add memory copying functions

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

1 files changed, 60 insertions, 0 deletions

diff --git a/src/string/memmove.c b/src/string/memmove.c
new file mode 100644
index 0000000..c721609
--- /dev/null
+++ b/src/string/memmove.c
@@ -0,0 +1,60 @@
+/**
+ * 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>
+
+
+
+/**
+ * Copy a memory segment to another, possibly overlapping, segment.
+ * 
+ * @param   whither  The destination memory segment.
+ * @param   whence   The source memory segment.
+ * @param   size     The number of bytes to copy.
+ * @return           `whither` is returned.
+ */
+void* memmove(void* whither, const void* whence, size_t size)
+{
+  /* TODO improve implementation of memcpy */
+  char* d = whither;
+  const char* s = whence;
+  if ((size_t)(d - s) < size)
+    while (size--)
+      d[size] = s[size];
+  else
+    while (size--)
+      *d++ = *s++;
+  return whither;
+}
+
+
+/**
+ * Copy a memory segment to another, possibly overlapping, segment.
+ * 
+ * This is a slibc extension added for completeness.
+ * It is only available if GNU extensions are available.
+ * 
+ * @param   whither  The destination memory segment.
+ * @param   whence   The source memory segment.
+ * @param   size     The number of bytes to copy.
+ * @return           `whither + size` is returned.
+ */
+void* mempmove(void* whither, const void* whence, size_t size)
+{
+  return (char*)memmove(whither, whence, size) + size;
+}
+