;-----------------------------------------------------;
; Equates for a 48K+ Apple 2 (original, +, e, c, gs)
;ESC      = 27       ; "Cancel current input line" key
;BS       = 8        ; "Delete last keypress" key
;OP_OR    = '!'      ; Bit-wise OR operator
;linbuf   = $0200    ; input line buffer
;prgm     = $0800    ; VTL02B program grows from here
;himem    = $8000    ;   ... up to the top of user RAM
;vtl02c   = $8000    ; interpreter cold entry point
;                     (warm entry point is startok)
;KBD      = $c000    ; 128 + keypress if waiting
;KEYIN    = $fd0c    ; apple monitor keyin routine
;COUT     = $fded    ; apple monitor charout routine
;-----------------------------------------------------;
; Equates for the Kowalski 6502 simulator
ESC      = 27       ; "Cancel current input line" key
BS       = 8        ; "Delete last keypress" key
OP_OR    = '|'      ; Bit-wise OR operator
linbuf   = $0200    ; input line buffer
prgm     = $0400    ; VTL02B program grows from here
himem    = $F000    ;   ... up to the top of user RAM
vtl02c   = $FC00    ; interpreter cold entry point
;                     (warm entry point is startok)
io_area  = $f000      ;configure simulator terminal I/O
acia_tx  = io_area+1  ;acia tx data register
acia_rx  = io_area+4  ;acia rx data register
;=====================================================;

;============ Original I/O subroutines ===============;
;-----------------------------------------------------;
; Check for user keypress and return with (cc) if none
;   is pending.  Otherwise, fall through to inch
;   and return with (cs).
; 6 bytes
;inkey:
;    lda  KBD        ; is there a keypress waiting?
;    asl
;    bcc  outrts     ;   no: return with (cc)
; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Read key from stdin into a, echo, (cs)
; drop stack and abort to "OK" prompt if ctrl-C
; 16 bytes
;inch:
;    sty  dolr       ; save y reg
;    jsr  KEYIN      ; get a char from keyboard
;    ldy  dolr       ; restore y reg
;    and  #$7f       ; strip apple's hi-bit
;    cmp  #$03       ; ctrl-C?
;    bne  outch      ;   no: echo to terminal
;    jmp  start      ;   yes: abort to "OK" prompt
; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Print ASCII char in a to stdout, (cs)
; 9 bytes
;outch:
;    pha             ; save original char
;    ora  #$80       ; apples prefer "high" ASCII
;    jsr  COUT       ; emit char via apple monitor
;    pla             ; restore original char
;    sec             ; (by contract with callers)
;outrts:
;    rts
;-----------------------------------------------------;
;========== 2m5 SBC emulator I/O subroutines ============;
;-----------------------------------------------------;
; Check for user keypress and return if none
;   is pending.  Otherwise, check for ctrl-C and
;   return after next keypress.
;
inkey:
    lda  acia_rx    ; Is there a character waiting?
    beq  inkeyr     ;   no: return
    cmp  #3         ; is ctrl-c
    beq  istart     ;   yes: abort to OK prompt
inkeyp:
    lda  acia_rx    ; pause until next key
    beq  inkeyp
    cmp  #3         ; is ctrl-c
    beq  istart     ;   yes: abort to OK prompt
inkeyr:
    rts
; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Read key from stdin into a, echo, (cs)
; Dump stack and abort to "OK" prompt if ctrl-C
; 16 bytes
inch:
    lda  acia_rx    ; get character from rx register
    beq  inch       ; wait for character !=0
    cmp  #10        ; remove line feed to allow paste
    beq  inch       ; in the Kowalski I/O window
inch2:
    cmp  #$03       ; ctrl-C?
    bne  outch      ;   no: echo to terminal
istart:
    jmp  start      ;   yes: abort to "OK" prompt
; - - - - - - - - - - - - - - - - - - - - - - - - - - ;
; Print ascii char in a to stdout, (cs)
; 16 bytes
outch:
    cmp  #13        ; add line feed to carriage return
    bne  skip_cr
    lda  #10
    sta  acia_tx
    lda  #13
skip_cr:
    sta  acia_tx    ; emit char via transmit register
    sec             ; (by contract with callers)
    rts
;-----------------------------------------------------;

; In the Kowalski 6502 simulator some of the options
; below must be set manually.
;
;    .lf  vtl02ca2.lst  (set listfile in menu:
;                        Simulator->Options->Assembler)
;    .cr  6502
    .opt  Proc6502
;
; to run with I/O set terminal active:
;    Menu                     or   Key
;    Simulator->Options->Simulator [Ctrl-E]
;    Simulator->Assemble           [F7]
;    Simulator->Debugger           [F6]
;    Simulator->Run                [F5]
;    View->Input/output            [Alt-5]
;
;    .tf  vtl02ca2.obj,ap1  (optional save output to
;                             file: File->Save Code)