Remaining serial functions in HOME

4 files changed, 315 insertions, 7 deletions

diff --git a/constants/misc_constants.asm b/constants/misc_constants.asm
index 19deb8e..39f2769 100644
--- a/constants/misc_constants.asm
+++ b/constants/misc_constants.asm
@@ -21,4 +21,8 @@ D_UP       EQU 1 << D_UP_F
 D_DOWN     EQU 1 << D_DOWN_F
 
 BUTTONS    EQU A_BUTTON | B_BUTTON | SELECT | START
-D_PAD      EQU D_RIGHT | D_LEFT | D_UP | D_DOWN
\ No newline at end of file
+D_PAD      EQU D_RIGHT | D_LEFT | D_UP | D_DOWN
+
+; Boolean values
+FALSE EQU 0
+TRUE EQU 1
diff --git a/home/serial.asm b/home/serial.asm
index 48d6832..d51e5a6 100644
--- a/home/serial.asm
+++ b/home/serial.asm
@@ -16,7 +16,7 @@ Serial::
 	ldh a, [hSerialSend]
 	ld [rSB], a
 	ldh a, [hLinkPlayerNumber]
-	cp 2
+	cp USING_INTERNAL_CLOCK
 	jr z, .done
 	ld a, 1 << rSC_ON
 	ld [rSC], a
@@ -26,7 +26,7 @@ Serial::
 	ld a, [rSB]
 	ldh [hSerialReceive], a
 	ldh [hLinkPlayerNumber], a
-	cp 2
+	cp USING_INTERNAL_CLOCK
 	jr z, .master
 	xor a
 	ld [rSB], a
@@ -43,7 +43,7 @@ Serial::
 	xor a
 	ld [rSB], a
 .done
-	ld a, 1
+	ld a, TRUE
 	ldh [hSerialReceived], a
 	ld a, SERIAL_NO_DATA_BYTE
 	ldh [hSerialSend], a
@@ -52,3 +52,296 @@ Serial::
 	pop bc
 	pop af
 	reti
+
+Serial_ExchangeBytes:: ; 64c
+	ld a, $1
+	ldh [hSerialIgnoringInitialData], a
+.loop
+	ld a, [hl]
+	ldh [hSerialSend], a
+	call Serial_ExchangeByte
+	push bc
+	ld b, a
+	inc hl
+	ld a, $30
+.wait
+	dec a
+	jr nz, .wait
+	ldh a, [hSerialIgnoringInitialData]
+	and a
+	ld a, b
+	pop bc
+	jr z, .load
+	dec hl
+	cp SERIAL_PREAMBLE_BYTE
+	jr nz, .loop
+	xor a
+	ldh [hSerialIgnoringInitialData], a
+	jr .loop
+
+.load
+	ld [de], a
+	inc de
+	dec bc
+	ld a, b
+	or c
+	jr nz, .loop
+	ret
+
+Serial_ExchangeByte:: ; 677 (0:0677)
+.loop
+	xor a
+	ldh [hSerialReceived], a
+	ldh a, [hLinkPlayerNumber]
+	cp USING_INTERNAL_CLOCK
+	jr nz, .not_player_2
+	ld a, (1 << rSC_ON) | 1
+	ldh [rSC], a
+.not_player_2
+.loop2
+	ldh a, [hSerialReceived]
+	and a
+	jr nz, .reset_ffca
+	ldh a, [hLinkPlayerNumber]
+	cp $1
+	jr nz, .not_player_1_or_wLinkTimeoutFrames_zero
+	call CheckwLinkTimeoutFramesNonzero
+	jr z, .not_player_1_or_wLinkTimeoutFrames_zero
+	call .delay_15_cycles
+	push hl
+	ld hl, wLinkTimeoutFrames + 1
+	inc [hl]
+	jr nz, .no_rollover_up
+	dec hl
+	inc [hl]
+
+.no_rollover_up
+	pop hl
+	call CheckwLinkTimeoutFramesNonzero
+	jr nz, .loop2
+	jp SerialDisconnected
+
+.not_player_1_or_wLinkTimeoutFrames_zero
