From 484afffcbd88f7e57e43b57541466a6998e516e3 Mon Sep 17 00:00:00 2001
From: Masayuki Tanaka <masayuki0812@mac.com>
Date: Tue, 23 Dec 2025 19:22:23 +0900
Subject: [PATCH] Fix SD read in CRC calculation

---
 Cart_Reader/Cart_Reader.ino | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Cart_Reader/Cart_Reader.ino b/Cart_Reader/Cart_Reader.ino
index 93993df8..619126ed 100644
--- a/Cart_Reader/Cart_Reader.ino
+++ b/Cart_Reader/Cart_Reader.ino
@@ -419,10 +419,10 @@ uint32_t calculateCRC(const byte* buffer, size_t length) {
 }
 
 uint32_t calculateCRC(FsFile& infile) {
-  uint32_t byte_count;
+  int32_t byte_count;
   uint32_t crc = 0xFFFFFFFF;
 
-  while ((byte_count = infile.read(sdBuffer, sizeof(sdBuffer))) != 0) {
+  while ((byte_count = infile.read(sdBuffer, sizeof(sdBuffer))) > 0) {
     crc = updateCRC(sdBuffer, byte_count, crc);
   }
   return ~crc;