SixtyPical/eg/demo.60pical

assign byte table screen $0400
assign byte table screen2 1274
assign byte table screen3 1524
assign byte table screen4 1774

assign byte table colormap 55296
assign byte table colormap2 55546
assign byte table colormap3 55796
assign byte table colormap4 56046

assign byte vic_border 53280
assign byte table vic_bg 53281

assign vector cinv 788
reserve vector save_cinv

; TODO: this should be a word

assign byte pos_lo $fb
assign byte pos_hi $fc

reserve byte value

reserve byte m_hi
reserve byte m_lo
reserve byte n_hi
reserve byte n_lo

routine main {
    lda #5
    sta vic_border
    lda #0
    sta vic_bg
    jsr reset_pos
    jsr clear_screen
    sei {
        copy vector cinv to save_cinv
        copy routine our_cinv to cinv
    }
    clc
    repeat bcc { }
}

routine reset_pos {
    lda #$00
    sta pos_lo
    lda #$04
    sta pos_hi
}

routine our_cinv {
    lda value
    inc value
    ldy #0
    sta (pos_lo), y
    jsr increment_pos
    jsr compare_pos
    if beq {
        jsr reset_pos
    } else {
    }
    jmp save_cinv
}

routine increment_pos {
    clc
    lda pos_lo
    adc #1
    sta pos_lo
    lda pos_hi
    adc #0
    sta pos_hi
}

routine compare_pos {
    lda pos_lo
    sta m_lo
    lda pos_hi
    sta m_hi
    lda #$07
    sta n_hi
    lda #$e8
    sta n_lo
    jsr compare_16_bit
}

routine compare_16_bit {
    lda m_hi
    cmp n_hi
    if beq {
        lda m_lo
        cmp n_lo
    } else {
    }
}

routine clear_screen {
    ldy #0
    repeat bne {
        lda #1
        sta colormap, y
        sta colormap2, y
        sta colormap3, y
        sta colormap4, y
        
        lda #32
        sta screen, y
        sta screen2, y
        sta screen3, y
        sta screen4, y

        iny
        cpy #250
    }
}