Move out the Mass Storage class bootloader to the main Bootloader directory now that it is functional.

4 files changed, 818 insertions, 0 deletions

diff --git a/Bootloaders/MassStorage/Lib/SCSI.c b/Bootloaders/MassStorage/Lib/SCSI.c
new file mode 100644
index 000000000..154fe4885
--- /dev/null
+++ b/Bootloaders/MassStorage/Lib/SCSI.c
@@ -0,0 +1,319 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2013.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2013  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
+ *
+ *  SCSI command processing routines, for SCSI commands issued by the host. Mass Storage
+ *  devices use a thin "Bulk-Only Transport" protocol for issuing commands and status information,
+ *  which wrap around standard SCSI device commands for controlling the actual storage medium.
+ */
+
+#define  INCLUDE_FROM_SCSI_C
+#include "SCSI.h"
+
+/** Structure to hold the SCSI response data to a SCSI INQUIRY command. This gives information about the device's
+ *  features and capabilities.
+ */
+static const SCSI_Inquiry_Response_t InquiryData =
+	{
+		.DeviceType          = DEVICE_TYPE_BLOCK,
+		.PeripheralQualifier = 0,
+
+		.Removable           = true,
+
+		.Version             = 0,
+
+		.ResponseDataFormat  = 2,
+		.NormACA             = false,
+		.TrmTsk              = false,
+		.AERC                = false,
+
+		.AdditionalLength    = 0x1F,
+
+		.SoftReset           = false,
+		.CmdQue              = false,
+		.Linked              = false,
+		.Sync                = false,
+		.WideBus16Bit        = false,
+		.WideBus32Bit        = false,
+		.RelAddr             = false,
+
+		.VendorID            = "LUFA",
+		.ProductID           = "Bootloader",
+		.RevisionID          = {'0','.','0','0'},
+	};
+
+/** Structure to hold the sense data for the last issued SCSI command, which is returned to the host after a SCSI REQUEST SENSE
+ *  command is issued. This gives information on exactly why the last command failed to complete.
+ */
+static SCSI_Request_Sense_Response_t SenseData =
+	{
+		.ResponseCode        = 0x70,
+		.AdditionalLength    = 0x0A,
+	};
+
+
+/** Main routine to process the SCSI command located in the Command Block Wrapper read from the host. This dispatches
+ *  to the appropriate SCSI command handling routine if the issued command is supported by the device, else it returns
+ *  a command failure due to a ILLEGAL REQUEST.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to the Mass Storage class interface structure that the command is associated with
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise
+ */
+bool SCSI_DecodeSCSICommand(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo)
+{
+	bool CommandSuccess = false;
+
+	/* Run the appropriate SCSI command hander function based on the passed command */
+	switch (MSInterfaceInfo->State.CommandBlock.SCSICommandData[0])
+	{
+		case SCSI_CMD_INQUIRY:
+			CommandSuccess = SCSI_Command_Inquiry(MSInterfaceInfo);
+			break;
+		case SCSI_CMD_REQUEST_SENSE:
+			CommandSuccess = SCSI_Command_Request_Sense(MSInterfaceInfo);
+			break;
+		case SCSI_CMD_READ_CAPACITY_10:
+			CommandSuccess = SCSI_Command_Read_Capacity_10(MSInterfaceInfo);
+			break;
+		case SCSI_CMD_SEND_DIAGNOSTIC:
+			CommandSuccess = SCSI_Command_Send_Diagnostic(MSInterfaceInfo);
+			break;
+		case SCSI_CMD_WRITE_10:
+			CommandSuccess = SCSI_Command_ReadWrite_10(MSInterfaceInfo, DATA_WRITE);
+			break;
+		case SCSI_CMD_READ_10:
+			CommandSuccess = SCSI_Command_ReadWrite_10(MSInterfaceInfo, DATA_READ);
+			break;
+		case SCSI_CMD_MODE_SENSE_6:
+			CommandSuccess = SCSI_Command_ModeSense_6(MSInterfaceInfo);
+			break;
+		case SCSI_CMD_START_STOP_UNIT:
+		case SCSI_CMD_TEST_UNIT_READY:
+		case SCSI_CMD_PREVENT_ALLOW_MEDIUM_REMOVAL:
