Merge commit '60b30c036397cb5627fa374bb930794b225daa29' as 'lib/lufa'

1 files changed, 673 insertions, 0 deletions

diff --git a/lib/lufa/Bootloaders/CDC/BootloaderCDC.c b/lib/lufa/Bootloaders/CDC/BootloaderCDC.c
new file mode 100644
index 000000000..aa17bc15b
--- /dev/null
+++ b/lib/lufa/Bootloaders/CDC/BootloaderCDC.c
@@ -0,0 +1,673 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2017.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2017  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, distribute, and sell this
+  software and its documentation for any purpose is hereby granted
+  without fee, provided that the above copyright notice appear in
+  all copies and that both that the copyright notice and this
+  permission notice and warranty disclaimer appear in supporting
+  documentation, and that the name of the author not be used in
+  advertising or publicity pertaining to distribution of the
+  software without specific, written prior permission.
+
+  The author disclaims all warranties with regard to this
+  software, including all implied warranties of merchantability
+  and fitness.  In no event shall the author be liable for any
+  special, indirect or consequential damages or any damages
+  whatsoever resulting from loss of use, data or profits, whether
+  in an action of contract, negligence or other tortious action,
+  arising out of or in connection with the use or performance of
+  this software.
+*/
+
+/** \file
+ *
+ *  Main source file for the CDC class bootloader. This file contains the complete bootloader logic.
+ */
+
+#define  INCLUDE_FROM_BOOTLOADERCDC_C
+#include "BootloaderCDC.h"
+
+/** Contains the current baud rate and other settings of the first virtual serial port. This must be retained as some
+ *  operating systems will not open the port unless the settings can be set successfully.
+ */
+static CDC_LineEncoding_t LineEncoding = { .BaudRateBPS = 0,
+                                           .CharFormat  = CDC_LINEENCODING_OneStopBit,
+                                           .ParityType  = CDC_PARITY_None,
+                                           .DataBits    = 8                            };
+
+/** Current address counter. This stores the current address of the FLASH or EEPROM as set by the host,
+ *  and is used when reading or writing to the AVRs memory (either FLASH or EEPROM depending on the issued
+ *  command.)
+ */
+static uint32_t CurrAddress;
+
+/** Flag to indicate if the bootloader should be running, or should exit and allow the application code to run
+ *  via a watchdog reset. When cleared the bootloader will exit, starting the watchdog and entering an infinite
+ *  loop until the AVR restarts and the application runs.
+ */
+static bool RunBootloader = true;
+
+/** Magic lock for forced application start. If the HWBE fuse is programmed and BOOTRST is unprogrammed, the bootloader
+ *  will start if the /HWB line of the AVR is held low and the system is reset. However, if the /HWB line is still held
+ *  low when the application attempts to start via a watchdog reset, the bootloader will re-start. If set to the value
+ *  \ref MAGIC_BOOT_KEY the special init function \ref Application_Jump_Check() will force the application to start.
+ */
+uint16_t MagicBootKey ATTR_NO_INIT;
+
+
+/** Special startup routine to check if the bootloader was started via a watchdog reset, and if the magic application
+ *  start key has been loaded into \ref MagicBootKey. If the bootloader started via the watchdog and the key is valid,
+ *  this will force the user application to start via a software jump.
