ref: c1daafe7416db04d8bdbb8f9ccc2f455b9d421c3
dir: /engine/printer/printer_serial.asm/
Printer_StartTransmission: ld hl, wGameboyPrinterRAM ld bc, wGameboyPrinterRAMEnd - wGameboyPrinterRAM xor a call Printer_ByteFill xor a ldh [rSB], a ldh [rSC], a ld [wPrinterOpcode], a ld hl, wPrinterConnectionOpen set 0, [hl] ld a, [wGBPrinter] ld [wGBPrinterSettings], a xor a ld [wJumptableIndex], a ret PrinterJumptableIteration: ld a, [wJumptableIndex] ld e, a ld d, 0 ld hl, .Jumptable add hl, de add hl, de ld a, [hli] ld h, [hl] ld l, a jp hl .Jumptable: dw Print_InitPrinterHandshake ; 00 dw Printer_CheckConnectionStatus ; 01 dw Printer_WaitSerial ; 02 dw Printer_StartTransmittingTilemap ; 03 dw Printer_TransmissionLoop ; 04 dw Printer_WaitSerialAndLoopBack2 ; 05 dw Printer_EndTilemapTransmission ; 06 dw Printer_TransmissionLoop ; 07 dw Printer_WaitSerial ; 08 dw Printer_SignalSendHeader ; 09 dw Printer_TransmissionLoop ; 0a dw Printer_WaitSerial ; 0b dw Printer_WaitUntilFinished ; 0c dw Printer_Quit ; 0d dw Printer_NextSection ; 0e dw Printer_WaitSerial ; 0f dw Printer_SignalLoopBack ; 10 dw Printer_SectionOne ; 11 dw Printer_NextSectionWaitLoopBack ; 12 dw Printer_WaitLoopBack ; 13 _Printer_NextSection: ld hl, wJumptableIndex inc [hl] ret Printer_PrevSection: ld hl, wJumptableIndex dec [hl] ret Printer_Quit: xor a ld [wPrinterStatusFlags], a ld hl, wJumptableIndex set 7, [hl] ret Printer_NextSection: call _Printer_NextSection ret Printer_SectionOne: ld a, $1 ld [wJumptableIndex], a ret Print_InitPrinterHandshake: call Printer_ResetData ld hl, PrinterDataPacket1 call Printer_CopyPacket xor a ld [wPrinterSendByteCounter], a ld [wPrinterSendByteCounter + 1], a ld a, [wPrinterQueueLength] ld [wPrinterRowIndex], a call _Printer_NextSection call Printer_WaitHandshake ld a, PRINTER_STATUS_CHECKING ld [wPrinterStatus], a ret Printer_StartTransmittingTilemap: call Printer_ResetData ; check ??? ld hl, wPrinterRowIndex ld a, [hl] and a jr z, Printer_EndTilemapTransmission ; send packet 3 ld hl, PrinterDataPacket3 ; signal start of transmission call Printer_CopyPacket ; prepare to send 40 tiles call Printer_Convert2RowsTo2bpp ld a, LOW(40 tiles) ld [wPrinterSendByteCounter], a ld a, HIGH(40 tiles) ld [wPrinterSendByteCounter + 1], a ; compute the checksum call Printer_ComputeChecksum call _Printer_NextSection call Printer_WaitHandshake ld a, PRINTER_STATUS_TRANSMITTING ld [wPrinterStatus], a ret Printer_EndTilemapTransmission: ; ensure that we go from here to routine 7 ld a, $6 ld [wJumptableIndex], a ; send packet 4 ld hl, PrinterDataPacket4 ; signal no transmission call Printer_CopyPacket ; send no tile data xor a ld [wPrinterSendByteCounter], a ld [wPrinterSendByteCounter + 1], a call _Printer_NextSection call Printer_WaitHandshake ret Printer_SignalSendHeader: call Printer_ResetData