+		case SCSI_CMD_VERIFY_10:
+			/* These commands should just succeed, no handling required */
+			CommandSuccess = true;
+			MSInterfaceInfo->State.CommandBlock.DataTransferLength = 0;
+			break;
+		default:
+			/* Update the SENSE key to reflect the invalid command */
+			SCSI_SET_SENSE(SCSI_SENSE_KEY_ILLEGAL_REQUEST,
+		                   SCSI_ASENSE_INVALID_COMMAND,
+		                   SCSI_ASENSEQ_NO_QUALIFIER);
+			break;
+	}
+
+	/* Check if command was successfully processed */
+	if (CommandSuccess)
+	{
+		SCSI_SET_SENSE(SCSI_SENSE_KEY_GOOD,
+		               SCSI_ASENSE_NO_ADDITIONAL_INFORMATION,
+		               SCSI_ASENSEQ_NO_QUALIFIER);
+
+		return true;
+	}
+
+	return false;
+}
+
+/** Command processing for an issued SCSI INQUIRY command. This command returns information about the device's features
+ *  and capabilities to the host.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to the Mass Storage class interface structure that the command is associated with
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise.
+ */
+static bool SCSI_Command_Inquiry(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo)
+{
+	uint16_t AllocationLength  = SwapEndian_16(*(uint16_t*)&MSInterfaceInfo->State.CommandBlock.SCSICommandData[3]);
+	uint16_t BytesTransferred  = MIN(AllocationLength, sizeof(InquiryData));
+
+	/* Only the standard INQUIRY data is supported, check if any optional INQUIRY bits set */
+	if ((MSInterfaceInfo->State.CommandBlock.SCSICommandData[1] & ((1 << 0) | (1 << 1))) ||
+	     MSInterfaceInfo->State.CommandBlock.SCSICommandData[2])
+	{
+		/* Optional but unsupported bits set - update the SENSE key and fail the request */
+		SCSI_SET_SENSE(SCSI_SENSE_KEY_ILLEGAL_REQUEST,
+		               SCSI_ASENSE_INVALID_FIELD_IN_CDB,
+		               SCSI_ASENSEQ_NO_QUALIFIER);
+
+		return false;
+	}
+
+	Endpoint_Write_Stream_LE(&InquiryData, BytesTransferred, NULL);
+
+	/* Pad out remaining bytes with 0x00 */
+	Endpoint_Null_Stream((AllocationLength - BytesTransferred), NULL);
+
+	/* Finalize the stream transfer to send the last packet */
+	Endpoint_ClearIN();
+
+	/* Succeed the command and update the bytes transferred counter */
+	MSInterfaceInfo->State.CommandBlock.DataTransferLength -= BytesTransferred;
+
+	return true;
+}
+
+/** Command processing for an issued SCSI REQUEST SENSE command. This command returns information about the last issued command,
+ *  including the error code and additional error information so that the host can determine why a command failed to complete.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to the Mass Storage class interface structure that the command is associated with
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise.
+ */
+static bool SCSI_Command_Request_Sense(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo)
+{
+	uint8_t AllocationLength = MSInterfaceInfo->State.CommandBlock.SCSICommandData[4];
+	uint8_t BytesTransferred = MIN(AllocationLength, sizeof(SenseData));
+
+	Endpoint_Write_Stream_LE(&SenseData, BytesTransferred, NULL);
+	Endpoint_Null_Stream((AllocationLength - BytesTransferred), NULL);
+	Endpoint_ClearIN();
+
+	/* Succeed the command and update the bytes transferred counter */
+	MSInterfaceInfo->State.CommandBlock.DataTransferLength -= BytesTransferred;
+
+	return true;
+}
+
+/** Command processing for an issued SCSI READ CAPACITY (10) command. This command returns information about the device's capacity
+ *  on the selected Logical Unit (drive), as a number of OS-sized blocks.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to the Mass Storage class interface structure that the command is associated with
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise.
