byte ppu_ctrl   @$2000
byte ppu_mask   @$2001
byte ppu_status @$2002
byte oam_addr   @$2003
byte oam_data   @$2004
byte ppu_scroll @$2005
byte ppu_addr   @$2006
byte ppu_data   @$2007
byte oam_dma    @$4014

// TODO: better names

byte apu_pulse1_ctrl       @$4000
byte apu_pulse1_sweep      @$4001
word apu_pulse1_period     @$4002

byte apu_pulse2_ctrl       @$4004
byte apu_pulse2_sweep      @$4005
word apu_pulse2_period     @$4006

byte apu_triangle_unmute   @$4008
word apu_triangle_period   @$400A

byte apu_noise_ctrl        @$400C
byte apu_noise_period      @$400E

byte apu_dmc_ctrl          @$4010
byte apu_dmc_load          @$4011
byte apu_dmc_sample_addr   @$4012
byte apu_dmc_sample_length @$4013

byte apu_status            @$4015
byte apu_frame_counter     @$4017

byte joypad1_ctrl @$4016
byte joypad2_ctrl @$4017

inline asm byte strobe_joypad() {
    ? LDA #1
    STA joypad1_ctrl
    LSR
    STA joypad1_ctrl
    ? RTS
}

inline asm byte read_joypad1() {
    LDA joypad1_ctrl
    ? RTS
}

inline asm byte read_joypad2() {
    LDA joypad2_ctrl
    ? RTS
}

macro asm void simulate_reset() {
    JMP (reset_vector.addr)
}

inline asm void ppu_set_addr(word ax) {
    STX ppu_addr
    STA ppu_addr
    ?RTS
}

inline asm byte read_ppu_status() {
    LDA ppu_status
    ? RTS
}

inline asm void ppu_set_scroll(word a, word x) {
    STA ppu_scroll
    STX ppu_scroll
    ?RTS
}

inline asm void ppu_write_data(byte a) {
    STA ppu_data
    ?RTS
}

inline asm void ppu_oam_dma_write(byte a) {
    STA oam_dma
    ?RTS
}