mirror of
https://github.com/nathanriggs/AppleIIAsm-Collection.git
synced 2026-10-24 16:02:19 +00:00
37 lines
1.2 KiB
NASM
37 lines
1.2 KiB
NASM
*
|
|
*``````````````````````````````*
|
|
* ADDIT16 (NATHAN RIGGS) *
|
|
* *
|
|
* ADD TWO 16-BIT VALUES. *
|
|
* *
|
|
* INPUT: *
|
|
* *
|
|
* WPAR1 = AUGEND *
|
|
* WPAR2 = ADDEND *
|
|
* *
|
|
* *
|
|
* DESTROY: NZCIDV *
|
|
* ^^^ ^ *
|
|
* *
|
|
* CYCLES: 40 *
|
|
* SIZE: 24 BYTES *
|
|
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
|
|
*
|
|
]ADD1 EQU ZPW1 ; FIRST ARGUMENT
|
|
]ADD2 EQU ZPW2 ; SECOND ARGUMENT
|
|
*
|
|
ADDIT16
|
|
LDA #2 ; {2C2B} PUT SUMMAND LENGTH
|
|
STA RETLEN ; {4C3B} IN RETLEN
|
|
LDA ]ADD1 ; {3C2B} ADD LOBYTES
|
|
CLC ; {2C1B} CLEAR CARRY
|
|
ADC ]ADD2 ; {3C2B}
|
|
TAY ; {2C1B} TEMPORARY STORE IN .Y
|
|
LDA ]ADD1+1 ; {3C2B} ADD HIBYTES
|
|
ADC ]ADD2+1 ; {3C2B}
|
|
TAX ; {2C1B} STORE IN .X
|
|
TYA ; {2C1B} XFER LOBYTE TO .A
|
|
STA RETURN ; {4C3B} ALSO PASS BACK IN RETURN
|
|
STX RETURN+1 ; {4C3B} TO KEEP CONSISTENT
|
|
RTS ; {6C1B}
|