123456789101112131415161718192021222324252627 |
- .define Adi2
- .sect .text
- .sect .rom
- .sect .data
- .sect .bss
- .sect .text
- ! This subroutine adds two twobyte integers.
- ! The first operand is on the top of the stack, the second operand
- ! is in the AX registerpair.
- ! The result is returned in registerpair AX.
- Adi2:
- sta ARTH+1 ! second operand (highbyte)
- stx ARTH ! second operand (lowbyte)
- jsr Pop ! get first operand
- pha ! save A
- clc
- txa
- adc ARTH ! add lowbytes
- tax
- pla ! get A
- adc ARTH+1 ! add the highbytes
- rts
|