From Lazarus-ccr

[edit] General information

The FPC-AVR port is currently experimental and non working. It uses the GCC AVR tool chain and will be compatible with GCC regarding calling conventions etc.

[edit] Implementation details

FPC considers AVR being a 16 bit CPU. So the type tregister actually describes a register pair being the second register implicitly named.

[edit] Resources

• General information: http://en.wikipedia.org/wiki/Atmel_AVR
• Atmel site: http://www.atmel.com/products/avr32/default.asp
• Calling conventions: http://www.nongnu.org/avr-libc/user-manual/FAQ.html#faq_reg_usage