require'nes'

mappers.NROM()

location(chrrom)

do
    -- nes_ascii.chr: MIT License Copyright (c) 2016 Doug Fraker, www.nesdoug.com
    local f = assert(io.open('nes_ascii.chr', 'rb'))
    local d = f:read('*a') f:close()
    @@chrdata byte(d)
end

location(prgrom)
@@nmi rti
@@irq rti

local hello = "Hello World!"
@@text byte(hello)

@@main
    init()
    --lda#0x80 sta PPUSTAT -- enable VBlank IRQ on NMI vector
    -- load BG palette in PPU RAM
    ppu_addr(BGPAL)
    for _,v in ipairs{ 0x1f, 0x00, 0x10, 0x20 } do lda #v sta PPUIO end
    -- load screen text in PPU RAM 0x21CA
    ppu_addr(0x21ca)
    ldy #0 @_loadtxt lda text,y sta PPUIO iny cpy ##hello bne _loadtxt
    -- reset scroll position
    ppu_addr(0) sta BGSCROL sta BGSCROL
    -- turn screen on
    lda #0x90 sta PPUCNT0 lda #0x1e sta PPUCNT1
    -- idle
    @_loop jmp _loop

writebin(filename..'.nes')
print(stats)