Fixed incorrect buffer size check in the USBtoSerial project (thanks to Yuri A Nikifo...

[pub/USBasp.git] / Bootloaders / CDC / BootloaderCDC.c

diff --git a/Bootloaders/CDC/BootloaderCDC.c b/Bootloaders/CDC/BootloaderCDC.c
index 38f78da..7695e33 100644 (file)
--- a/Bootloaders/CDC/BootloaderCDC.c
+++ b/Bootloaders/CDC/BootloaderCDC.c
@@ -1,13 +1,13 @@
 /*
              LUFA Library
 /*
              LUFA Library

-     Copyright (C) Dean Camera, 2010.
+     Copyright (C) Dean Camera, 2011.

 
   dean [at] fourwalledcubicle [dot] com
 
   dean [at] fourwalledcubicle [dot] com

-      www.fourwalledcubicle.com
+           www.lufa-lib.org

 */
 
 /*
 */
 
 /*

-  Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+  Copyright 2011  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
 
   Permission to use, copy, modify, distribute, and sell this
   software and its documentation for any purpose is hereby granted


@@ -39,22 +39,22 @@
 /** 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.
  */
 /** 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.
  */

-CDC_Line_Coding_t LineEncoding = { .BaudRateBPS = 0,
-                                   .CharFormat  = OneStopBit,
-                                   .ParityType  = Parity_None,
-                                   .DataBits    = 8            };
+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.)
  */
 
 /** 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.)
  */

-uint32_t CurrAddress;
+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.
  */
 
 /** 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.
  */

-bool RunBootloader = true;
+static bool RunBootloader = true;

 
 
 /** Main program entry point. This routine configures the hardware required by the bootloader, then continuously
 
 
 /** Main program entry point. This routine configures the hardware required by the bootloader, then continuously


@@ -66,6 +66,9 @@ int main(void)
        /* Setup hardware required for the bootloader */
        SetupHardware();
 
        /* 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 */
        sei();
 
        /* Enable global interrupts so that the USB stack can function */
        sei();
 


@@ -100,6 +103,17 @@ void SetupHardware(void)
 
        /* Initialize USB Subsystem */
        USB_Init();
 
        /* Initialize USB Subsystem */
        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
 }
 
 /** Event handler for the USB_ConfigurationChanged event. This configures the device's endpoints ready


@@ -121,33 +135,43 @@ void EVENT_USB_Device_ConfigurationChanged(void)
                                   ENDPOINT_BANK_SINGLE);
 }
 
                                   ENDPOINT_BANK_SINGLE);
 }
 

-/** Event handler for the USB_UnhandledControlRequest event. This is used to catch standard and class specific
- *  control requests that are not handled internally by the USB library (including the CDC control commands,
- *  which are all issued via the control endpoint), so that they can be handled appropriately for the application.
+/** 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_UnhandledControlRequest(void)
+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)
        {
        /* Process CDC specific control requests */
        switch (USB_ControlRequest.bRequest)
        {

-               case REQ_GetLineEncoding:
+               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 */
                        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_Line_Coding_t));
+                               Endpoint_Write_Control_Stream_LE(&LineEncoding, sizeof(CDC_LineEncoding_t));

                                Endpoint_ClearOUT();
                        }
 
                        break;
                                Endpoint_ClearOUT();
                        }
 
                        break;

-               case REQ_SetLineEncoding:
+               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 */
                        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_Line_Coding_t));
+                               Endpoint_Read_Control_Stream_LE(&LineEncoding, sizeof(CDC_LineEncoding_t));

                                Endpoint_ClearIN();
                        }
 
                                Endpoint_ClearIN();
                        }
 


@@ -155,6 +179,7 @@ void EVENT_USB_Device_UnhandledControlRequest(void)
        }
 }
 
        }
 }
 

+#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 AVR910 protocol command issued.
  *
 /** Reads or writes a block of EEPROM or FLASH memory to or from the appropriate CDC data endpoint, depending
  *  on the AVR910 protocol command issued.
  *


@@ -236,15 +261,13 @@ static void ReadWriteMemoryBlock(const uint8_t Command)
 
                                        /* Increment the address counter after use */
                                        CurrAddress += 2;
 
                                        /* Increment the address counter after use */
                                        CurrAddress += 2;

-
-                                       HighByte = false;

                                }
                                else
                                {
                                        LowByte = FetchNextCommandByte();
                                }
                                else
                                {
                                        LowByte = FetchNextCommandByte();

-
-                                       HighByte = true;

                                }
                                }

+                               
+                               HighByte = !HighByte;

                        }
                        else
                        {
                        }
                        else
                        {


@@ -270,6 +293,7 @@ static void ReadWriteMemoryBlock(const uint8_t Command)
                WriteNextResponseByte('\r');
        }
 }
                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.
 
