; ============================================================
;       SAMPLE WEDGE - ADDING FOUR NEW BASIC COMMANDS
; ============================================================
;                        VERSION 2
;            (c)2002, (c)2004 BY SCOTT JULIAN
;                    ALPHAWORKS PTY LTD

; THIS SAMPLE SHOW YOU HOW TO ADD FOUR NEW BASIC COMMANDS. THE
; COMMANDS ARE SIMPLE AND USE SHOULD BE ABLE TO CREATE MORE
; COMMANDS OF YOUR OWN USING THIS FRAMEWORK.

; 	!CLS 			CLEAR SCREEN
;	!BRD 			CHANGE BORDER COLOUR
; 	!SCR 			CHANGE SCREEN COLOUR
; 	!TXT 			CHANGE TEXT COLOUR
;	!HELP			DISPLAY LIST OF COMMANDS

; ============================================================
;  STARTUP
; ============================================================

* = $C000	; START ADDRESS 49152


; ============================================================
;  KERNAL
; ============================================================

CHRGET    = $0073
TXTPTR    = $7A
IERROR    = $0300
IMAIN     = $0302
IGONE     = $0308
GONE      = $A7E4
CHKCOM    = $AEFD
FRMNUM    = $AD8A
GETADR    = $B7F7
CHROUT    = $FFD2
BORDER    = $D020
SCREEN    = $D021
TEXT	  = $0286

; ============================================================
;  SETUP SCREEN DISPLAY
; ============================================================

	    LDA #4		; CHANGE BORDER COLOUR TO 
	    STA BORDER		; BLACK
	    LDA #147		; PRINT CHR$(147) TO CLEAR
	    JSR CHROUT		; SCREEN

            LDY #$00
DISPLAY     LDA TITLE,Y
       	    JSR CHROUT
            INY
            CPY #23		; NUMBER OF CHARARTERS TO READ
            BNE DISPLAY


; ============================================================
;  CHANGE BASIC COMMAND POINTERS
; ============================================================

INIT        LDX #<NEWBASIC
            LDY #>NEWBASIC
            STX IGONE
            STY IGONE+1
            RTS

            LDX #$83
            LDY #$A4
            STX IMAIN		; ($0302)
            STY IMAIN+1   	; ($0303)


; ============================================================
;  CHECK FOR NEW COMMANDS, IS FIRST CHARACTER !
; ============================================================

NEWBASIC    JSR CHRGET    	; GET CHARACTER
            CMP #'!'      	; IS IT A "!" ?
            BEQ CHK       	; YES, CONTINUE
            JMP GONE+3    	; NORMAL WORD


; ============================================================
;  CHECK WHICH NEW COMMAND HAS BEEN ISSUED
; ============================================================

CHK         JSR CHRGET    	; GET NEXT CHARACTER
            CMP #'C'      	; IS IT A "C" ?
            BEQ CLS       	; YES, JUMP TO CLS
            CMP #'B'      	; IS IT A "B" ?
            BEQ BDR       	; YES, JUMP TO BRD
            CMP #'S'      	; IS IT A "S" ?
            BEQ SCR		; YES, JUMP SCR
            CMP #'T' 		; IS IT A "T" ?
            BEQ TEX		; YES, JUMP TEX
	    CMP #'H'		; IS IT A "H" ?
	    BEQ HELP	        ; YES, JUMP HELP
            JMP (IERROR)	; JUMP TO ERROR CHECK 


; ============================================================
;  NEW COMMAND TO CLEAR SCREEN
; ============================================================

CLS         JSR CHRGET    	; GET THE L
            JSR CHRGET    	; GET THE S
            LDA #$93      	; LOAD A WITH CHR$(147)
            JSR CHROUT    	; PRINT A
            JMP GONE


; ============================================================
;  NEW COMMAND TO CHANGE SCREEN COLOUR 
; ============================================================

SCR	JSR CHRGET  		; GET THE C
	JSR CHRGET  		; GET THE R
        JSR CHRGET  		; GET THE ,
        JSR CHKCOM  		; SKIP THE COMMA
        JSR FRMNUM 	 	; EVALUATE NUMBER
        JSR GETADR  		; CONVERT TO A 2-BYTE INTEGER
                        	; A HAS HI BYTE
                        	; Y HAS LO BYTE
        STY SCREEN   		; PUT IN SCREEN COLOUR
        JMP END2


; ============================================================
;  NEW COMMAND TO CHANGE TEXT COLOUR 
; ============================================================

TEX     JSR CHRGET             ; GET THE X
        JSR CHRGET             ; GET THE T
        JSR CHRGET             ; GET THE ,
        JSR CHKCOM             ; SKIP THE COMMA
        JSR FRMNUM             ; EVALUATE NUMBER
        JSR GETADR             ; CONVERT TO A 2-BYTE INTEGER
                               ; A HAS HI BYTE
                               ; Y HAS LO BYTE
        STY TEXT               ; PUT IN BORDER COLOUR
        JMP END2


; ============================================================
;  NEW COMMAND TO CHANGE BORDER COLOUR 
; ============================================================

BDR     JSR CHRGET             ; GET THE D
        JSR CHRGET             ; GET THE R
        JSR CHRGET             ; GET THE ,
        JSR CHKCOM             ; SKIP THE COMMA
        JSR FRMNUM             ; EVALUATE NUMBER
        JSR GETADR             ; CONVERT TO A 2-BYTE INTEGER
                               ; A HAS HI BYTE
                               ; Y HAS LO BYTE
        STY BORDER             ; PUT IN BORDER COLOUR
        JMP END2


; ============================================================
;  HELP, DISPLAY ALL COMMANDS AND SYNTX 
; ============================================================

HELP	JSR CHRGET             ; GET THE E
	JSR CHRGET             ; GET THE L
	JSR CHRGET             ; GET THE P

            LDY #$00
DISHELP     LDA HELPTX,Y
       	    JSR CHROUT
            INY
            CPY #170		; NUMBER OF CHARARTERS TO READ
            BNE DISHELP
            JMP GONE


; ============================================================
;  RETURN TO BASIC PROMPT (READY) 
; ============================================================

END2    SEC
        LDA TXTPTR
        SBC #$01
        STA TXTPTR
        LDA TXTPTR+1
        SBC #$00
        STA TXTPTR+1
        JMP GONE

; ============================================================
;  TEXT DISPLAY 
; ============================================================

TITLE   .BYTE $0D
	.TEXT "ALPHAWORKS BASIC V2.0"	; 20 CHARACTERS LONG
	.BYTE $0D

HELPTX	.BYTE $0D
	.TEXT "!TXT,(0-15)  CHANGES COLOUR OF TEXT"
	.BYTE $0D
	.TEXT "!BRD,(0-15)  CHANGES COLOUR OF BORDER"
	.BYTE $0D
	.TEXT "!SCR,(0-15)  CHANGES COLOUR OF SCREEN"
	.BYTE $0D
	.TEXT "!CLS         CLEARS SCREEN"
	.BYTE $0D
	.TEXT "!HELP        DISPLAYS COMMANDS"