Warning with RP2040 and other platforms

[HWHardsoft]

Hi,

your Modbus library works fine for me, but I see a warning after every compilation with a non AVR platform like RP2040. Can you fix this?

In file included from e:\Projekte\Arduino\Sketch\libraries\CSE_ModbusRTU\src\CSE_ModbusRTU.cpp:15:
e:\Projekte\Arduino\Sketch\libraries\CSE_ModbusRTU\src\CSE_ModbusRTU.cpp: In member function 'bool CSE_ModbusRTU_ADU::clear()':
e:\Projekte\Arduino\Sketch\libraries\CSE_ModbusRTU\src\CSE_ModbusRTU.h:35:57: warning: unsigned conversion from 'int' to 'uint8_t' {aka 'unsigned char'} changes value from '256' to '0' [-Woverflow]
   35 | #define   MODBUS_RTU_ADU_LENGTH_MAX                     256
      |                                                         ^~~
e:\Projekte\Arduino\Sketch\libraries\CSE_ModbusRTU\src\CSE_ModbusRTU.cpp:68:20: note: in expansion of macro 'MODBUS_RTU_ADU_LENGTH_MAX'
   68 |   return clear (0, MODBUS_RTU_ADU_LENGTH_MAX);
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~
Sketch uses 70512 bytes (0%) of program storage space. Maximum is 16773120 bytes.
Global variables use 10448 bytes (3%) of dynamic memory, leaving 251696 bytes for local variables. Maximum is 262144 bytes.
 

BR

Hartmut

[vishnumaiea]

The warning occurs because the defined constants are implicitly treated as signed integers by the compiler. When such values are passed to functions, it can create confusion. I have explicitly converted all of the constants to be unsigned integers. This should hopefully fix the warning. Please pull the latest changes and test.

[HWHardsoft]

Looks much better now! I've tested the latest code with Adafruit Feather M0 Express and Sparkfun Thingplus RP2040