 /** 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.


@@ -294,7 +318,7 @@ static uint8_t FetchNextCommandByte(void)
        }
 
        /* Fetch the next byte from the OUT endpoint */
        }
 
        /* Fetch the next byte from the OUT endpoint */

-       return Endpoint_Read_Byte();
+       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
 }
 
 /** Writes the next response byte to the CDC data IN endpoint, and sends the endpoint back if needed to free up the


@@ -319,8 +343,8 @@ static void WriteNextResponseByte(const uint8_t Response)
                }
        }
 
                }
        }
 

-       /* Write the next byte to the OUT endpoint */
-       Endpoint_Write_Byte(Response);
+       /* Write the next byte to the IN endpoint */
+       Endpoint_Write_8(Response);

 }
 
 /** Task to read in AVR910 commands from the CDC data OUT endpoint, process them, perform the required actions
 }
 
 /** Task to read in AVR910 commands from the CDC data OUT endpoint, process them, perform the required actions


@@ -332,219 +356,230 @@ void CDC_Task(void)
        Endpoint_SelectEndpoint(CDC_RX_EPNUM);
 
        /* Check if endpoint has a command in it sent from the host */
        Endpoint_SelectEndpoint(CDC_RX_EPNUM);
 
        /* Check if endpoint has a command in it sent from the host */

-       if (Endpoint_IsOUTReceived())
-       {
-               /* Read in the bootloader command (first byte sent from host) */
-               uint8_t Command = FetchNextCommandByte();
+       if (!(Endpoint_IsOUTReceived()))
+         return;

 
 

-               if ((Command == 'L') || (Command == 'P') || (Command == 'T') || (Command == 'E'))
-               {
-                       if (Command == 'E')
-                         RunBootloader = false;
-                       else if (Command == 'T')
-                         FetchNextCommandByte();
+       /* Read in the bootloader command (first byte sent from host) */
+       uint8_t Command = FetchNextCommandByte();

 
 

-                       /* Send confirmation byte back to the host */
-                       WriteNextResponseByte('\r');
-               }
-               else if (Command == 't')
-               {
-                       /* Return ATMEGA128 part code - this is only to allow AVRProg to use the bootloader */
-                       WriteNextResponseByte(0x44);
-                       WriteNextResponseByte(0x00);
-               }
-               else if (Command == 'a')
-               {
-                       /* Indicate auto-address increment is supported */
-                       WriteNextResponseByte('Y');
-               }
-               else if (Command == 'A')
-               {
-                       /* Set the current address to that given by the host */
-                       CurrAddress   = (FetchNextCommandByte() << 9);
-                       CurrAddress  |= (FetchNextCommandByte() << 1);
+       if (Command == 'E')
+       {
+               RunBootloader = false;
+       
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if (Command == 'T')
+       {
+               FetchNextCommandByte();

 
 

-                       /* Send confirmation byte back to the host */
-                       WriteNextResponseByte('\r');
-               }
-               else if (Command == 'p')
-               {
-                       /* Indicate serial programmer back to the host */
-                       WriteNextResponseByte('S');
-               }
-               else if (Command == 'S')
-               {
-                       /* Write the 7-byte software identifier to the endpoint */
-                       for (uint8_t CurrByte = 0; CurrByte < 7; CurrByte++)
-                         WriteNextResponseByte(SOFTWARE_IDENTIFIER[CurrByte]);
-               }
-               else if (Command == 'V')
-               {
-                       WriteNextResponseByte('0' + BOOTLOADER_VERSION_MAJOR);
-                       WriteNextResponseByte('0' + BOOTLOADER_VERSION_MINOR);
-               }
-               else if (Command == 's')
-               {
-                       WriteNextResponseByte(AVR_SIGNATURE_3);
-                       WriteNextResponseByte(AVR_SIGNATURE_2);
-                       WriteNextResponseByte(AVR_SIGNATURE_1);
-               }
-               else if (Command == 'b')
-               {
-                       WriteNextResponseByte('Y');
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if ((Command == 'L') || (Command == 'P'))
+       {
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if (Command == 't')
+       {
+               /* Return ATMEGA128 part code - this is only to allow AVRProg to use the bootloader */
+               WriteNextResponseByte(0x44);
+               WriteNextResponseByte(0x00);
+       }
+       else if (Command == 'a')
+       {
+               /* Indicate auto-address increment is supported */
+               WriteNextResponseByte('Y');
+       }
+       else if (Command == 'A')
+       {
+               /* Set the current address to that given by the host */
+               CurrAddress   = (FetchNextCommandByte() << 9);
+               CurrAddress  |= (FetchNextCommandByte() << 1);

