Quectel Delta Radio Firmware Upgrade support - libmts-io implementation

Fixed Quectel checksum calculation algorithm to correctly handle odd file sizes.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/MTS_IO_QuectelRadio.cpp b/src/MTS_IO_QuectelRadio.cpp
index 22fa92f..39c0601 100644
--- a/src/MTS_IO_QuectelRadio.cpp
+++ b/src/MTS_IO_QuectelRadio.cpp
@@ -981,8 +981,10 @@ uint16_t QuectelRadio::getQuectelChecksum(const void* data, size_t nBytes) {
     for (size_t i = 0; i < nBytes; i += 2) {
         // If the number of the characters is odd, set the last character as the high 8 bit, and the low 8 bit as 0,
         // and then use an XOR operator to calculate the checksum.
+        bool bHasLowByte = (i + 1 < nBytes);
+
         uint8_t high = castData[i];
-        uint8_t low = (i < nBytes) ? (castData[i+1]) : (0);
+        uint8_t low = bHasLowByte ? (castData[i+1]) : (0);
 
         uint16_t iFragment = bytesToUint16(high, low);
         updateQuectelChecksum(iChecksum, iFragment);