ld hl, PrinterDataPacket2 ; signal request print call Printer_CopyPacket ; prepare to send 1 tile call Printer_StageHeaderForSend ld a, LOW(4) ld [wPrinterSendByteCounter], a ld a, HIGH(4) ld [wPrinterSendByteCounter + 1], a ; compute the checksum call Printer_ComputeChecksum call _Printer_NextSection call Printer_WaitHandshake ld a, PRINTER_STATUS_PRINTING ld [wPrinterStatus], a ret Printer_SignalLoopBack: call Printer_ResetData ; send packet 1 ld hl, PrinterDataPacket1 ; signal no transmission call Printer_CopyPacket ; send no tile data xor a ld [wPrinterSendByteCounter], a ld [wPrinterSendByteCounter + 1], a ld a, [wPrinterQueueLength] ld [wPrinterRowIndex], a call _Printer_NextSection call Printer_WaitHandshake ret Printer_WaitSerial: ld hl, wPrinterSerialFrameDelay inc [hl] ld a, [hl] cp $6 ret c xor a ld [hl], a call _Printer_NextSection ret Printer_WaitSerialAndLoopBack2: ld hl, wPrinterSerialFrameDelay inc [hl] ld a, [hl] cp $6 ret c xor a ld [hl], a ld hl, wPrinterRowIndex dec [hl] call Printer_PrevSection call Printer_PrevSection ret Printer_CheckConnectionStatus: ld a, [wPrinterOpcode] and a ret nz ld a, [wPrinterHandshake] cp $ff jr nz, .printer_connected ld a, [wPrinterStatusFlags] cp $ff jr z, .printer_error .printer_connected ld a, [wPrinterHandshake] cp $81 jr nz, .printer_error ld a, [wPrinterStatusFlags] cp $0 jr nz, .printer_error ld hl, wPrinterConnectionOpen set 1, [hl] ld a, $5 ld [wHandshakeFrameDelay], a call _Printer_NextSection ret .printer_error ld a, $ff ld [wPrinterHandshake], a ld [wPrinterStatusFlags], a ld a, $e ld [wJumptableIndex], a ret Printer_TransmissionLoop: ld a, [wPrinterOpcode] and a ret nz ld a, [wPrinterStatusFlags] and $f0 jr nz, .enter_wait_loop ld a, [wPrinterStatusFlags] and $1 jr nz, .cycle_back call _Printer_NextSection ret .cycle_back call Printer_PrevSection ret .enter_wait_loop ld a, $12 ; Printer_NextSectionWaitLoopBack ld [wJumptableIndex], a ret Printer_WaitUntilFinished: ld a, [wPrinterOpcode] and a ret nz ld a, [wPrinterStatusFlags] and $f3 ret nz call _Printer_NextSection ret Printer_NextSectionWaitLoopBack: call _Printer_NextSection Printer_WaitLoopBack: ld a, [wPrinterOpcode] and a ret nz ld a, [wPrinterStatusFlags] and $f0 ret nz xor a ld [wJumptableIndex], a ret Printer_WaitHandshake: .loop ld a, [wPrinterOpcode] and a jr nz, .loop xor a ld [wPrinterSendByteOffset], a ld [wPrinterSendByteOffset + 1], a ld a, $1 ld [wPrinterOpcode], a ld a, $88 ldh [rSB], a ld a, $1 ldh [rSC], a ld a, $81 ldh [rSC], a ret Printer_CopyPacket: ld a, [hli] ld [wPrinterData], a ld a, [hli] ld [wPrinterData + 1], a ld a, [hli] ld [wPrinterData + 2], a ld a, [hli] ld [wPrinterData + 3], a ld a, [hli] ld [wPrinterChecksum], a ld a, [hl] ld [wPrinterChecksum + 1], a ret Printer_ResetData: xor a ld hl, wPrinterData ld [hli], a ld [hli], a ld [hli], a ld [hl], a ld hl, wPrinterChecksum ld [hli], a ld [hl], a xor a ld [wPrinterSendByteCounter], a ld [wPrinterSendByteCounter + 1], a ld hl, wGameboyPrinterRAM ld bc, wGameboyPrinter2bppSourceEnd - wGameboyPrinter2bppSource call Printer_ByteFill ret Printer_ComputeChecksum: ld hl, 0 ld bc, 4 ld de, wPrinterData call .ComputeChecksum ld a, [wPrinterSendByteCounter] ld c, a ld a, [wPrinterSendByteCounter + 1] ld b, a ld de, wGameboyPrinterRAM call .ComputeChecksum ld a, l ld [wPrinterChecksum], a ld a, h ld [wPrinterChecksum + 1], a ret .ComputeChecksum: .loop ld a, [de] inc de add l jr nc, .no_overflow inc h .no_overflow ld l, a dec bc ld a, c or b jr nz, .loop ret Printer_StageHeaderForSend: ld a, $1 ld [wGameboyPrinter2bppSource + 0], a ld a, [wcbfa] ld [wGameboyPrinter2bppSource + 1], a ld a, %11100100 ld [wGameboyPrinter2bppSource + 2], a ld a, [wGBPrinterSettings] ld [wGameboyPrinter2bppSource + 3], a ret Printer_Convert2RowsTo2bpp: ; de = wPrinterTileMapBuffer + 2 * SCREEN_WIDTH * ([wPrinterQueueLength] - [wPrinterRowIndex]) ld a, [wPrinterRowIndex] xor $ff ld d, a ld a, [wPrinterQueueLength] inc a add d ld hl, wPrinterTileMapBuffer ld de, 2 * SCREEN_WIDTH .loop1 and a jr z, .okay1 add hl, de dec a jr .loop1 .okay1 ld e, l ld d, h ld hl, wGameboyPrinter2bppSource ld c, 2 * SCREEN_WIDTH .loop2 ld a, [de] inc de push bc push de push hl ; convert tile index to vram address swap a ld d, a and $f0 ld e, a ld a, d and $f ld d, a and $8 ld a, d jr nz, .vtiles_8xxx or $90 jr .got_vtile_addr .vtiles_8xxx or $80 .got_vtile_addr ld d, a ; copy 1 vtile to hl lb bc, BANK(Printer_Convert2RowsTo2bpp), 1 call Request2bpp pop hl ld de, 1 tiles add hl, de pop de pop bc dec c jr nz, .loop2 ret Printer_ByteFill: push de ld e, a .loop ld [hl], e inc hl dec bc ld a, c or b jr nz, .loop ld a, e pop de ret PrinterDataPacket1: db 1, 0, $00, 0 dw 1 PrinterDataPacket2: db 2, 0, $04, 0 dw 0 PrinterDataPacket3: db 4, 0, $80, 2 dw 0 PrinterDataPacket4: db 4, 0, $00, 0 dw 4 PrinterDataPacket5: ; unused db 8, 0, $00, 0 dw 8 PrinterDataPacket6: ; unused db 15, 0, $00, 0 dw 15 _PrinterReceive:: ld a, [wPrinterOpcode] add a ld e, a ld d, 0 ld hl, .Jumptable add hl, de ld a, [hli] ld h, [hl] ld l, a jp hl .Jumptable: dw Printer_DoNothing ; 00 dw Printer_Send0x33 ; 01 dw Printer_SendPrinterData1 ; 02 dw Printer_SendPrinterData2 ; 03 dw Printer_SendPrinterData3 ; 04 dw Printer_SendPrinterData4 ; 05 dw Printer_SendNextByte ; 06 dw Printer_SendwPrinterChecksumLo ; 07 dw Printer_SendwPrinterChecksumHi ; 08 dw Printer_Send0x00_2 ; 09 dw Printer_ReceiveTwoPrinterHandshakeAndSend0x00 ; 0a dw Printer_ReceiveTwoPrinterStatusFlagsAndExitSendLoop ; 0b dw Printer_Send0x33 ; 0c triggered by AskSerial dw Printer_Send0x0f ; 0d dw Printer_Send0x00 ; 0e dw Printer_Send0x00 ; 0f dw Printer_Send0x00 ; 10 