 
 

-                       /* Send block size to the host */
-                       WriteNextResponseByte(SPM_PAGESIZE >> 8);
-                       WriteNextResponseByte(SPM_PAGESIZE & 0xFF);
-               }
-               else if (Command == 'e')
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if (Command == 'p')
+       {
+               /* Indicate serial programmer back to the host */
+               WriteNextResponseByte('S');
+       }
+       else if (Command == 'S')
+       {
+               /* Write the 7-byte software identifier to the endpoint */
+               for (uint8_t CurrByte = 0; CurrByte < 7; CurrByte++)
+                 WriteNextResponseByte(SOFTWARE_IDENTIFIER[CurrByte]);
+       }
+       else if (Command == 'V')
+       {
+               WriteNextResponseByte('0' + BOOTLOADER_VERSION_MAJOR);
+               WriteNextResponseByte('0' + BOOTLOADER_VERSION_MINOR);
+       }
+       else if (Command == 's')
+       {
+               WriteNextResponseByte(AVR_SIGNATURE_3);
+               WriteNextResponseByte(AVR_SIGNATURE_2);
+               WriteNextResponseByte(AVR_SIGNATURE_1);
+       }
+       else if (Command == 'e')
+       {
+               /* Clear the application section of flash */
+               for (uint32_t CurrFlashAddress = 0; CurrFlashAddress < BOOT_START_ADDR; CurrFlashAddress += SPM_PAGESIZE)

                {
                {

-                       /* Clear the application section of flash */
-                       for (uint32_t CurrFlashAddress = 0; CurrFlashAddress < BOOT_START_ADDR; CurrFlashAddress++)
-                       {
-                               boot_page_erase(CurrFlashAddress);
-                               boot_spm_busy_wait();
-                               boot_page_write(CurrFlashAddress);
-                               boot_spm_busy_wait();
-
-                               CurrFlashAddress += SPM_PAGESIZE;
-                       }
-
-                       /* Send confirmation byte back to the host */
-                       WriteNextResponseByte('\r');
+                       boot_page_erase(CurrFlashAddress);
+                       boot_spm_busy_wait();
+                       boot_page_write(CurrFlashAddress);
+                       boot_spm_busy_wait();

                }
                }

-               else if (Command == 'l')
-               {
-                       /* Set the lock bits to those given by the host */
-                       boot_lock_bits_set(FetchNextCommandByte());

 
 

-                       /* Send confirmation byte back to the host */
-                       WriteNextResponseByte('\r');
-               }
-               else if (Command == 'r')
-               {
-                       WriteNextResponseByte(boot_lock_fuse_bits_get(GET_LOCK_BITS));
-               }
-               else if (Command == 'F')
-               {
-                       WriteNextResponseByte(boot_lock_fuse_bits_get(GET_LOW_FUSE_BITS));
-               }
-               else if (Command == 'N')
-               {
-                       WriteNextResponseByte(boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS));
-               }
-               else if (Command == 'Q')
-               {
-                       WriteNextResponseByte(boot_lock_fuse_bits_get(GET_EXTENDED_FUSE_BITS));
-               }
-               else if (Command == 'C')
-               {
-                       /* Write the high byte to the current flash page */
-                       boot_page_fill(CurrAddress, FetchNextCommandByte());
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       #if !defined(NO_LOCK_BYTE_WRITE_SUPPORT)
+       else if (Command == 'l')
+       {
+               /* Set the lock bits to those given by the host */
+               boot_lock_bits_set(FetchNextCommandByte());

 
 

