.define PSG $7f
.define PAGING_REGISTER $ffff
.define BANK_START $8000
.define BANK_END $c000
.define LOOKUP_TABLE_BASE $3800
.define CONTROLLER_PORT_A $dc
.define CONTROLLER_1_BUTTON_1 %00010000
.define CONTROLLER_1_BUTTON_2 %00100000

PlaySample: ; $36db
; Arguments:
; hl = data
; d = delay paramter (higher = lower sample rate)
    di ; Stop interrupts
    call SilencePSG

    ; Set tones to 0
    ld a, %10000000 ; Channel 0 tone 0
    out (PSG), a
    xor a
    out (PSG), a
    ld a, %10100000 ; Channel 1 tone 0
    out (PSG), a 
    xor a
    out (PSG), a
    ld a, %11000000 ; Channel 2 tone 0
    out (PSG), a 
    xor a
    out (PSG), a

    ; Transfer data pointer to hl' and pre-decrement it
    push hl
    exx
      pop hl
      dec hl
    exx

    ; Delay proportional to d
    ld e, d
--: ld a, $ff
-:  dec a
    jr nz, -
    dec e
    jr nz, --

    ; Set tones to %1111110001 = $3f1 = 110Hz
    ; This seems unnecessary...
    ld e, %00111111
    ld a, %10000001 ; Channel 0
    out (PSG), a
    ld a, e
    out (PSG), a
    ld a, %10100001 ; Channel 1
    out (PSG), a 
    ld a, e
    out (PSG), a
    ld a, %11000001 ; Channel 2
    out (PSG), a 
    ld a, e
    out (PSG), a

-:  ; Main sample loop
    ; Set tones to %0000000101 = $005
    ld e, %00000000
    ld a, %10000101 ; Channel 0
    out (PSG), a
    ld a, e
    out (PSG), a 
    ld a, %10100101 ; Channel 1
    out (PSG), a
    ld a, e
    out (PSG), a
    ld a, %11100101 ; Channel 2
    out (PSG), a
    ld a, e
    out (PSG), a
    exx
      inc hl ; Next sample
      ld a, <BANK_END ; Check if we got to the end of the bank
      cp h 
      ld a, (hl) ; Get the sample
      jr nz, + ; If not at the end of the bank, we are done
      push af
        ld a, ($d3dc)
        inc a ; 
        ld ($d3dc), a
        ld (PAGING_REGISTER), a
        ld hl, BANK_START
        ld a, (hl) ; re-get sample
      pop af
+:  exx

    ; Look up the three PSG data values to use for the sample value
    ld h, <LOOKUP_TABLE_BASE
    ld l, a ; Index by sample
    ld a, (hl) ; Get adjustment value
    out (PSG), a
    inc h ; Next section of the lookup
    ld a, (hl)
    out (PSG), a
    inc h ; And again
    ld a, (hl)
    out (PSG), a

    ; Read the cotrollers and OR button 1 or 2 into this RAM location
    ld a, ($d20a) 
    ld e, a
    in a, (CONTROLLER_PORT_A) ; Read the controllers
    cpl ; Invert so 1 = pressed
    and CONTROLLER_1_BUTTON_1  CONTROLLER_1_BUTTON_2
    or e
    ld ($d20a), a

    ld e, d ; Delay
-:  dec e
    jr nz, -

    dec bc ; Decrement byte counter
    ld a, b
    or c
    jr nz, - ; Loop until it reaches 0
    ; Then fall through and return

SilencePSG: ; $376d
    ld a, %10111111 ; Channel 1 volume f
    out (PSG),a
    ld a, %11011111 ; Channel 2 volume f
    out (PSG), a
    ld a, %11111111 ; Channel 3 volume f
    out (PSG), a
    ld a, %10011111 ; Channel 0 volume f
    out (PSG), a
    ret

Laugh: ; $377E
    ld d, $14 ; Rate
    ld a, $0d ; Bank ($34000)
    ld (PAGING_REGISTER), a
    di
-:  ld hl, $8000 ; Sample 1 at $34000
    ld bc, $0811 ; Length
    push de
      call PlaySample
    pop de
    inc d ; Slow down playback
    inc d
    ld a, d
    cp $1c
    jr nz, - ; And repeat slower

    ld hl, $8bf9 ; Sample 2 at $34bf9
    ld bc, $0e62 ; Length
    ld d, $1e ; Rate
    call PlaySample
    ret