spo-lab4b.s

; ROM routines
define		SCINIT		    $ff81 ; initialize/clear screen
define		CHRIN		    $ffcf ; input character from keyboard
define		CHROUT		    $ffd2 ; output character to screen
define		SCREEN		    $ffed ; get screen size
define		PLOT		    $fff0 ; get/set cursor coordinates
define		X               $f5
define		Y               $f6
define		SCREEN_PTR      $f7
define		SCREEN_PTR_HI   $f8
define          save1           $10

        jsr SCINIT
        ldx #$00
        ldy #$00
        jmp print_form
            
cursor: 
        ; delay the cursor so it can blink on high speed too
        sec                  ; set PLOT to get mode (carry = 1)
        jsr PLOT             ; get the cursor position
        
        eor #$80             ; reverse video
        ldy #$00             ; clear y
        sta (SCREEN_PTR),y   ; save the changed char
        rts                  ; return
            
handle_key:  
        cmp #$0d
        beq handle_enter
        jmp print
        
handle_enter:
        ldy Y
        cpy #$04             ; enter at the last line means all input is done
        beq print_label
        jmp print
        
print:
        sec
        jsr CHROUT           ; print the char
        jmp main
        
print_label:
        ldx #$00
        ldy #$06
        clc                  ; set PLOT to set mode (carry = 0)
        jsr PLOT             ; set the cursor position
        
        ldx #$00
        ldy #$00
        jmp print_label_loop

main:
        sec                  ; set PLOT to get mode (carry = 1)
        jsr PLOT             ; get the cursor position
        
        cpx #$0d             ; limit 14 chars from left
        bmi cursor_limit_x_min
        
        cpx #$37             ; limit 40 chars of input
        bpl cursor_limit_x_max
        
        cpy #$05             ; limit the cursor to the form area
        bpl cursor_limit_y_max
        
        jsr cursor           ; blink cursor - reverse video
        jsr cursor           ; blink curosr - reverse it back
        
        jsr CHRIN            ; load the typed key into A
        bne handle_key       ; if some key was pressed
        
        jmp main
        
print_label_loop:
        lda label,y
        beq cursor_reset
        
        jsr CHROUT
        iny
        bne print_label_loop
        
print_form:   
        lda form,y
        beq cursor_reset
        
        jsr CHROUT
        iny
        bne print_form

set_cursor:
        clc                  ; set PLOT to set mode (carry = 0)
        jsr PLOT             ; set the cursor position
        jmp main

cursor_limit_x_min:
        ldx #$0d
        jmp set_cursor
        
cursor_limit_x_max:
        ldx #$36
        jmp set_cursor
        
cursor_limit_y_max:
        ldy #$04
        jmp set_cursor
        
cursor_reset:
        ldx #$0d
        ldy #$00
        jmp set_cursor
        
form:
    dcb "U","s","e","r", 32,"N","a","m","e", 32, 32,":",32,13
    dcb "A","d","d","r","e","s","s", 32, 32, 32, 32,":",32,13
    dcb "C","i","t","y", 32, 32, 32, 32, 32, 32, 32,":",32,13
    dcb "P","r","o","v","i","n","c","e", 32, 32, 32,":",32,13
    dcb "P","o","s","t","a","l", 32,"C","o","d","e",":",32,00
    
label:
    dcb "Y","o","u","r", 32
    dcb "o","r","d","e","r", 32
    dcb "w","i","l","l", 32,
    dcb "b","e", 32 
    dcb "d","e","l","i","v","e","r","e","d", 32
    dcb "t","o",":",13,13,00