INCLUDE "hardware.inc"
INCLUDE "game/game.asm"
INCLUDE "tools.asm"

SECTION "Header", ROM0[$100]

EntryPoint: ;
    di ; Disable interrupts. That way we can avoid dealing with them, especially since we didn't talk about them yet
    jp Start ; Leave this tiny space

REPT $150 - $104
    db 0
ENDR

SECTION "Intro code", ROM0

Start:
    ; First step is to access the VRAM to insert our graphics data.
    ; To do so, we must wait until we are in VBLANK period.
    ; Loop until we find ourselves in VBLANK

    ; Turn off the LCD
.waitVBlank
    ld a, [rLY] ; Load the current vertical line being rendered
    cp 144 ; Check if we're past VBlank (1 to 144 = carry bit set)
    jr c, .waitVBlank ; Jump back to waitVBlank if rLY is less than 144

    xor a ; ld a, 0 ; Reset the accumilator register
    ; Our target is to set bit 7 reset on the LDC to turn it off
    ld [rLCDC], a ; We will have to write to LCDC again later, so it's not a bother, really.

; ----------- Font Begin copying to VRAM -----------
    ; Start copying our font to vram
    ld de, FontTiles ; The start of the font tiles
    ld hl, $9000 ; Set registers hl to $9000 which is the beginning of vram
    ld bc, FontTilesEnd - FontTiles ; The total length of font tiles
    call Memcpy

; ----------- Begin copying string to palette -----------
    ld hl, $9800 ; This will print the string at the top-left corner of screen
    ld de, HelloWorldStr
.copyString
    ld a, [de] ; Read the first byte in the string to accumilator
    ld [hli], a ; Write the byte from the accumilator to the destination while incrementing destination address
    inc de ; Move to next byte in string
    and a ; AND a with A, Checking if we copied a zero (end of string)
    jr nz, .copyString ; Continue copying while not zero

; ----------- Start the display -----------
    ; Init the display register
    ld a, %11100100 ; Load the palette of white, light gray, dark gray, black
    ld a, %00011011 ; Load the palette of white, light gray, dark gray, black
    ld [rBGP], a ; Store the palette to display

    xor a ; ld a, 0 ; Reset the accumilator
    ld [rSCY], a ; Set our scroll Y position to 0
    ld [rSCX], a ; Set our scroll X position to 0

    ld [rNR52], a ; Turn off sound

    ; Turn the screen on, display background
    ld a, %10000001 ; screen on = 8th bit, background display = 1st bit
    ld [rLCDC], a ; Set the screen flags
    jp GameLoop

SECTION "Font", ROM0

FontTiles:
INCBIN "font.chr"
FontTilesEnd:

Section "Hello wrold string", ROM0

HelloWorldStr:
    db "Hello World!", 0