add memfrob

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/src/string/memfrob.c b/src/string/memfrob.c
new file mode 100644
index 0000000..e43496a
--- /dev/null
+++ b/src/string/memfrob.c
@@ -0,0 +1,39 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.
+ */
+#include <string.h>
+#include <stddef.h>
+
+
+
+/**
+ * Performs an inplace bitwise XOR:ing of
+ * a memory segment. The pattern is 00101010.
+ * 
+ * This is a GNU extension.
+ * 
+ * @param   segment  The memory segment.
+ * @param   size     The size of the memory segment.
+ * @return           `segment` is returned
+ */
+char* memfrob(char* segment, size_t size)
+{
+  while (--size)
+    segment[size] ^= 0x2A;
+  return segment;
+}
+