+ */
+static bool SCSI_Command_Read_Capacity_10(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo)
+{
+	uint32_t LastBlockAddressInLUN = (LUN_MEDIA_BLOCKS - 1);
+	uint32_t MediaBlockSize        = SECTOR_SIZE_BYTES;
+
+	Endpoint_Write_Stream_BE(&LastBlockAddressInLUN, sizeof(LastBlockAddressInLUN), NULL);
+	Endpoint_Write_Stream_BE(&MediaBlockSize, sizeof(MediaBlockSize), NULL);
+	Endpoint_ClearIN();
+
+	/* Succeed the command and update the bytes transferred counter */
+	MSInterfaceInfo->State.CommandBlock.DataTransferLength -= 8;
+
+	return true;
+}
+
+/** Command processing for an issued SCSI SEND DIAGNOSTIC command. This command performs a quick check of the Dataflash ICs on the
+ *  board, and indicates if they are present and functioning correctly. Only the Self-Test portion of the diagnostic command is
+ *  supported.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to the Mass Storage class interface structure that the command is associated with
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise.
+ */
+static bool SCSI_Command_Send_Diagnostic(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo)
+{
+	/* Check to see if the SELF TEST bit is not set */
+	if (!(MSInterfaceInfo->State.CommandBlock.SCSICommandData[1] & (1 << 2)))
+	{
+		/* Only self-test supported - update SENSE key and fail the command */
+		SCSI_SET_SENSE(SCSI_SENSE_KEY_ILLEGAL_REQUEST,
+		               SCSI_ASENSE_INVALID_FIELD_IN_CDB,
+		               SCSI_ASENSEQ_NO_QUALIFIER);
+
+		return false;
+	}
+
+	/* Succeed the command and update the bytes transferred counter */
+	MSInterfaceInfo->State.CommandBlock.DataTransferLength = 0;
+
+	return true;
+}
+
+/** Command processing for an issued SCSI READ (10) or WRITE (10) command. This command reads in the block start address
+ *  and total number of blocks to process, then calls the appropriate low-level Dataflash routine to handle the actual
+ *  reading and writing of the data.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to the Mass Storage class interface structure that the command is associated with
+ *  \param[in] IsDataRead  Indicates if the command is a READ (10) command or WRITE (10) command (DATA_READ or DATA_WRITE)
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise.
+ */
+static bool SCSI_Command_ReadWrite_10(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo,
+                                      const bool IsDataRead)
+{
+	uint32_t BlockAddress;
+	uint16_t TotalBlocks;
+
+	/* Load in the 32-bit block address (SCSI uses big-endian, so have to reverse the byte order) */
+	BlockAddress = SwapEndian_32(*(uint32_t*)&MSInterfaceInfo->State.CommandBlock.SCSICommandData[2]);
+
+	/* Load in the 16-bit total blocks (SCSI uses big-endian, so have to reverse the byte order) */
+	TotalBlocks  = SwapEndian_16(*(uint16_t*)&MSInterfaceInfo->State.CommandBlock.SCSICommandData[7]);
+
+	/* Check if the block address is outside the maximum allowable value for the LUN */
+	if (BlockAddress >= LUN_MEDIA_BLOCKS)
+	{
+		/* Block address is invalid, update SENSE key and return command fail */
+		SCSI_SET_SENSE(SCSI_SENSE_KEY_ILLEGAL_REQUEST,
+		               SCSI_ASENSE_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE,
+		               SCSI_ASENSEQ_NO_QUALIFIER);
+
+		return false;
+	}
+
+	/* Determine if the packet is a READ (10) or WRITE (10) command, call appropriate function */
+	if (IsDataRead == DATA_READ)
+	  VirtualFAT_ReadBlocks(MSInterfaceInfo, BlockAddress, TotalBlocks);
+	else
+	  VirtualFAT_WriteBlocks(MSInterfaceInfo, BlockAddress, TotalBlocks);
+
+	/* Update the bytes transferred counter and succeed the command */
+	MSInterfaceInfo->State.CommandBlock.DataTransferLength -= ((uint32_t)TotalBlocks * SECTOR_SIZE_BYTES);
+
+	return true;
+}
+
+/** Command processing for an issued SCSI MODE SENSE (6) command. This command returns various informational pages about
+ *  the SCSI device, as well as the device's Write Protect status.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to the Mass Storage class interface structure that the command is associated with
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise.
