Add memcpy

sys/kern/libc.c

@@ -49,3 +49,18 @@ memset(void *dst, uint8_t c, size_t length)
     return dst;
 }
 
+void *
+memcpy(void *dst, const void *src, size_t length)
+{
+    uint8_t *d = (uint8_t *)dst;
+    const uint8_t *s = (const uint8_t *)src;
+
+    do {
+	*d = *s;
+	d += 1;
+	s += 1;
+    } while (--length != 0);
+
+    return dst;
+}
+