+ */
+void Application_Jump_Check(void)
+{
+	bool JumpToApplication = false;
+
+	#if (BOARD == BOARD_LEONARDO)
+		/* Enable pull-up on the IO13 pin so we can use it to select the mode */
+		PORTC |= (1 << 7);
+		Delay_MS(10);
+
+		/* If IO13 is not jumpered to ground, start the user application instead */
+		JumpToApplication = ((PINC & (1 << 7)) != 0);
+
+		/* Disable pull-up after the check has completed */
+		PORTC &= ~(1 << 7);
+	#elif ((BOARD == BOARD_XPLAIN) || (BOARD == BOARD_XPLAIN_REV1))
+		/* Disable JTAG debugging */
+		JTAG_DISABLE();
+
+		/* Enable pull-up on the JTAG TCK pin so we can use it to select the mode */
+		PORTF |= (1 << 4);
+		Delay_MS(10);
+
+		/* If the TCK pin is not jumpered to ground, start the user application instead */
+		JumpToApplication = ((PINF & (1 << 4)) != 0);
+
+		/* Re-enable JTAG debugging */
+		JTAG_ENABLE();
+	#else
+		/* Check if the device's BOOTRST fuse is set */
+		if (boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS) & FUSE_BOOTRST)
+		{
+			/* If the reset source was not an external reset or the key is correct, clear it and jump to the application */
+			if (!(MCUSR & (1 << EXTRF)) || (MagicBootKey == MAGIC_BOOT_KEY))
+			  JumpToApplication = true;
+
+			/* Clear reset source */
+			MCUSR &= ~(1 << EXTRF);
+		}
+		else
+		{
+			/* If the reset source was the bootloader and the key is correct, clear it and jump to the application;
+			 * this can happen in the HWBE fuse is set, and the HBE pin is low during the watchdog reset */
+			if ((MCUSR & (1 << WDRF)) && (MagicBootKey == MAGIC_BOOT_KEY))
+				JumpToApplication = true;
+
+			/* Clear reset source */
+			MCUSR &= ~(1 << WDRF);
+		}
+	#endif
+
+	/* Don't run the user application if the reset vector is blank (no app loaded) */
+	bool ApplicationValid = (pgm_read_word_near(0) != 0xFFFF);
+
+	/* If a request has been made to jump to the user application, honor it */
+	if (JumpToApplication && ApplicationValid)
+	{
+		/* Turn off the watchdog */
+		MCUSR &= ~(1 << WDRF);
+		wdt_disable();
+
+		/* Clear the boot key and jump to the user application */
+		MagicBootKey = 0;
+
+		// cppcheck-suppress constStatement
+		((void (*)(void))0x0000)();
+	}
+}
+
+/** Main program entry point. This routine configures the hardware required by the bootloader, then continuously
+ *  runs the bootloader processing routine until instructed to soft-exit, or hard-reset via the watchdog to start
+ *  the loaded application code.
+ */
+int main(void)
+{
+	/* Setup hardware required for the bootloader */
+	SetupHardware();
+
+	/* Turn on first LED on the board to indicate that the bootloader has started */
+	LEDs_SetAllLEDs(LEDS_LED1);
+
+	/* Enable global interrupts so that the USB stack can function */
+	GlobalInterruptEnable();
+
+	while (RunBootloader)
+	{
+		CDC_Task();
+		USB_USBTask();
+	}
+
+	/* Wait a short time to end all USB transactions and then disconnect */
+	_delay_us(1000);
+
+	/* Disconnect from the host - USB interface will be reset later along with the AVR */
+	USB_Detach();
+
+	/* Unlock the forced application start mode of the bootloader if it is restarted */
+	MagicBootKey = MAGIC_BOOT_KEY;
+
+	/* Enable the watchdog and force a timeout to reset the AVR */
+	wdt_enable(WDTO_250MS);
+
+	for (;;);
+}
+
+/** Configures all hardware required for the bootloader. */
+static void SetupHardware(void)
+{
+	/* Disable watchdog if enabled by bootloader/fuses */
+	MCUSR &= ~(1 << WDRF);
+	wdt_disable();
+
+	/* Disable clock division */
+	clock_prescale_set(clock_div_1);
+
+	/* Relocate the interrupt vector table to the bootloader section */
+	MCUCR = (1 << IVCE);
+	MCUCR = (1 << IVSEL);
+
+	/* Initialize the USB and other board hardware drivers */
+	USB_Init();
+	LEDs_Init();
+
+	/* Bootloader active LED toggle timer initialization */
+	TIMSK1 = (1 << TOIE1);
+	TCCR1B = ((1 << CS11) | (1 << CS10));
+}
+
+/** ISR to periodically toggle the LEDs on the board to indicate that the bootloader is active. */
+ISR(TIMER1_OVF_vect, ISR_BLOCK)
+{
+	LEDs_ToggleLEDs(LEDS_LED1 | LEDS_LED2);
+}
+
+/** Event handler for the USB_ConfigurationChanged event. This configures the device's endpoints ready
+ *  to relay data to and from the attached USB host.
