Integrate LZ4 library, compress the ramdisk

kernel/libk/string.c

@@ -9,13 +9,13 @@ size_t memset (void* dst, uint8_t b, size_t n) {
   return i;
 }
 
-size_t memcpy (void* dst, const void* src, size_t n) {
+void* memcpy (void* dst, const void* src, size_t n) {
   uint8_t* dst1 = dst;
   const uint8_t* src1 = src;
   size_t i;
   for (i = 0; i < n; i++)
     dst1[i] = src1[i];
-  return i;
+  return dst;
 }
 
 // SOURCE: https://stackoverflow.com/a/48967408
@@ -92,3 +92,24 @@ char* strncat (char* dest, const char* src, size_t n) {
   *ptr = '\0';
   return dest;
 }
+
+void* memmove (void* dest, const void* src, unsigned int n) {
+  unsigned char isCopyRequire = 0; // flag bit
+  char* pcSource = (char*)src;
+  char* pcDstn = (char*)dest;
+  // return if pcDstn and pcSource is NULL
+  if ((pcSource == NULL) || (pcDstn == NULL)) {
+    return NULL;
+  }
+  // overlap buffer
+  if ((pcSource < pcDstn) && (pcDstn < pcSource + n)) {
+    for (pcDstn += n, pcSource += n; n--;) {
+      *--pcDstn = *--pcSource;
+    }
+  } else {
+    while (n--) {
+      *pcDstn++ = *pcSource++;
+    }
+  }
+  return dest;
+}