PUSHS "Sound Variables", WRAM0[AUDIO_VARS_START]
ordersStart: dw
println "orders start is ", ordersStart
ordersLength: db


; audio player state
currentOrderNumber: db
currentRowNumber: db
println "currentRowNumber is ", currentRowNumber
currentTickNumber: db
currentPattern: dw
println "current pattern is ", currentPattern
audioReadHead: dw

AUDIO_VARIABLES_BEGIN:

speed: db

macro channel ; macro to define all the channell data in parallel
channel_\1_note: db
channel_\1_duty: db
channel_\1_volume: db
channel_\1_slide: db
channel_\1_arp: db
channel_\1_pan: db
channel_\1_vibrato: db
channel_\1_trigger: db
endm

channel 1
channel 2
channel 3
channel 4

println "channel 1 note is ", channel_1_note
AUDIO_VARIABLES_END:
POPS

SoundSetup:
  ld a, LOW(gbtarottheme)
  ld [ordersStart], a 
  ld a, HIGH(gbtarottheme)
  ld [ordersStart+1], a 
  
  ld a, 0
  ld [currentOrderNumber], a 
  ld [currentRowNumber], a 
  ld [currentTickNumber], a
  
  ld a, $FF
  ld [currentRowNumber], a 
  
  ld a, [ordersStart]
  ld l, a 
  ld a, [ordersStart+1]
  ld h, a 
  inc hl 
  
  ld a, [hl+]
  ld [currentPattern], a 
  ld [audioReadHead], a 
  ld a, [hl+]
  ld [currentPattern+1], a 
  ld [audioReadHead+1], a
  
  ld hl, ZEROES
  ld de, AUDIO_VARIABLES_BEGIN
  ld bc, AUDIO_VARIABLES_END - AUDIO_VARIABLES_BEGIN
  call CopyRange
  
  ld a, 6 
  ld [speed], a 
  
  ld a, %1000_1111
  ld [rNR52], a
  ld a, $ff
  ld [rNR51], a 
  ld a, $11
  ld [rNR50], a 
  
  ret
SoundUpdate:
  ld a, [speed]
  ld b, a 
  ld a, [currentTickNumber]
  inc a
  call ArrayClampLoopingB
  ld [currentTickNumber], a 
  
  cp a, 0 
  jp nz, .doneAllPackets ; if we're not zero, then just update the things
  
  ld b, 64
  ld a, [currentRowNumber]
  inc a 
  call ArrayClampLoopingB
  ld [currentRowNumber], a 
  
  cp a, 0
  jp nz, :+ ; if the new row number is zero, then we go to the next pattern.
  ld a, AUDHIGH_RESTART
  ld [rNR14], a


  ; TODO: update for song orders
  ld a, [currentPattern]
  ld [audioReadHead], a 
  ld a, [currentPattern+1]
  ld [audioReadHead+1], a 
:
  ld a, [audioReadHead]
  ld l, a 
  ld a, [audioReadHead+1]
  ld h, a 
  
  ld a, [currentRowNumber]
  ld b, a 
  ld a, [hl+]
  and a, $F0
  cp a, 0
  ret nz
  ld a, [hl+]
  cp a, b
  jp nz, .doneAllPackets ; return if the current row doesn't equal the row we're looking at 
  
  ; else we're looking at packets
.packetExamine
  ld a, l 
  ld [audioReadHead], a 
  ld a, h 
  ld [audioReadHead+1], a
  
  ld d, h
  ld e, l 
  
  ld hl, channel_1_note
  
  ld a, [de]
  and a, $0F
  cp a, 1
  jp nz, :+
  ld hl, channel_1_note
: cp a, 2
  jp nz, :+
  ld hl, channel_2_note
: cp a, 3
  jp nz, :+
  ld hl, channel_3_note
: cp a, 4
  jp nz, :+
  ld hl, channel_4_note
:
  
  ld a, [de]
  and a, $F0 ; grab the top nibble of [hl], which holds the effect.
  
