1 files changed, 113 insertions, 0 deletions
diff --git a/erts/emulator/beam/elib_memmove.c b/erts/emulator/beam/elib_memmove.c
new file mode 100644
index 0000000000..d2fe8649ed
--- /dev/null
+++ b/erts/emulator/beam/elib_memmove.c
@@ -0,0 +1,113 @@
+/*
+ * %CopyrightBegin%
+ * 
+ * Copyright Ericsson AB 1997-2009. All Rights Reserved.
+ * 
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ * 
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ * 
+ * %CopyrightEnd%
+ */
+
+/* 
+ * This memmove assumes that both src and dst are aligned on an address
+ * divisible by 4 and that n is a multiple of four.
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#ifndef HAVE_MEMMOVE
+
+#define MEMCPY_LIMIT 12
+typedef unsigned long  u_long;
+typedef unsigned short u_short;
+
+static void copy_high(dst, src, n)
+char* dst; char* src; int n;
+{
+    dst += n;
+    src += n;
+
+    if (n >= MEMCPY_LIMIT) {
+	while(((u_long) dst) & 3) {
+	    *--dst = *--src;
+	    n--;
+	}
+	if ((((u_long) src) & 3) == 0) {
+	    while(n >= sizeof(u_long)) {
+		src -= sizeof(u_long);
+		dst -= sizeof(u_long);
+		*((u_long*)dst) = *((u_long*)src);
+		n -= sizeof(u_long);
+	    }
+	}
+	else if ((((u_short) src) & 3) == 2) {
+	    while(n >= sizeof(u_short)) {
+		src -= sizeof(u_short);
+		dst -= sizeof(u_short);
+		*((u_short*)dst) = *((u_short*)src);
+		n -= sizeof(u_short);
+	    }
+	}
+    }
+    while(n > 0) {
+	*--dst = *--src;
+	n--;
+    }
+}
+
+static void copy_low(dst, src, n)
+char* dst; char* src; int n;
+{
+    if (n >= MEMCPY_LIMIT) {
+	while(((u_long) dst) & 3) {
+	    *dst++ = *src++;
+	    n--;
+	}
+	if ((((u_long) src) & 3) == 0) {
+	    while(n >= sizeof(u_long)) {
+		*((u_long*)dst) = *((u_long*)src);
+		src += sizeof(u_long);
+		dst += sizeof(u_long);
+		n -= sizeof(u_long);
+	    }
+	}
+	else if ((((u_long) src) & 3) == 2) {
+	    while(n >= sizeof(u_short)) {
+		*((u_short*)dst) = *((u_short*)src);
+		src += sizeof(u_short);
+		dst += sizeof(u_short);
+		n -= sizeof(u_short);
+	    }
+	}
+    }
+    while(n > 0) {
+	*dst++ = *src++;
+	n--;
+    }
+}
+
+/*
+** Move memory (with overlap)
+*/
+void* memmove(dst, src, n)
+char* dst; char* src; int n;
+{
+    if (dst < src)
+	copy_low(dst, src, n);
+    else if (dst > src)
+	copy_high(dst, src, n);
+    return dst;
+}
+
+#endif /* HAVE_MEMMOVE */