+ */
+void EVENT_USB_Device_ConfigurationChanged(void)
+{
+	/* Setup CDC Notification, Rx and Tx Endpoints */
+	Endpoint_ConfigureEndpoint(CDC_NOTIFICATION_EPADDR, EP_TYPE_INTERRUPT,
+	                           CDC_NOTIFICATION_EPSIZE, 1);
+
+	Endpoint_ConfigureEndpoint(CDC_TX_EPADDR, EP_TYPE_BULK, CDC_TXRX_EPSIZE, 1);
+
+	Endpoint_ConfigureEndpoint(CDC_RX_EPADDR, EP_TYPE_BULK, CDC_TXRX_EPSIZE, 1);
+}
+
+/** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to
+ *  the device from the USB host before passing along unhandled control requests to the library for processing
+ *  internally.
+ */
+void EVENT_USB_Device_ControlRequest(void)
+{
+	/* Ignore any requests that aren't directed to the CDC interface */
+	if ((USB_ControlRequest.bmRequestType & (CONTROL_REQTYPE_TYPE | CONTROL_REQTYPE_RECIPIENT)) !=
+	    (REQTYPE_CLASS | REQREC_INTERFACE))
+	{
+		return;
+	}
+
+	/* Activity - toggle indicator LEDs */
+	LEDs_ToggleLEDs(LEDS_LED1 | LEDS_LED2);
+
+	/* Process CDC specific control requests */
+	switch (USB_ControlRequest.bRequest)
+	{
+		case CDC_REQ_GetLineEncoding:
+			if (USB_ControlRequest.bmRequestType == (REQDIR_DEVICETOHOST | REQTYPE_CLASS | REQREC_INTERFACE))
+			{
+				Endpoint_ClearSETUP();
+
+				/* Write the line coding data to the control endpoint */
+				Endpoint_Write_Control_Stream_LE(&LineEncoding, sizeof(CDC_LineEncoding_t));
+				Endpoint_ClearOUT();
+			}
+
+			break;
+		case CDC_REQ_SetLineEncoding:
+			if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE))
+			{
+				Endpoint_ClearSETUP();
+
+				/* Read the line coding data in from the host into the global struct */
+				Endpoint_Read_Control_Stream_LE(&LineEncoding, sizeof(CDC_LineEncoding_t));
+				Endpoint_ClearIN();
+			}
+
+			break;
+        case CDC_REQ_SetControlLineState:
+	        if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE))
+	        {
+	            Endpoint_ClearSETUP();
+	            Endpoint_ClearStatusStage();
+	        }
+
+	        break;
+	}
+}
+
+#if !defined(NO_BLOCK_SUPPORT)
+/** Reads or writes a block of EEPROM or FLASH memory to or from the appropriate CDC data endpoint, depending
+ *  on the AVR109 protocol command issued.
+ *
+ *  \param[in] Command  Single character AVR109 protocol command indicating what memory operation to perform
+ */
+static void ReadWriteMemoryBlock(const uint8_t Command)
+{
+	uint16_t BlockSize;
+	char     MemoryType;
+
+	uint8_t  HighByte = 0;
+	uint8_t  LowByte  = 0;
+
+	BlockSize  = (FetchNextCommandByte() << 8);
+	BlockSize |=  FetchNextCommandByte();
+
+	MemoryType =  FetchNextCommandByte();
+
+	if ((MemoryType != MEMORY_TYPE_FLASH) && (MemoryType != MEMORY_TYPE_EEPROM))
+	{
+		/* Send error byte back to the host */
+		WriteNextResponseByte('?');
+
+		return;
+	}
+
+	/* Check if command is to read a memory block */
+	if (Command == AVR109_COMMAND_BlockRead)
+	{
+		/* Re-enable RWW section */
+		boot_rww_enable();
+
+		while (BlockSize--)
+		{
+			if (MemoryType == MEMORY_TYPE_FLASH)
+			{
+				/* Read the next FLASH byte from the current FLASH page */
+				#if (FLASHEND > 0xFFFF)
+				WriteNextResponseByte(pgm_read_byte_far(CurrAddress | HighByte));
+				#else
+				WriteNextResponseByte(pgm_read_byte(CurrAddress | HighByte));
+				#endif
+
+				/* If both bytes in current word have been read, increment the address counter */
+				if (HighByte)