+ */
+static bool SCSI_Command_ModeSense_6(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo)
+{
+	/* Send an empty header response indicating Write Protect flag is off */
+	Endpoint_Write_32_LE(0);
+	Endpoint_ClearIN();
+
+	/* Update the bytes transferred counter and succeed the command */
+	MSInterfaceInfo->State.CommandBlock.DataTransferLength -= 4;
+
+	return true;
+}
+
diff --git a/Bootloaders/MassStorage/Lib/SCSI.h b/Bootloaders/MassStorage/Lib/SCSI.h
new file mode 100644
index 000000000..54914f5eb
--- /dev/null
+++ b/Bootloaders/MassStorage/Lib/SCSI.h
@@ -0,0 +1,85 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2013.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2013  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
+ *
+ *  Header file for SCSI.c.
+ */
+
+#ifndef _SCSI_H_
+#define _SCSI_H_
+
+	/* Includes: */
+		#include <avr/io.h>
+		#include <avr/pgmspace.h>
+
+		#include <LUFA/Drivers/USB/USB.h>
+
+		#include "../BootloaderMassStorage.h"
+		#include "../Descriptors.h"
+		#include "VirtualFAT.h"
+
+	/* Macros: */
+		/** Macro to set the current SCSI sense data to the given key, additional sense code and additional sense qualifier. This
+		 *  is for convenience, as it allows for all three sense values (returned upon request to the host to give information about
+		 *  the last command failure) in a quick and easy manner.
+		 *
+		 *  \param[in] Key    New SCSI sense key to set the sense code to
+		 *  \param[in] Acode  New SCSI additional sense key to set the additional sense code to
+		 *  \param[in] Aqual  New SCSI additional sense key qualifier to set the additional sense qualifier code to
+		 */
+		#define SCSI_SET_SENSE(Key, Acode, Aqual)  MACROS{ SenseData.SenseKey                 = (Key);   \
+		                                                   SenseData.AdditionalSenseCode      = (Acode); \
+		                                                   SenseData.AdditionalSenseQualifier = (Aqual); }MACROE
+
+		/** Macro for the \ref SCSI_Command_ReadWrite_10() function, to indicate that data is to be read from the storage medium. */
+		#define DATA_READ           true
+
+		/** Macro for the \ref SCSI_Command_ReadWrite_10() function, to indicate that data is to be written to the storage medium. */
+		#define DATA_WRITE          false
+
+		/** Value for the DeviceType entry in the SCSI_Inquiry_Response_t enum, indicating a Block Media device. */
+		#define DEVICE_TYPE_BLOCK   0x00
+
+	/* Function Prototypes: */
+		bool SCSI_DecodeSCSICommand(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo);
+
+		#if defined(INCLUDE_FROM_SCSI_C)
+			static bool SCSI_Command_Inquiry(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo);
+			static bool SCSI_Command_Request_Sense(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo);
+			static bool SCSI_Command_Read_Capacity_10(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo);
+			static bool SCSI_Command_Send_Diagnostic(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo);
+			static bool SCSI_Command_ReadWrite_10(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo,
+			                                      const bool IsDataRead);
+			static bool SCSI_Command_ModeSense_6(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo);
+		#endif
+
+#endif
+
diff --git a/Bootloaders/MassStorage/Lib/VirtualFAT.c b/Bootloaders/MassStorage/Lib/VirtualFAT.c
new file mode 100644
index 000000000..0bcda0620
--- /dev/null
+++ b/Bootloaders/MassStorage/Lib/VirtualFAT.c
@@ -0,0 +1,255 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2013.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2013  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
+ *
+ *  Virtualized FAT12 filesystem implementation, to perform self-programming
+ *  in response to read and write requests to the virtual filesystem by the
+ *  host PC.
