#define VIA $ec10
#define IRQTIME 50000
.(
.word devend
jmp prg1
.asc "keys",0
.data
status .byt 0
outstr .byt 0
.text
prg1
cmp #DC_RES
beq devini
pha
lda status
and #2
beq prgok
pla
lda #E_NOTIMP
sec
rts
prgok pla
cmp #DC_IRQ
beq devirq
jmp others
devini lda #0
sta status
/* sta instr*/
sta outstr
/************************ Reset ************************************/
jsr inikeys
lda VIA+VIA_ACR
and #%11011111
sta VIA+VIA_ACR
lda #%00100000
sta VIA+VIA_IFR
lda #%10100000
sta VIA+VIA_IER
lda #<IRQTIME
sta VIA+VIA_T2CL
lda #>IRQTIME
sta VIA+VIA_T2CH
/******* go on here or on error goto devx **************************/
rts1hi
/***************** here if stream over highwatermark ***************/
/*******************************************************************/
clc
rts
devx lda status
ora #2
sta status
lda #E_NOTIMP
sec
rts
devirq .(
/*************** Is interrupt for device? no, then irqend **********/
lda VIA+VIA_IFR
and #%00100000
beq irqend
lda #>IRQTIME
sta VIA+VIA_T2CH
/************************ here if irq for device *******************/
lda status
bpl tx
/**** get byte to ac - if non rx'd, goto nobyt **********************/
jsr getkey
bcs nobyt
txa
/*********************************************************************/
ldx outstr
jsr PUTC
bcs test
nobyt ldx outstr
lda #SC_STAT
jsr STRCMD
test bcc tx
cmp #E_NUL
bne tstwater
jsr rxoff
jmp tx
tstwater /*
cmp #E_SEMPTY
beq wl
tax
lda status
and #1
bne wh
txa
cmp #E_SFULL
beq wh
cmp #E_SHWM
bne twl
wh jsr rts1hi
bcc tx ; always
twl cmp #E_SLWM
bne tx
wl
/******** here action if stream below lowwatermark *******************/
/*********************************************************************/
*/
tx/*
lda status
rol
bpl irqhs
/******* hardware ready to send? if not goto irqhs *******************/
jmp irqhs
/*********************************************************************/
ldx instr
jsr GETC
bcs test2
/***************** send byte in ac **********************************/
/********************************************************************/
jmp irqhs
test2 cmp #E_EOF
bne irqhs
jsr txoff
*/
irqhs
/**************** clear interrupt at end of irq service ************/
/*******************************************************************/
irqend rts
.)
devonx jmp devon
others /*
cmp #DC_GS
bne o1
lda status
and #DC_SW_TX
bne devonx
tya
sta instr
jmp ok */
o1 cmp #DC_PS
bne o2
lda status
and #DC_SW_RX
bne devonx
sty outstr
okx jmp ok
o2 cmp #DC_RX_ON
bne o3
/********************* test if receive allowed ********************/
/************************ if not, goto onotimp ********************/
lda #DC_SW_RX
bne o2a
o3 cmp #DC_TX_ON
bne o4
/********************* test if send allowed ***********************/
jmp onotimp
/************************ if not, goto onotimp ********************/
lda #DC_SW_TX
o2a ora status
sta status
bne okx
o4 cmp #DC_RX_OFF
bne o5
rxoff lda status
and #DC_SW_RX
beq devoffx
ldx outstr
lda #SC_EOF
jsr STRCMD
lda status
and #255-DC_SW_RX
sta status
jsr rts1hi
bcc okx
devoffx jmp devoff
o5 /*
cmp #DC_TX_OFF
bne o6
txoff lda status
and #DC_SW_TX
beq devoffx
ldx instr
lda #SC_NUL
jsr STRCMD
lda status
and #255-DC_SW_TX
sta status
jmp ok
o6
cmp #DC_HS
bne o6a
/******************** here handshake ************************/
lda status
and #255-1
sta status
tya
and #1
ora status
sta status
/***********************************************************/
jmp ok
o6a cmp #DC_SPD
bne o7
/****************** here speed *****************************/
/***********************************************************/
jmp ok
*/
o7 cmp #DC_ST
bne o8
lda status,x
and #2
bne onotimp
/****************** here status report *********************/
/***********************************************************/
jmp ok
o8 cmp #DC_EXIT
bne onotimp
jsr rxoff
/* jsr txoff*/
lda status
ora #2
sta status
/****************** disable irq (Exit) *********************/
lda #%00100000
sta VIA+VIA_IER
/*********************************************************************/
ok lda #E_OK
.byt $2c
devon lda #E_DON
.byt $2c
devoff lda #E_DOFF
.byt $2c
onotimp lda #E_NOTIMP
cmp #1
rts
/************** other device code **********************************/
.data
lastkey .byt 0
.text
inikeys .(
lda #<-1
sta lastkey
lda #%00001111
sta VIA+VIA_DDRA
cmp VIA+VIA_DDRA
bne novia
lda #0
sta VIA+VIA_DRA
clc
rts
novia sec
rts
.)
getkey .(
ldx #0
g0 txa
lsr
lsr
sta VIA+VIA_DRA
g1 lda VIA+VIA_DRA
cmp VIA+VIA_DRA
bne g1
ldy #4
g2 rol
bcc pressed
inx
dey
bne g2
cpx #64
bcc g0
stx lastkey
nokey sec
rts
pressed cpx lastkey
stx lastkey
beq nokey
clc
rts
.)
/*********************************************************************/
devend .)