+				  CurrAddress += 2;
+
+				HighByte = !HighByte;
+			}
+			else
+			{
+				/* Read the next EEPROM byte into the endpoint */
+				WriteNextResponseByte(eeprom_read_byte((uint8_t*)(intptr_t)(CurrAddress >> 1)));
+
+				/* Increment the address counter after use */
+				CurrAddress += 2;
+			}
+		}
+	}
+	else
+	{
+		uint32_t PageStartAddress = CurrAddress;
+
+		if (MemoryType == MEMORY_TYPE_FLASH)
+		{
+			boot_page_erase(PageStartAddress);
+			boot_spm_busy_wait();
+		}
+
+		while (BlockSize--)
+		{
+			if (MemoryType == MEMORY_TYPE_FLASH)
+			{
+				/* If both bytes in current word have been written, increment the address counter */
+				if (HighByte)
+				{
+					/* Write the next FLASH word to the current FLASH page */
+					boot_page_fill(CurrAddress, ((FetchNextCommandByte() << 8) | LowByte));
+
+					/* Increment the address counter after use */
+					CurrAddress += 2;
+				}
+				else
+				{
+					LowByte = FetchNextCommandByte();
+				}
+
+				HighByte = !HighByte;
+			}
+			else
+			{
+				/* Write the next EEPROM byte from the endpoint */
+				eeprom_update_byte((uint8_t*)((intptr_t)(CurrAddress >> 1)), FetchNextCommandByte());
+
+				/* Increment the address counter after use */
+				CurrAddress += 2;
+			}
+		}
+
+		/* If in FLASH programming mode, commit the page after writing */
+		if (MemoryType == MEMORY_TYPE_FLASH)
+		{
+			/* Commit the flash page to memory */
+			boot_page_write(PageStartAddress);
+
+			/* Wait until write operation has completed */
+			boot_spm_busy_wait();
+		}
+
+		/* Send response byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+}
+#endif
+
+/** Retrieves the next byte from the host in the CDC data OUT endpoint, and clears the endpoint bank if needed
+ *  to allow reception of the next data packet from the host.
+ *
+ *  \return Next received byte from the host in the CDC data OUT endpoint
+ */
+static uint8_t FetchNextCommandByte(void)
+{
+	/* Select the OUT endpoint so that the next data byte can be read */
+	Endpoint_SelectEndpoint(CDC_RX_EPADDR);
+
+	/* If OUT endpoint empty, clear it and wait for the next packet from the host */
+	while (!(Endpoint_IsReadWriteAllowed()))
+	{
+		Endpoint_ClearOUT();
+
+		while (!(Endpoint_IsOUTReceived()))
+		{
+			if (USB_DeviceState == DEVICE_STATE_Unattached)
+			  return 0;
+		}
+	}
+
+	/* Fetch the next byte from the OUT endpoint */
+	return Endpoint_Read_8();
+}
+
+/** Writes the next response byte to the CDC data IN endpoint, and sends the endpoint back if needed to free up the
+ *  bank when full ready for the next byte in the packet to the host.
+ *
+ *  \param[in] Response  Next response byte to send to the host
+ */
+static void WriteNextResponseByte(const uint8_t Response)
+{
+	/* Select the IN endpoint so that the next data byte can be written */
+	Endpoint_SelectEndpoint(CDC_TX_EPADDR);
+
+	/* If IN endpoint full, clear it and wait until ready for the next packet to the host */
+	if (!(Endpoint_IsReadWriteAllowed()))
+	{
+		Endpoint_ClearIN();
+
+		while (!(Endpoint_IsINReady()))
+		{
+			if (USB_DeviceState == DEVICE_STATE_Unattached)
+			  return;
+		}
+	}
+
+	/* Write the next byte to the IN endpoint */
+	Endpoint_Write_8(Response);
+}
+
+/** Task to read in AVR109 commands from the CDC data OUT endpoint, process them, perform the required actions
+ *  and send the appropriate response back to the host.
