;
; example.asm for TR8
;
.org 0

; address of the frame interrupt vector
.equ INT_VECT 0xff00

    ; setup an int handler so we
    ; can use the frame int to sync
    ld a, >INT_VECT
    ld x, <INT_VECT
    ld b, <int_handler
    ld [a : x], b
    inc x
    ld b, >int_handler
    ld [a : x], b

    ; enable interrupts
    cif

    ; loop filling the screen with one
    ; colour cycling the whole palette
    ld b, 0
loop:
    call fill
    inc b
    and b, 15

    push b
    call draw_sprite
    pop b

    ; wait 1 second
    ld x, 60
wait_loop:
    halt
    dec x
    bnz
    jmp wait_loop

    jmp loop

    ; fill frame-buffer with a color in reg b
fill:
    ld a, 0xbf
    ld x, 0
    ld y, 0x40
fill_loop:
    ld [a : x], b
    inc x
    bno
    jmp fill_loop
    inc a
    dec y
    bnz
    jmp fill_loop
    ret

int_handler:
    iret

draw_sprite:
    ; blitter in settings mode
    ld x, 128
    ld a, 0xb0
    port a, x

    ; setup
    inc a
    ; source
    ld x, <sprite
    port a, x
    ld x, >sprite
    port a, x
    ; destination (56, 56)
    ld x, 56
    port a, x
    port a, x
    ; size 16x16
    ld x, 16
    port a, x
    port a, x

    ; now blit
    dec a
    ld x, 3
    ; 3: write with transparent color support
    port a, x
    ret

sprite:
    .incpng "assets/icon.png"