; Program initialization code for C02 programs
; Template for System Specific Code

        ORG $0400   ;Program Start Address

;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)
NULKEY  EQU $00     ;No Key was Pressed   (Null)

;Zero Page Locations
SRCPTR  EQU $10
DSTPTR  EQU $12
BFRLO   EQU $14     ;Work Buffer Pointer
BFRHI   EQU $15

STKSAV  EQU $1D     ;Stack Pointer Storage
RDSEED  EQU $1E     ;Pseudo-RANDOM Seed
RANDOM  EQU $1F     ;Pseudo-RANDOM Number Storage

TEMP0   EQU $20     ;Temporary Storage
TEMP1   EQU $21
TEMP2   EQU $22
TEMP3   EQU $22

BLKBGN  EQU $30     ;Block Start Address
BLKEND  EQU $32     ;Block End Address
BLKPTR  EQU $34     ;Block Pointer
BLKLEN  EQU $36     ;Block Segment Length     

STKSLO  EQU $48     ;Stack Start Address
STKSHI  EQU $49
STKELO  EQU $4A     ;Stack End Address
STKEHI  EQU $4B
STKLO   EQU $4C     ;Stack Pointer
STKHI   EQU $4D

;Memory Mapped I/O
IOBASE  EQU $E000
IOINIT  EQU IOBASE+0 ;Clear Terminal Window
IOPUTC  EQU IOBASE+1 ;Put Character
IOPUTR  EQU IOBASE+2 ;Put Raw Character
IOPUTH  EQU IOBASE+3 ;Put as Hexadecimal Number
IOGETC  EQU IOBASE+4 ;Get Character
IOPOSX  EQU IOBASE+5 ;Set Cursor X Position 
IOPOSY  EQU IOBASE+6 ;Set Cursor Y Position

START:  LDX #$FF    ;Initialize Stack Pointer
        TXS         ;
        STX IOINIT  ;Clear Screen
        JMP MAIN    ;Execute Program

;Exit Program and Return to Monitor
EXIT:   BRK         ;Halt Debugger

;Read Character from Console
GETKEY  EQU $FFE0   ;Emulator CHRIN Routine

;Poll Character from Keyboard
POLKEY: INC RDSEED  ;Cycle the Random Seed 
        LDA IOGETC  ;Code Read from Keyboard         
        RTS

;Wait for Character from Console
GETCHR: JSR POLKEY  ;Usually calls PLKEY 
        BEQ GETCHR   ;  until a non-zero is returned
        RTS         

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

;Advance Character to Next line
NEWLIN: LDA #$0D    ;Load Carriage Return
        JSR PUTCHR  ;And Print It
        LDA #$0A    ;Load Line Feed

;Print Character to Console
PUTCHR: STA IOPUTC  ;Write Character to Screen
        RTS

;Print Hexadecimal Digit
PRHEX:  AND #$0F
        ORA #'0'
        BNE PUTCHR

;Print Hexadecimal Byte
PRBYTE: STA IOPUTH  ;Put as Hexadecimal Number
        RTS

        INCLUDE "putstr.a02" ;PUTSTR routine