+ */
+static void CDC_Task(void)
+{
+	/* Select the OUT endpoint */
+	Endpoint_SelectEndpoint(CDC_RX_EPADDR);
+
+	/* Check if endpoint has a command in it sent from the host */
+	if (!(Endpoint_IsOUTReceived()))
+	  return;
+
+	/* Read in the bootloader command (first byte sent from host) */
+	uint8_t Command = FetchNextCommandByte();
+
+	if (Command == AVR109_COMMAND_ExitBootloader)
+	{
+		RunBootloader = false;
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if ((Command == AVR109_COMMAND_SetLED) || (Command == AVR109_COMMAND_ClearLED) ||
+	         (Command == AVR109_COMMAND_SelectDeviceType))
+	{
+		FetchNextCommandByte();
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if ((Command == AVR109_COMMAND_EnterProgrammingMode) || (Command == AVR109_COMMAND_LeaveProgrammingMode))
+	{
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if (Command == AVR109_COMMAND_ReadPartCode)
+	{
+		/* Return ATMEGA128 part code - this is only to allow AVRProg to use the bootloader */
+		WriteNextResponseByte(0x44);
+		WriteNextResponseByte(0x00);
+	}
+	else if (Command == AVR109_COMMAND_ReadAutoAddressIncrement)
+	{
+		/* Indicate auto-address increment is supported */
+		WriteNextResponseByte('Y');
+	}
+	else if (Command == AVR109_COMMAND_SetCurrentAddress)
+	{
+		/* Set the current address to that given by the host (translate 16-bit word address to byte address) */
+		CurrAddress   = (FetchNextCommandByte() << 9);
+		CurrAddress  |= (FetchNextCommandByte() << 1);
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if (Command == AVR109_COMMAND_ReadBootloaderInterface)
+	{
+		/* Indicate serial programmer back to the host */
+		WriteNextResponseByte('S');
+	}
+	else if (Command == AVR109_COMMAND_ReadBootloaderIdentifier)
+	{
+		/* Write the 7-byte software identifier to the endpoint */
+		for (uint8_t CurrByte = 0; CurrByte < 7; CurrByte++)
+		  WriteNextResponseByte(SOFTWARE_IDENTIFIER[CurrByte]);
+	}
+	else if (Command == AVR109_COMMAND_ReadBootloaderSWVersion)
+	{
+		WriteNextResponseByte('0' + BOOTLOADER_VERSION_MAJOR);
+		WriteNextResponseByte('0' + BOOTLOADER_VERSION_MINOR);
+	}
+	else if (Command == AVR109_COMMAND_ReadSignature)
+	{
+		WriteNextResponseByte(AVR_SIGNATURE_3);
+		WriteNextResponseByte(AVR_SIGNATURE_2);
+		WriteNextResponseByte(AVR_SIGNATURE_1);
+	}
+	else if (Command == AVR109_COMMAND_EraseFLASH)
+	{
+		/* Clear the application section of flash */
+		for (uint32_t CurrFlashAddress = 0; CurrFlashAddress < (uint32_t)BOOT_START_ADDR; CurrFlashAddress += SPM_PAGESIZE)
+		{
+			boot_page_erase(CurrFlashAddress);
+			boot_spm_busy_wait();
+			boot_page_write(CurrFlashAddress);
+			boot_spm_busy_wait();
+		}
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	#if !defined(NO_LOCK_BYTE_WRITE_SUPPORT)
+	else if (Command == AVR109_COMMAND_WriteLockbits)
+	{
+		/* Set the lock bits to those given by the host */
+		boot_lock_bits_set(FetchNextCommandByte());
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	#endif
+	else if (Command == AVR109_COMMAND_ReadLockbits)
+	{
+		WriteNextResponseByte(boot_lock_fuse_bits_get(GET_LOCK_BITS));
+	}
+	else if (Command == AVR109_COMMAND_ReadLowFuses)
+	{
+		WriteNextResponseByte(boot_lock_fuse_bits_get(GET_LOW_FUSE_BITS));
+	}
+	else if (Command == AVR109_COMMAND_ReadHighFuses)
+	{
+		WriteNextResponseByte(boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS));
+	}