+ */
+
+#define  INCLUDE_FROM_VIRTUAL_FAT_C
+#include "VirtualFAT.h"
+
+/** FAT filesystem boot sector block, must be the first sector on the physical
+ *  disk so that the host can identify the presence of a FAT filesystem. This
+ *  block is truncated; normally a large bootstrap section is located near the
+ *  end of the block for booting purposes however as this is not meant to be a
+ *  bootable disk it is omitted for space reasons.
+ *
+ *  \note When returning the boot block to the host, the magic signature 0xAA55
+ *        must be added to the very end of the block to identify it as a boot
+ *        block.
+ */
+static const FATBootBlock_t BootBlock =
+	{
+		.Bootstrap               = {0xEB, 0x3C, 0x90},
+		.Description             = "mkdosfs",
+		.SectorSize              = SECTOR_SIZE_BYTES,
+		.SectorsPerCluster       = SECTOR_PER_CLUSTER,
+		.ReservedSectors         = 1,
+		.FATCopies               = 2,
+		.RootDirectoryEntries    = (SECTOR_SIZE_BYTES / sizeof(FATDirectoryEntry_t)),
+		.TotalSectors16          = LUN_MEDIA_BLOCKS,
+		.MediaDescriptor         = 0xF8,
+		.SectorsPerFAT           = 1,
+		.SectorsPerTrack         = (LUN_MEDIA_BLOCKS % 64),
+		.Heads                   = (LUN_MEDIA_BLOCKS / 64),
+		.HiddenSectors           = 0,
+		.TotalSectors32          = 0,
+		.PhysicalDriveNum        = 0,
+		.ExtendedBootRecordSig   = 0x29,
+		.VolumeSerialNumber      = 0x12345678,
+		.VolumeLabel             = "LUFA BOOT  ",
+		.FilesystemIdentifier    = "FAT12   ",
+	};
+
+/** FAT 8.3 style directory entry, for the virtual FLASH contents file. */
+static FATDirectoryEntry_t FirmwareFileEntry =
+	{
+		.Filename               = "FIRMWARE",
+		.Extension              = "BIN",
+		.Attributes             = 0,
+		.Reserved               = {0},
+		.CreationTime           = FAT_TIME(1, 1, 0),
+		.CreationDate           = FAT_DATE(14, 2, 1989),
+		.StartingCluster        = 2,
+		.FileSizeBytes          = FIRMWARE_FILE_SIZE_BYTES,
+	};
+
+
+/** Updates a FAT12 cluster entry in the FAT file table with the specified next
+ *  chain index. If the cluster is the last in the file chain, the magic value
+ *  0xFFF is used.
+ *
+ *  \note FAT data cluster indexes are offset by 2, so that cluster 2 is the
+ *        first file data cluster on the disk. See the FAT specification.
+ *
+ *  \param[out]  FATTable    Pointer to the FAT12 allocation table
+ *  \param[in]   Index       Index of the cluster entry to update
+ *  \param[in]   ChainEntry  Next cluster index in the file chain
+ */
+static void UpdateFAT12ClusterEntry(uint8_t* const FATTable,
+                                    const uint16_t Index,
+                                    const uint16_t ChainEntry)
+{
+	/* Calculate the starting offset of the cluster entry in the FAT12 table */
+	uint8_t FATOffset   =   (Index * 3) / 2;
+	bool    UpperNibble = (((Index * 3) % 2) != 0);
+
+	/* Check if the start of the entry is at an upper nibble of the byte, fill
+	 * out FAT12 entry as required */
+	if (UpperNibble)
+	{
+		FATTable[FATOffset]     = (FATTable[FATOffset] & 0x0F) | ((ChainEntry & 0x0F) << 4);
+		FATTable[FATOffset + 1] = (ChainEntry >> 4);
+	}
+	else
+	{
+		FATTable[FATOffset]     = ChainEntry;
+		FATTable[FATOffset + 1] = (FATTable[FATOffset] & 0xF0) | (ChainEntry >> 8);
+	}
+}
+
+/** Writes a block of data to the virtual FAT filesystem, from the USB Mass
+ *  Storage interface.
+ *
+ *  \param[in]  BlockNumber  Index of the block to write.
