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xdef pgstart
absentry pgstart
*
*******************************************************************************
* Macros
*
PORTB equ $0001
DDRB equ $0003
SCHBDH equ $00C8
SCHBDL equ $00C9
SCICR2 equ $00CB
SCISR1 equ $00CC
SCIDRL equ $00CF
CRGFLG equ $0037
CRGINT equ $0038
RTICTL equ $003B
*
*******************************************************************************
* RTI Vector Section: [ $FFF0 to $FFF1 ]
*
org $FFF0
dc.w RTIISR
*
*******************************************************************************
* Data Section: [ $3000 to $30FF ]
*
org $3000
counter dc.w $0000
msg dc.b 'This program will print a $ every second',$00
numBuf ds.b $0002
dc.b $00
inNumBuf dc.w $0000
*
*******************************************************************************
* Program Section: [ $3100 to $3FFF ]
*
org $3100
pgstart
lds #pgstart
ldaa #1
staa SCHBDH
ldaa #$0C
staa SCICR2
ldaa #%00011001
staa RTICTL
bset CRGINT,#%10000000
bset CRGFLG,#%10000000
ldx #msg
jsr printmsg
cli
loop jsr getchar
tsta
beq loop
jsr putchar
bra loop
;******************************************************************************
; Subroutine Section
;
RTIISR bset CRGFLG,#%10000000
ldx counter
inx
stx counter
cpx #400
bne RTIDONE
ldx #0
stx counter
ldaa #'$'
jsr putchar
RTIDONE rti
getchar
brclr SCISR1,#%00100000,empty
ldaa SCIDRL
rts
empty clra
rts
PrintTwoDigitDecimal
pshx
pshd
pshy
ldy #numBuf
ConvertLoop ldx #10
idiv
cpd #0
beq CheckX
XNotZero addb #'0'
stab 1,y+
exg d,x
bra ConvertLoop
CheckX cpx #0
bne XNotZero
ldx #numBuf
jsr printmsg
puly
puld
pulx
rts
ReadTwoDigitDecimal
pshx
pshd
pshy
ldd #0
ReadLoop ldab 1,x+
beq ReadDone
cmpb #'0'
blt ReadDone
cmpb #'9'
bhi ReadDone
pshb
ldd inNumBuf
ldy #10
emul
std inNumBuf
pulb
subb #'0'
ldy inNumBuf
aby
sty inNumBuf
bra ReadLoop
ReadDone puly
puld
pulx
rts
putchar
brclr SCISR1,#%10000000,putchar
staa SCIDRL
rts
printmsg
pshx
psha
printLoop ldaa 1,x+
beq printDone
jsr putchar
bra printLoop
printDone pula
pulx
rts
;
;******************************************************************************
end
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