXOR_H */
Index: lib/memxor.c
===================================================================
RCS file: lib/memxor.c
diff -N lib/memxor.c
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ lib/memxor.c        5 Oct 2005 12:07:36 -0000
@@ -0,0 +1,38 @@
+/* memxor.c -- perform binary exclusive OR operation of two memory blocks.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+   This program 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, or (at your option)
+   any later version.
+
+   This program 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.  */
+
+/* Written by Simon Josefsson.  The interface was inspired by memxor
+   in Niels Möller's Nettle. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "memxor.h"
+
+void *
+memxor (void *dest, const void *src, size_t n)
+{
+  const char *s = src;
+  char *d = dest;
+  size_t i;
+
+  for (i = 0; i < n; i++)
+    d[i] ^= s[i];
+
+  return dest;
+}
Index: modules/memxor
===================================================================
RCS file: modules/memxor
diff -N modules/memxor
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ modules/memxor      5 Oct 2005 12:07:36 -0000
@@ -0,0 +1,23 @@
+Description:
+memxor() function: binary exclusive or operation on two memory blocks
+
+Files:
+lib/memxor.h
+lib/memxor.c
+m4/memxor.m4
+
+Depends-on:
+
+configure.ac:
+gl_MEMXOR
+
+Makefile.am:
+
+Include:
+"memxor.h"
+
+License:
+LGPL
+
+Maintainer:
+Simon Josefsson