+ */
+static void WriteVirtualBlock(const uint16_t BlockNumber)
+{
+	uint8_t BlockBuffer[SECTOR_SIZE_BYTES];
+
+	/* Buffer the entire block to be written from the host */
+	Endpoint_Read_Stream_LE(BlockBuffer, sizeof(BlockBuffer), NULL);
+	Endpoint_ClearOUT();
+
+	if ((BlockNumber >= 4) && (BlockNumber < (4 + FILE_SECTORS(FIRMWARE_FILE_SIZE_BYTES))))
+	{
+		uint32_t WriteFlashAddress = (uint32_t)(BlockNumber - 4) * SECTOR_SIZE_BYTES;
+
+		for (uint16_t i = 0; i < SECTOR_SIZE_BYTES; i += 2)
+		{
+			if ((WriteFlashAddress % SPM_PAGESIZE) == 0)
+			{
+				/* Erase the given FLASH page, ready to be programmed */
+				boot_page_erase(WriteFlashAddress);
+				boot_spm_busy_wait();
+			}
+
+			/* Write the next data word to the FLASH page */
+			boot_page_fill(WriteFlashAddress, (BlockBuffer[i + 1] << 8) | BlockBuffer[i]);
+			WriteFlashAddress += 2;
+
+			if ((WriteFlashAddress % SPM_PAGESIZE) == 0)
+			{
+				/* Write the filled FLASH page to memory */
+				boot_page_write(WriteFlashAddress - SPM_PAGESIZE);
+				boot_spm_busy_wait();
+			}
+		}
+	}
+}
+
+/** Reads a block of data from the virtual FAT filesystem, and sends it to the
+ *  host via the USB Mass Storage interface.
+ *
+ *  \param[in]  BlockNumber  Index of the block to read.
+ */
+static void ReadVirtualBlock(const uint16_t BlockNumber)
+{
+	uint8_t BlockBuffer[SECTOR_SIZE_BYTES];
+	memset(BlockBuffer, 0x00, sizeof(BlockBuffer));
+
+	switch (BlockNumber)
+	{
+		case 0: /* Block 0: Boot block sector */
+			memcpy(BlockBuffer, &BootBlock, sizeof(FATBootBlock_t));
+
+			/* Add the magic signature to the end of the block */
+			BlockBuffer[SECTOR_SIZE_BYTES - 2] = 0x55;
+			BlockBuffer[SECTOR_SIZE_BYTES - 1] = 0xAA;
+			break;
+
+		case 1: /* Block 1: First FAT12 cluster chain copy */
+		case 2: /* Block 2: Second FAT12 cluster chain copy */
+			/* Cluster 0: Media type/Reserved */
+			UpdateFAT12ClusterEntry(BlockBuffer, 0, 0xF00 | BootBlock.MediaDescriptor);
+
+			/* Cluster 1: Reserved */
+			UpdateFAT12ClusterEntry(BlockBuffer, 1, 0xFFF);
+
+			/* Cluster 2 onwards: Cluster chain of FIRMWARE.BIN */
+			for (uint16_t i = 0; i < FILE_CLUSTERS(FIRMWARE_FILE_SIZE_BYTES); i++)
+			  UpdateFAT12ClusterEntry(BlockBuffer, i+2, i+3);
+
+			/* Mark last cluster as end of file */
+			UpdateFAT12ClusterEntry(BlockBuffer, FILE_CLUSTERS(FIRMWARE_FILE_SIZE_BYTES) + 1, 0xFFF);
+			break;
+
+		case 3: /* Block 3: Root file entries */
+			memcpy(BlockBuffer, &FirmwareFileEntry, sizeof(FATDirectoryEntry_t));
+			break;
+
+		default: /* Blocks 4 onwards: Data allocation section */
+			if ((BlockNumber >= 4) && (BlockNumber < (4 + FILE_SECTORS(FIRMWARE_FILE_SIZE_BYTES))))
+			{
+				uint32_t ReadFlashAddress = (uint32_t)(BlockNumber - 4) * SECTOR_SIZE_BYTES;
+
+				for (uint16_t i = 0; i < SECTOR_SIZE_BYTES; i++)
+				  BlockBuffer[i] = pgm_read_byte_far(ReadFlashAddress++);
+			}
+
+			break;
+	}
+
+	/* Write the entire read block Buffer to the host */
+	Endpoint_Write_Stream_LE(BlockBuffer, sizeof(BlockBuffer), NULL);
+	Endpoint_ClearIN();
+}
+
+/** Writes a number of blocks to the virtual FAT file system, from the host
+ *  PC via the USB Mass Storage interface.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to a structure containing a Mass Storage Class configuration and state
+ *  \param[in] BlockAddress  Data block starting address for the write sequence
+ *  \param[in] TotalBlocks   Number of blocks of data to write
+ */
+void VirtualFAT_WriteBlocks(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo,
+                            const uint32_t BlockAddress,
+                            uint16_t TotalBlocks)
+{
+	uint16_t CurrentBlock = (uint16_t)BlockAddress;
+
+	/* Emulated FAT is performed per-block, pass each requested block index
+	 * to the emulated FAT block write function */
+	while (TotalBlocks--)
+	  WriteVirtualBlock(CurrentBlock++);
+}
+
+/** Reads a number of blocks from the virtual FAT file system, and sends them
+ *  to the host PC via the USB Mass Storage interface.
