I have developed a function to calculate a checksum byte for a Roland SysEx message. I got it working with some helper functions, especially for the needed HexChar to decimal conversion.
But the programmer’s life would be much easier if a function “SM_GetValue(sm, index) Returns integer” was available in GP Script.
→ Similar to the existing "SM_ChangeValue(sm, index, newValue)
In this case you could quickly retrieve single bytes as integer from the SysEx message without processing the SysEx message in parallel as hex string and having to perform “expensive” string operations and hex-decimal conversions.