+	ldh a, [rIE]
+	and (1 << SERIAL) | (1 << TIMER) | (1 << LCD_STAT) | (1 << VBLANK)
+	cp 1 << SERIAL
+	jr nz, .loop2
+	ld a, [wcb58]
+	dec a
+	ld [wcb58], a
+	jr nz, .loop2
+	ld a, [wcb58 + 1]
+	dec a
+	ld [wcb58 + 1], a
+	jr nz, .loop2
+	ldh a, [hLinkPlayerNumber]
+	cp USING_EXTERNAL_CLOCK
+	jr z, .reset_ffca
+
+	ld a, 255
+.delay_255_cycles
+	dec a
+	jr nz, .delay_255_cycles
+
+.reset_ffca
+	xor a
+	ldh [hSerialReceived], a
+	ldh a, [rIE]
+	and (1 << SERIAL) | (1 << TIMER) | (1 << LCD_STAT) | (1 << VBLANK)
+	sub 1 << SERIAL
+	jr nz, .rIE_not_equal_8
+
+	; LOW($5000)
+	ld [wcb58], a
+	ld a, HIGH($5000)
+	ld [wcb58 + 1], a
+
+.rIE_not_equal_8
+	ldh a, [hSerialReceive]
+	cp SERIAL_NO_DATA_BYTE
+	ret nz
+	call CheckwLinkTimeoutFramesNonzero
+	jr z, .linkTimeoutFrames_zero
+	push hl
+	ld hl, wLinkTimeoutFrames + 1
+	ld a, [hl]
+	dec a
+	ld [hld], a
+	inc a
+	jr nz, .no_rollover
+	dec [hl]
+
+.no_rollover
+	pop hl
+	call CheckwLinkTimeoutFramesNonzero
+	jr z, SerialDisconnected
+
+.linkTimeoutFrames_zero
+	ldh a, [rIE]
+	and (1 << SERIAL) | (1 << TIMER) | (1 << LCD_STAT) | (1 << VBLANK)
+	cp 1 << SERIAL
+	ld a, SERIAL_NO_DATA_BYTE
+	ret z
+	ld a, [hl]
+	ldh [hSerialSend], a
+	call DelayFrame
+	jp .loop
+
+.delay_15_cycles: ; 70e (0:070e)
+	ld a, 15
+.delay_cycles
+	dec a
+	jr nz, .delay_cycles
+	ret
+
+CheckwLinkTimeoutFramesNonzero: ; 714 (0:0714)
+	push hl
+	ld hl, wLinkTimeoutFrames
+	ld a, [hli]
+	or [hl]
+	pop hl
+	ret
+
+SerialDisconnected: ; 71c (0:071c)
+	dec a
+	ld [wLinkTimeoutFrames], a
+	ld [wLinkTimeoutFrames + 1], a
+	ret
+
+; This is used to exchange the button press and selected menu item on the link menu.
+; The data is sent thrice and read twice to increase reliability.
+Serial_ExchangeLinkMenuSelection::
+	ld hl, wPlayerLinkAction
+	ld de, wOtherPlayerLinkMode
+	ld c, 2
+	ld a, TRUE
+	ldh [hSerialIgnoringInitialData], a
+.asm_0730
+	call DelayFrame
+	ld a, [hl]
+	ldh [hSerialSend], a
+	call Serial_ExchangeByte
+	ld b, a
+	inc hl
+	ldh a, [hSerialIgnoringInitialData]
+	and a
+	ld a, FALSE
+	ldh [hSerialIgnoringInitialData], a
+	jr nz, .asm_0730
+	ld a, b
+	ld [de], a
+	inc de
+	dec c
+	jr nz, .asm_0730
+	ret
+
+Serial_PrintWaitingTextAndSyncAndExchangeNybble::
+	call BackUpTilesToBuffer
+	callab PlaceWaitingText
+	call WaitLinkTransfer
+	jp ReloadTilesFromBuffer
+
+WaitLinkTransfer:: ; 75c (0:075c)
+	ld a, $ff
+	ld [wOtherPlayerLinkAction], a
+.loop
+	call LinkTransfer