+ *
+ *  \param[in] MSInterfaceInfo  Pointer to a structure containing a Mass Storage Class configuration and state
+ *  \param[in] BlockAddress  Data block starting address for the read sequence
+ *  \param[in] TotalBlocks   Number of blocks of data to read
+ */
+void VirtualFAT_ReadBlocks(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo,
+                           const uint32_t BlockAddress,
+                           uint16_t TotalBlocks)
+{
+	uint16_t CurrentBlock = (uint16_t)BlockAddress;
+
+	/* Emulated FAT is performed per-block, pass each requested block index
+	 * to the emulated FAT block read function */
+	while (TotalBlocks--)
+	  ReadVirtualBlock(CurrentBlock++);
+}
+
diff --git a/Bootloaders/MassStorage/Lib/VirtualFAT.h b/Bootloaders/MassStorage/Lib/VirtualFAT.h
new file mode 100644
index 000000000..af4548898
--- /dev/null
+++ b/Bootloaders/MassStorage/Lib/VirtualFAT.h
@@ -0,0 +1,159 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2013.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2013  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.
+*/
+
+#ifndef _VIRTUALFAT_H_
+#define _VIRTUALFAT_H_
+
+	/* Includes: */
+		#include <avr/io.h>
+		#include <avr/pgmspace.h>
+
+		#include <LUFA/Drivers/USB/USB.h>
+
+	/* Macros: */
+		/** Size of the virtual FIRMWARE.BIN file in bytes. */
+		#define FIRMWARE_FILE_SIZE_BYTES  (FLASHEND - (FLASHEND - BOOT_START_ADDR) + 1UL)
+
+		/** Number of sectors that comprise a single logical disk cluster. */
+		#define SECTOR_PER_CLUSTER        4
+
+		/** Size of a single logical sector on the disk. */
+		#define SECTOR_SIZE_BYTES         512
+
+		/** Size of a logical cluster on the disk, in bytes */
+		#define CLUSTER_SIZE_BYTES        (SECTOR_PER_CLUSTER * SECTOR_SIZE_BYTES)
+
+		/** Number of sectors required to store a given size in bytes.
+		 *
+		 *  \param[in] size  Size of the data that needs to be stored
+		 *
+		 *  \return Number of sectors required to store the given data on the disk.
+		 */
+		#define FILE_SECTORS(size)        ((size / SECTOR_SIZE_BYTES)  + ((size % SECTOR_SIZE_BYTES)  ? 1 : 0))
+
+		/** Number of clusters required to store a given size in bytes.
+		 *
+		 *  \param[in] size  Size of the data that needs to be stored
+		 *
+		 *  \return Number of clusters required to store the given data on the disk.
