TOFISRA equ $D1
TOFM equ $80
TMSK2 equ $1024
TFLG2 equ $1025
PORTB equ $1004
PORTC equ $1003
X1 equ %00000001
X2 equ %00000010
X3 equ %00000100
XS equ %00000111
Y1 equ %11110001
Y2 equ %11110010
Y3 equ %11110100
Y4 equ %11111000
YS equ %00001111
BUFSIZ equ 20
OUTA equ $ffb8 ;?????
table fcb $31, $32, $33, $34, $35, $36, $37, $38, $39, $2A, $30, $23
org $DFD0
inptr rmb 2
outptr rmb 2
buffer rmb BUFSIZ
keystate rmb 1
row rmb 1
column rmb 1
org $D000
init sei ;disable interrupts during setup
ldx #tofisr ;install our interrupt
stx TOFISRA ; service routine
clr keystate
ldaa #0
staa PORTB ; code to set 3 output pins driving X1-3 to zero here
;staa PORTC
ldaa TMSK2
oraa #TOFM ;enable TOF interrupt
staa TMSK2
ldx #buffer
stx inptr ;code to initialize circular buffer for key codes here
stx outptr
cli ;let them start
main ldx outptr
cpx inptr ;poll buffer looking for keys
beq main
ldaa 0,x
jsr OUTA ; code to extract key code from buffer and send to screen here
inx
cpx #buffer + BUFSIZ
bne fine
ldx #buffer
fine stx outptr
bra main
tofisr ;clr keypress ;0 indicates no keypress
ldaa keystate
cmpa #0
beq state0
cmpa #1
beq state1
cmpa #2
beq state2a
cmpa #3
beq state3a
bra state0 ;error catch
state2a jmp state2
state3a jmp state3
; place code to read port containing Y1-4 values here
; compare to %1111 on those bits
; if not all 1s inc keypress to show key being pressed
;place keystate breakout code here to go to state0 - state4
state0 ldaa PORTC
anda #%00001111
cmpa #YS ;no key pressed?
beq donei
;inc keypress
ldaa #1
staa keystate ;make and set next state decision
donei jmp tofrtn
state1 ldaa PORTC
anda #%00001111
cmpa #YS ;no key pressed?
beq donej
;inc keypress
ldaa #2
staa keystate ;make and set next state decision
ldaa PORTC
anda #%00001111
cmpa #~Y1
beq set1
cmpa #~Y2
beq set2
cmpa #~Y3
beq set3
ldaa #3
bra join4
set1 ldaa #0
bra join4
set2 ldaa #1
bra join4
set3 ldaa #2
join4 staa row
ldab #~X1
stab PORTB
ldaa PORTC
anda #%00001111
cmpa #YS
bne found1
ldab #~X2
stab PORTB
ldaa PORTC
anda #%00001111
cmpa #YS
bne found2
ldaa #2
bra joinf
found1 ldaa #0
bra joinf
found2 ldaa #1
joinf staa column
ldaa #0
staa PORTB
ldaa row
lsla
adda row
adda column
ldx #table
tab
abx
ldaa 0,x ;decode key ~~~~~~~~~~~~~~~~~
ldx inptr
staa 0,x
inx
cpx #buffer + BUFSIZ
bne fine2
ldx #buffer
fine2 stx inptr
bra donep
donej ldaa #0 ; if next state is 2 decode key and place in buffer
staa keystate
donep bra tofrtn
state2 ldaa PORTC
anda #%00001111 ;make and set next state decision
cmpa #YS ;key pressed?
bne donek
ldaa #3
staa keystate
donek bra tofrtn
state3 ldaa PORTC ;make and set next state decision
anda #%00001111
cmpa #YS ;key pressed?
bne donem
ldaa #0
staa keystate
bra donen
donem ldaa #2
staa keystate
donen bra tofrtn
tofrtn ldaa #TOFM
staa TFLG2 ;clear TOF event
rti |