  ; if nibble is zero, then update our read head (already done) and return.
  cp a, $00 
  jp z, .doneAllPackets
  
  ld bc, channel_1_note - channel_1_note
  cp a, $10
  jp z, .updateValue
  
  ld bc, channel_1_volume - channel_1_note
  cp a, $20
  jp z, .updateVolume
  
  ld bc, channel_1_duty - channel_1_note
  cp a, $30
  jp z, .updateValue
  
  ld bc, channel_1_pan - channel_1_note
  cp a, $40
  jp z, .updateValue
  
  ld bc, channel_1_arp - channel_1_note
  cp a, $50
  jp z, .updateValue
  
  ld bc, channel_1_vibrato - channel_1_note
  cp a, $60
  jp z, .updateValue
  
  ld bc, channel_1_slide - channel_1_note
  cp a, $70
  jp z, .updateValue
  
  ld bc, channel_1_volume - channel_1_note
  cp a, $80
  jp z, .noteCut
  
  cp a, $90
  jp z, .patternJump
  
  cp a, $a0
  jp z, .breakSetStep
  
  cp a, $b0
  jp z, .setSpeed
  
  cp a, $c0
  jp z, .event
  ; and now a bunch of code for handling all those cases!

.updateVolume:
  inc de
  add hl, bc
  ld a, 0 
  ld [channel_1_trigger], a
  ld a, [hl]
  cp a, 0
  jp nz, :+
  ; if the volume is zero to start with,
  ; and the new volume is nonzero,
  ld a, [de]
  ; set the trigger flag
  cp a, 0
  jp z, :+
  ld a, AUDHIGH_RESTART
  ld [channel_1_trigger], a
:

  ld a, [de]
  ld [hl], a 
  
  inc de
  ld h, d 
  ld l, e
  jp .packetExamine
  
.updateValue:
  inc de 
  
  add hl, bc 
: ld a, [de]
  ld [hl], a
  
  inc de
  ld h, d 
  ld l, e
  
  jp .packetExamine
  
.noteCut:
  inc de
  add hl, bc
  
  ld [hl], 0
  
  ld a, AUDHIGH_RESTART
  ld [channel_1_trigger], a
  
  inc de
  ld h, d
  ld l, e 
  jp .packetExamine
.patternJump:
  ; TODO
  inc de
  inc de
  ld h, d
  ld l, e 
  jp .packetExamine
.breakSetStep:
  ; TODO
  inc de
  inc de
  ld h, d
  ld l, e 
  jp .packetExamine
.setSpeed:
  inc de 
  ld a, [de]
  ld [speed], a 
  
  inc de 
  ld h, d
  ld l, e 
  jp .packetExamine
.event:
  ; TODO
  inc de
  inc de
  ld h, d
  ld l, e 
  jp .packetExamine
  

.doneAllPackets:
  call Channel_1_Update
  call Channel_2_Update
  call Channel_3_Update
  call Channel_4_Update
  ret
  
  
Channel_1_Update:
  ld a, [channel_1_duty]
  or a, $0a
  ld [rNR11], a 
  
  ld a, [channel_1_volume]
  sla a 
  sla a 
  sla a
  sla a
  and a, $F0
  ld [rNR12], a
  
  ld a, [channel_1_note]
  ld hl, note_periods
  ld b, 0 
  ld c, a 
  add hl, bc
  add hl, bc ; double width values
  
  ld a, [hl+]
  ld [rNR13], a 
  
  
  ld a, [channel_1_trigger]
  or a, [hl]
  or a, AUDHIGH_LENGTH_OFF
  ld [rNR14], a 
  
  ld a, 0 
  ld [channel_1_trigger], a
  ret 
  
Channel_2_Update:
Channel_3_Update:
Channel_4_Update:
  ret

note_periods:
  dw 44, 156, 262, 363, 457, 547, 631, 710, 786, 854, 923, 986, ; C3 to B3
  dw 1046,1102,1155,1205,1253,1297,1339,1379,1417,1452,1486,1517, ; C4 to B4
  dw 1546,1575,1602,1627,1650,1673,1694,1714,1732,1750,1767,1783, ; C5 to B5
  dw 1798,1812,1825,1837,1849,1860,1871,1881,1890,1899,1907,1915, ; C6 to B6
  dw 1923,1930,1936,1943,1949,1954,1959,1964,1969,1974,1978,1982, ; C7 to B7
  dw 1985,1988,1992,1995,1998,2001,2004,2006,2009,2011,2013,2015  ; C8 to B8

INCLUDE "theme.inc"