+		 */
+		#define FILE_CLUSTERS(size)       ((size / CLUSTER_SIZE_BYTES) + ((size % CLUSTER_SIZE_BYTES) ? 1 : 0))
+
+		/** Total number of logical sectors/blocks on the disk. */
+		#define LUN_MEDIA_BLOCKS          (FILE_SECTORS(FIRMWARE_FILE_SIZE_BYTES) + 32)
+
+		/** Converts a given time in HH:MM:SS format to a FAT filesystem time.
+		 *
+		 *  \note The minimum seconds resolution of FAT is 2, thus odd seconds
+		 *        will be truncated to the previous integer multiple of 2 seconds.
+		 *
+		 *  \param[in] hh  Hours (0-23)
+		 *  \param[in] mm  Minutes (0-59)
+		 *  \param[in] ss  Seconds (0-59)
+		 *
+		 *  \return Given time encoded as a FAT filesystem timestamp
+		 */
+		#define FAT_TIME(hh, mm, ss)      ((hh << 11) | (mm << 5) | (ss >> 1))
+
+		/** Converts a given date in DD/MM/YYYY format to a FAT filesystem date.
+		 *
+		 *  \param[in] dd    Days in the month (1-31)
+		 *  \param[in] mm    Months in the year (1-12)
+		 *  \param[in] yyyy  Year (1980 - 2107)
+		 *
+		 *  \return Given date encoded as a FAT filesystem datestamp
+		 */
+		#define FAT_DATE(dd, mm, yyyy)    (((yyyy - 1980) << 9) | (mm << 5) | (dd << 0))
+
+	/* Type Definitions: */
+		/** FAT boot block structure definition, used to identify the core
+		 *  parameters of a FAT filesystem stored on a disk.
+		 *
+		 *  \note This definition is truncated to save space; the magic signature
+		 *        0xAA55 must be appended to the very end of the block for it to
+		 *        be detected by the host as a valid boot block.
+		 */
+		typedef struct
+		{
+			uint8_t  Bootstrap[3];
+			uint8_t  Description[8];
+			uint16_t SectorSize;
+			uint8_t  SectorsPerCluster;
+			uint16_t ReservedSectors;
+			uint8_t  FATCopies;
+			uint16_t RootDirectoryEntries;
+			uint16_t TotalSectors16;
+			uint8_t  MediaDescriptor;
+			uint16_t SectorsPerFAT;
+			uint16_t SectorsPerTrack;
+			uint16_t Heads;
+			uint32_t HiddenSectors;
+			uint32_t TotalSectors32;
+			uint16_t PhysicalDriveNum;
+			uint8_t  ExtendedBootRecordSig;
+			uint32_t VolumeSerialNumber;
+			uint8_t  VolumeLabel[11];
+			uint8_t  FilesystemIdentifier[8];
+			/* uint8_t  BootstrapProgram[448]; */
+			/* uint16_t MagicSignature; */
+		} FATBootBlock_t;
+
+		/** FAT legacy 8.3 style directory entry structure definition, used to
+		 *  identify the files and folders of FAT filesystem stored on a disk.
+		 */
+		typedef struct
+		{
+			uint8_t  Filename[8];
+			uint8_t  Extension[3];
+			uint8_t  Attributes;
+			uint8_t  Reserved[10];
+			uint16_t CreationTime;
+			uint16_t CreationDate;
+			uint16_t StartingCluster;
+			uint32_t FileSizeBytes;
+		} FATDirectoryEntry_t;
+
+	/* Function Prototypes: */
+		#if defined(INCLUDE_FROM_VIRTUAL_FAT_C)
+			static void UpdateFAT12ClusterEntry(uint8_t* const FATTable,
+			                                    const uint16_t Index,
+			                                    const uint16_t ChainEntry);
+			static void WriteVirtualBlock(const uint16_t BlockNumber);
+			static void ReadVirtualBlock(const uint16_t BlockNumber);
+		#endif
+
+		void VirtualFAT_WriteBlocks(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo,
+		                            const uint32_t BlockAddress,
+		                            uint16_t TotalBlocks);
+
+		void VirtualFAT_ReadBlocks(USB_ClassInfo_MS_Device_t* const MSInterfaceInfo,
+		                           const uint32_t BlockAddress,
+		                           uint16_t TotalBlocks);
+#endif