dw Printer_Send0x0f ; 11 dw Printer_Send0x00 ; 12 dw Printer_Send0x00_2 ; 13 dw Printer_ReceiveTwoPrinterHandshakeAndSend0x00 ; 14 dw Printer_ReceiveTwoPrinterStatusFlagsAndExitSendLoop_2 ; 15 dw Printer_Send0x33 ; 16 triggered by pressing B dw Printer_Send0x08 ; 17 dw Printer_Send0x00 ; 18 dw Printer_Send0x00 ; 19 dw Printer_Send0x00 ; 1a dw Printer_Send0x08 ; 1b dw Printer_Send0x00 ; 1c dw Printer_Send0x00_2 ; 1d dw Printer_ReceiveTwoPrinterHandshakeAndSend0x00 ; 1e dw Printer_ReceiveTwoPrinterStatusFlagsAndExitSendLoop ; 1f Printer_NextInstruction: ld hl, wPrinterOpcode inc [hl] ret Printer_DoNothing: ret Printer_Send0x33: ld a, $33 call Printer_SerialSend call Printer_NextInstruction ret Printer_SendPrinterData1: ld a, [wPrinterData] call Printer_SerialSend call Printer_NextInstruction ret Printer_SendPrinterData2: ld a, [wPrinterData + 1] call Printer_SerialSend call Printer_NextInstruction ret Printer_SendPrinterData3: ld a, [wPrinterData + 2] call Printer_SerialSend call Printer_NextInstruction ret Printer_SendPrinterData4: ld a, [wPrinterData + 3] call Printer_SerialSend call Printer_NextInstruction ret Printer_SendNextByte: ; decrement 16-bit counter ld hl, wPrinterSendByteCounter ld a, [hli] ld d, [hl] ld e, a or d jr z, .done dec de ld [hl], d dec hl ld [hl], e ld a, [wPrinterSendByteOffset] ld e, a ld a, [wPrinterSendByteOffset + 1] ld d, a ld hl, wGameboyPrinterRAM add hl, de inc de ld a, e ld [wPrinterSendByteOffset], a ld a, d ld [wPrinterSendByteOffset + 1], a ld a, [hl] call Printer_SerialSend ret .done call Printer_NextInstruction Printer_SendwPrinterChecksumLo: ld a, [wPrinterChecksum] call Printer_SerialSend call Printer_NextInstruction ret Printer_SendwPrinterChecksumHi: ld a, [wPrinterChecksum + 1] call Printer_SerialSend call Printer_NextInstruction ret Printer_Send0x00_2: ; identical to Printer_Send0x00, but referenced less ld a, $0 call Printer_SerialSend call Printer_NextInstruction ret Printer_ReceiveTwoPrinterHandshakeAndSend0x00: ldh a, [rSB] ld [wPrinterHandshake], a ld a, $0 call Printer_SerialSend call Printer_NextInstruction ret Printer_ReceiveTwoPrinterStatusFlagsAndExitSendLoop: ldh a, [rSB] ld [wPrinterStatusFlags], a xor a ld [wPrinterOpcode], a ret Printer_Send0x0f: ld a, $f call Printer_SerialSend call Printer_NextInstruction ret Printer_Send0x00: ld a, $0 call Printer_SerialSend call Printer_NextInstruction ret Printer_Send0x08: ld a, $8 call Printer_SerialSend call Printer_NextInstruction ret Printer_SerialSend: ldh [rSB], a ld a, $1 ; switch to internal clock ldh [rSC], a ld a, $81 ; start transfer ldh [rSC], a ret Printer_ReceiveTwoPrinterStatusFlagsAndExitSendLoop_2: ; identical to Printer_ReceiveTwoPrinterStatusFlagsAndExitSendLoop, but referenced less ldh a, [rSB] ld [wPrinterStatusFlags], a xor a ld [wPrinterOpcode], a ret