C02/include/py65.a02

;py65mon program initialization code for c02 programs

;System Specific ASCII Key Mappings
DELKEY  EQU $08     ;Delete/Backspace Key (Backspace)
ESCKEY  EQU $1B     ;Escape/Stop Key      (Escape)
RTNKEY  EQU $0D     ;Return/Enter Key     (Carriage Return)

;Zero Page Locations
SRCLO   EQU $30     ;Source String Pointer (stdio.a02)
SRCHI   EQU $31
DSTLO   EQU $32     ;Destination String Pointer (string.a02)
DSTHI   EQU $33
BLKLO   EQU $34     ;Block Segment Pointer (block.a02)
BLKHI   EQU $35
STKLO   EQU $36     ;Stack Pointer (stack.a02)
STKHI   EQU $37

RDSEED  EQU $3E     ;Pseudo-RANDOM Seed
RANDOM  EQU $3F     ;Pseudo-RANDOM Number Storage

TEMP0   EQU $40     ;Temporary Storage
TEMP1   EQU $41
TEMP2   EQU $42
TEMP3   EQU $43

BLKSLO  EQU $46     ;Block Start Address
BLKSHI  EQU $47
BLKELO  EQU $48     ;Block End Address
BLKEHI  EQU $49
BLKLEN  EQU $4A     ;Block Segment Length     

STKSLO  EQU $4C     ;Stack Start Address
STKSHI  EQU $4D
STKELO  EQU $4E     ;Stack End Address
STKEHI  EQU $4F

;Memory Mapped I/O 
PUTCON  EQU $F001   ;Write Character to Console
GETCON  EQU $F004   ;Read Character from Console

        ORG $0200   ;START Directly Above Stack

START:  JMP MAIN    ;Execute Program

;Poll Character from Keyboard
POLKEY: INC RDSEED  ;Cycle the RANDOM Seed (if not provided by system)
        LDA GETCON  ;Read Character from Console
        RTS

;Read Character from Console
GETKEY  JSR POLKEY  ;Get Raw Key Character
        CMP #$E0
        BEQ GETKEX  ;If Not E0 Extended Key 
        ORA #$00    ;  Set Status Flags
        RTS         ;  and Return
GETKEX: JSR POLKEY  ;Else Get Second Byte
        ORA #$80    ;  Set High Bit
        RTS         ;  and Return

;Wait for Character from Console
GETCHR: JSR GETKEY  ;Read Character from Console
        BEQ GETCHR  ;  Loop if None Received
        RTS

;Delete Previous Character
DELCHR: LDA #$08    ;Load Backspace into Accumulator
        JSR PUTCHR  ;  and Print it
        LDA #$20    ;Load Space into Accumulater
        JSR PUTCHR  ;  and Print it
        LDA #$08    ;Load Backspace into Accumulator
        JMP PUTCHR  ;  and Print it

;Advance Character to Next line
NEWLIN: LDA #$0D    ;Load C/R into Accumulator
        JSR PUTCHR  ;  and Print it
        LDA #$0A    ;Load L/F into Accumulater
                    ;  and fall into PRCHR

;Print Character to Console
PUTCHR STA PUTCON  ;Write Character to Console
        RTS

EXIT:   BRK        ;Return to Monitor

        INCLUDE "../include/prbyte.a02" ;PRBYTE and PRHEX routines