My digital logic class was offering extra credit, which included programming a game in the classe’s cpu, i281, assembly language. I would say making this game was the funnest part of the class yet (still have finals left).
The game is similiar to wack the mole. A “mole” pops out of one of the displays, and you need to smack it with the corresponding switch. The longer you fail to smack it, the bigger the mole gets. Once it’s to big, you have failed to smack it in time, so game over. If it’s not game over, than another mole should pop up, and so on. The game is hard programmed to last for no more than 4 official rounds, and for the moles to pop up in the same order. The sequence of which displays to pop out of are defined by “sequence” in the DMEM.
I would want the sequence to be random. One way I am thinking of how this could work is by having a start button before the game starts. There could be a timer running that stops once the user starts the game. This could give us a somewhat psuedo seed if we have our timer running fast. I would also want the current round to show up on far left display. Another way may be using xorshift . The issue with xorshift is implementing it alongside the game all in 64 instructions.
.data
display BYTE 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 ; MS - LS
sequence BYTE 1 , 4 , 3 , 6
gameRun BYTE 0
shiftState BYTE ? , ? ; [shiftState + 1] is irrelevant
switch BYTE ?
.code
NOOP
NOOP
LOAD D , [ sequence ]; start popup display
Beg: INPUTD [ switch ]
LOAD B , [ switch ]
LOADI C , 0 ; not for checking here
LOADI A , 0 ; index for loop
LftShift: CMP A , D ; shifts B left D times
; LftShift to UpdateDisplay formats B to 1 bit status
; of corresponding switch to "mole" display
BRGE LftShiftEnd
SHIFTL B
ADDI A , 1
JUMP LftShift
LftShiftEnd: SHIFTR B ; carry flag updates shifted out bit
; would be nice if you could somehow get the carry flag bit instead of this
SHIFTR B
SHIFTR B
SHIFTR B
SHIFTR B
SHIFTR B
SHIFTR B
STOREF [ shiftState + C ] , B ; if running from checking then last byte of this array ; shiftState + 0 states original and others arent so we can get out of a branch here
JUMP Checking
UpdateDisplay: LOADF A , [ display + D ] ; get current display
SHIFTL A ; expand
ADDI A , 1 ; expand
STOREF [ display + D ] , A ; expand
SUBI A , 127 ; when display fully expanded
BRE Exit
LOADI C , 1 ; Checking starts here
LOADI A , 0 ; reset index for loop
INPUTD [ switch ]
LOAD B , [ switch ]
JUMP LftShift
Checking: LOAD A , [shiftState + 0] ; original before start of mole
CMP A , B ; no need to use shiftState + 1, thats to get out of a branch
BRE UpdateDisplay
LOAD A , [ gameRun ]
ADDI A , 1
LOADF D , [ sequence + A ]
STORE [ gameRun ] , A
JUMP Beg
Exit: NOOP
JUMP Exit
