1 files changed, 29 insertions, 0 deletions
diff --git a/src/string/memcpy.c b/src/string/memcpy.c
new file mode 100644
index 00000000..02cb4694
--- /dev/null
+++ b/src/string/memcpy.c
@@ -0,0 +1,29 @@
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#define SS (sizeof(size_t))
+#define ALIGN (sizeof(size_t)-1)
+#define ONES ((size_t)-1/UCHAR_MAX)
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	unsigned char *d = dest;
+	const unsigned char *s = src;
+
+	if (((uintptr_t)d & ALIGN) != ((uintptr_t)s & ALIGN))
+		goto misaligned;
+
+	for (; ((uintptr_t)d & ALIGN) && n; n--) *d++ = *s++;
+	if (n) {
+		size_t *wd = (void *)d;
+		const size_t *ws = (const void *)s;
+
+		for (; n>=SS; n-=SS) *wd++ = *ws++;
+		d = (void *)wd;
+		s = (const void *)ws;
+misaligned:
+		for (; n; n--) *d++ = *s++;
+	}
+	return dest;
+}