Pushxx() pushes the assigned value onto the Stack.
Popxx() pops the top value from the Stack.
The function is the same as the machine command Push/Pop. After pushing bytes onto the stack you MUST pop the same number of bytes in the same level of code prior to exiting.
PushByte(avr.SREG) cli MyFunction(1,2,3) avr.SREG = PopByte()