+	call DelayFrame
+	call CheckwLinkTimeoutFramesNonzero
+	jr z, .check
+	push hl
+	ld hl, wLinkTimeoutFrames + 1
+	dec [hl]
+	jr nz, .skip
+	dec hl
+	dec [hl]
+	jr nz, .skip
+	; We might be disconnected
+	pop hl
+	xor a
+	jp SerialDisconnected
+
+.skip
+	pop hl
+.check
+	ld a, [wOtherPlayerLinkAction]
+	inc a
+	jr z, .loop
+
+	ld b, 10
+.receive
+	call DelayFrame
+	call LinkTransfer
+	dec b
+	jr nz, .receive
+
+	ld b, 10
+.acknowledge
+	call DelayFrame
+	call LinkDataReceived
+	dec b
+	jr nz, .acknowledge
+
+	ld a, [wOtherPlayerLinkAction]
+	ld [wOtherPlayerLinkMode], a
+	ret
+
+LinkTransfer:: ; 7a0 (0:07a0)
+	push bc
+	ld b, $60
+	ld a, [wLinkMode]
+	cp $2
+	jr c, .asm_07ac
+	ld b, $70
+
+.asm_07ac
+	call .Receive
+	ld a, [wPlayerLinkAction]
+	add b
+	ldh [hSerialSend], a
+	ldh a, [hLinkPlayerNumber]
+	cp USING_INTERNAL_CLOCK
+	jr nz, .player_1
+	ld a, (1 << rSC_ON) | 1
+	ldh [rSC], a
+
+.player_1
+	call .Receive
+	pop bc
+	ret
+
+.Receive: ; 7c4 (0:07c4)
+	ldh a, [hSerialReceive]
+	ld [wOtherPlayerLinkMode], a
+	and $f0
+	cp b
+	ret nz
+	xor a
+	ldh [hSerialReceive], a
+	ld a, [wOtherPlayerLinkMode]
+	and $f
+	ld [wOtherPlayerLinkAction], a
+	ret
+
+LinkDataReceived:: ; 7d9 (0:07d9)
+; Let the other system know that the data has been received.
+	xor a
+	ldh [hSerialSend], a
+	ldh a, [hLinkPlayerNumber]
+	cp USING_INTERNAL_CLOCK
+	ret nz
+	ld a, (1 << rSC_ON) | 1
+	ldh [rSC], a
+	ret
+
+Unreferenced_Function7e6::
+	ld a, [wLinkMode]
+	and a
+	ret nz
+	ld a, USING_INTERNAL_CLOCK
+	ldh [rSB], a
+	xor a
+	ldh [hSerialReceive], a
+	ld a, (1 << rSC_ON)
+	ldh [rSC], a
+	ret
diff --git a/hram.asm b/hram.asm
index 977c5b5..5be7909 100644
--- a/hram.asm
+++ b/hram.asm
@@ -114,8 +114,8 @@ hSerialReceived:: ; ffd4
 hLinkPlayerNumber:: ; ffd5
     db
 
-
-    db ; TODO
+hSerialIgnoringInitialData::
+    db
 
 
 hSerialSend:: ; ffd7
diff --git a/wram.asm b/wram.asm
index 01b5cf1..d3c19a0 100644
--- a/wram.asm
+++ b/wram.asm
@@ -207,7 +207,18 @@ wRedrawFlashlightWidthHeight:: db ; cb20
 ; in units of two tiles (people event meta tile)
 ENDU
 
-SECTION "CB56", WRAM0[$CB5B]
+SECTION "CB56", WRAM0[$CB4C]
+wOtherPlayerLinkMode:: db ; cb4c
+wOtherPlayerLinkAction:: db ; cb4d
+	ds 3 ; TODO
+
+wPlayerLinkAction:: db ; cb51
+	ds 4 ; TODO
+
+wLinkTimeoutFrames:: dw ; cb56
+wcb58:: ds 2 ; cb58
+; cb5a
+	ds 1 ; TODO
 wcb5b:: ds 1         ; multipurpose, also wName, wMonDexIndex2
 wNameCategory:: ds 1