+	else if (Command == AVR109_COMMAND_ReadExtendedFuses)
+	{
+		WriteNextResponseByte(boot_lock_fuse_bits_get(GET_EXTENDED_FUSE_BITS));
+	}
+	#if !defined(NO_BLOCK_SUPPORT)
+	else if (Command == AVR109_COMMAND_GetBlockWriteSupport)
+	{
+		WriteNextResponseByte('Y');
+
+		/* Send block size to the host */
+		WriteNextResponseByte(SPM_PAGESIZE >> 8);
+		WriteNextResponseByte(SPM_PAGESIZE & 0xFF);
+	}
+	else if ((Command == AVR109_COMMAND_BlockWrite) || (Command == AVR109_COMMAND_BlockRead))
+	{
+		/* Delegate the block write/read to a separate function for clarity */
+		ReadWriteMemoryBlock(Command);
+	}
+	#endif
+	#if !defined(NO_FLASH_BYTE_SUPPORT)
+	else if (Command == AVR109_COMMAND_FillFlashPageWordHigh)
+	{
+		/* Write the high byte to the current flash page */
+		boot_page_fill(CurrAddress, FetchNextCommandByte());
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if (Command == AVR109_COMMAND_FillFlashPageWordLow)
+	{
+		/* Write the low byte to the current flash page */
+		boot_page_fill(CurrAddress | 0x01, FetchNextCommandByte());
+
+		/* Increment the address */
+		CurrAddress += 2;
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if (Command == AVR109_COMMAND_WriteFlashPage)
+	{
+		/* Commit the flash page to memory */
+		boot_page_write(CurrAddress);
+
+		/* Wait until write operation has completed */
+		boot_spm_busy_wait();
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if (Command == AVR109_COMMAND_ReadFLASHWord)
+	{
+		#if (FLASHEND > 0xFFFF)
+		uint16_t ProgramWord = pgm_read_word_far(CurrAddress);
+		#else
+		uint16_t ProgramWord = pgm_read_word(CurrAddress);
+		#endif
+
+		WriteNextResponseByte(ProgramWord >> 8);
+		WriteNextResponseByte(ProgramWord & 0xFF);
+	}
+	#endif
+	#if !defined(NO_EEPROM_BYTE_SUPPORT)
+	else if (Command == AVR109_COMMAND_WriteEEPROM)
+	{
+		/* Read the byte from the endpoint and write it to the EEPROM */
+		eeprom_update_byte((uint8_t*)((intptr_t)(CurrAddress >> 1)), FetchNextCommandByte());
+
+		/* Increment the address after use */
+		CurrAddress += 2;
+
+		/* Send confirmation byte back to the host */
+		WriteNextResponseByte('\r');
+	}
+	else if (Command == AVR109_COMMAND_ReadEEPROM)
+	{
+		/* Read the EEPROM byte and write it to the endpoint */
+		WriteNextResponseByte(eeprom_read_byte((uint8_t*)((intptr_t)(CurrAddress >> 1))));
+
+		/* Increment the address after use */
+		CurrAddress += 2;
+	}
+	#endif
+	else if (Command != AVR109_COMMAND_Sync)
+	{
+		/* Unknown (non-sync) command, return fail code */
+		WriteNextResponseByte('?');
+	}
+
+	/* Select the IN endpoint */
+	Endpoint_SelectEndpoint(CDC_TX_EPADDR);
+
+	/* Remember if the endpoint is completely full before clearing it */
+	bool IsEndpointFull = !(Endpoint_IsReadWriteAllowed());
+
+	/* Send the endpoint data to the host */
+	Endpoint_ClearIN();
+
+	/* If a full endpoint's worth of data was sent, we need to send an empty packet afterwards to signal end of transfer */
+	if (IsEndpointFull)
+	{
+		while (!(Endpoint_IsINReady()))
+		{
+			if (USB_DeviceState == DEVICE_STATE_Unattached)
+			  return;
+		}
+
+		Endpoint_ClearIN();
+	}
+
+	/* Wait until the data has been sent to the host */
+	while (!(Endpoint_IsINReady()))
+	{
+		if (USB_DeviceState == DEVICE_STATE_Unattached)
+		  return;
+	}
+
+	/* Select the OUT endpoint */
+	Endpoint_SelectEndpoint(CDC_RX_EPADDR);
+
+	/* Acknowledge the command from the host */
+	Endpoint_ClearOUT();
+}