On 23/11/15 13:45, htio2 wrote: > but avr is setting its short and int to 8 bit .... > The AVR is an 8-bit cpu, but "int" on the AVR is 16-bit (as is "short"). There is an option "-mint8" to make "int" and "short" 8-bit on the AVR, but it is not supported by the libraries and I believe has been deprecated in the compiler itself. Even if the cpu you are porting to is 8-bit, keep short and int at 16-bit. That is the minimum required for standard C, and no one will thank you for making a non-standard C port. Of course, you should make heavy use of uint8_t and int8_t in library codes and any other support code if it is an 8-bit target, but keep short and int standard.