fixed crc16 implementation for large data

src/shellmatta_crc.c

@@ -198,7 +198,7 @@ uint16_t crc16Fast(const char* data, uint32_t size, const uint16_t* lookupTable)
 uint16_t crc16Slow(const char* data, uint32_t size)
 {
     uint16_t crc = 0;
-    uint8_t i, j;
+    uint32_t i, j;
 
     for (i = 0; i < size; i++) {
         crc = crc ^ (data[i] << BITS_PER_BYTE);