-                       /* Send confirmation byte back to the host */
-                       WriteNextResponseByte('\r');
-               }
-               else if (Command == 'c')
-               {
-                       /* Write the low byte to the current flash page */
-                       boot_page_fill(CurrAddress | 1, FetchNextCommandByte());
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       #endif
+       else if (Command == 'r')
+       {
+               WriteNextResponseByte(boot_lock_fuse_bits_get(GET_LOCK_BITS));
+       }
+       else if (Command == 'F')
+       {
+               WriteNextResponseByte(boot_lock_fuse_bits_get(GET_LOW_FUSE_BITS));
+       }
+       else if (Command == 'N')
+       {
+               WriteNextResponseByte(boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS));
+       }
+       else if (Command == 'Q')
+       {
+               WriteNextResponseByte(boot_lock_fuse_bits_get(GET_EXTENDED_FUSE_BITS));
+       }
+       #if !defined(NO_BLOCK_SUPPORT)
+       else if (Command == 'b')
+       {
+               WriteNextResponseByte('Y');

 
 

-                       /* Increment the address */
-                       CurrAddress += 2;
+               /* Send block size to the host */
+               WriteNextResponseByte(SPM_PAGESIZE >> 8);
+               WriteNextResponseByte(SPM_PAGESIZE & 0xFF);
+       }
+       else if ((Command == 'B') || (Command == 'g'))
+       {
+               /* Delegate the block write/read to a separate function for clarity */
+               ReadWriteMemoryBlock(Command);
+       }
+       #endif
+       #if !defined(NO_FLASH_BYTE_SUPPORT)
+       else if (Command == 'C')
+       {
+               /* 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 == 'm')
-               {
-                       /* Commit the flash page to memory */
-                       boot_page_write(CurrAddress);
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if (Command == 'c')
+       {
+               /* Write the low byte to the current flash page */
+               boot_page_fill(CurrAddress | 0x01, FetchNextCommandByte());

 
 

-                       /* Wait until write operation has completed */
-                       boot_spm_busy_wait();
+               /* Increment the address */
+               CurrAddress += 2;

 
 

-                       /* Send confirmation byte back to the host */
-                       WriteNextResponseByte('\r');
-               }
-               else if ((Command == 'B') || (Command == 'g'))
-               {
-                       /* Delegate the block write/read to a separate function for clarity */
-                       ReadWriteMemoryBlock(Command);
-               }
-               else if (Command == 'R')
-               {
-                       #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);
-               }
-               else if (Command == 'D')
-               {
-                       /* Read the byte from the endpoint and write it to the EEPROM */
-                       eeprom_write_byte((uint8_t*)((intptr_t)(CurrAddress >> 1)), FetchNextCommandByte());
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if (Command == 'm')
+       {
+               /* Commit the flash page to memory */
+               boot_page_write(CurrAddress);

 
 

-                       /* Increment the address after use */
-                       CurrAddress += 2;
+               /* Wait until write operation has completed */
+               boot_spm_busy_wait();

 
 

-                       /* Send confirmation byte back to the host */
-                       WriteNextResponseByte('\r');
-               }
-               else if (Command == 'd')
-               {
-                       /* Read the EEPROM byte and write it to the endpoint */
-                       WriteNextResponseByte(eeprom_read_byte((uint8_t*)((intptr_t)(CurrAddress >> 1))));
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if (Command == 'R')
+       {
+               #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 == 'D')
+       {
+               /* Read the byte from the endpoint and write it to the EEPROM */
+               eeprom_write_byte((uint8_t*)((intptr_t)(CurrAddress >> 1)), FetchNextCommandByte());

 
 

-                       /* Increment the address after use */
-                       CurrAddress += 2;
-               }
-               else if (Command == 27)
-               {
-                       /* Escape is sync, ignore */
-               }
-               else
-               {
-                       /* Unknown command, return fail code */
-                       WriteNextResponseByte('?');
-               }
+               /* Increment the address after use */
+               CurrAddress += 2;

 
 

-               /* Select the IN endpoint */
-               Endpoint_SelectEndpoint(CDC_TX_EPNUM);
+               /* Send confirmation byte back to the host */
+               WriteNextResponseByte('\r');
+       }
+       else if (Command == 'd')
+       {
+               /* Read the EEPROM byte and write it to the endpoint */
+               WriteNextResponseByte(eeprom_read_byte((uint8_t*)((intptr_t)(CurrAddress >> 1))));

 
 

-               /* Remember if the endpoint is completely full before clearing it */
-               bool IsEndpointFull = !(Endpoint_IsReadWriteAllowed());
+               /* Increment the address after use */
+               CurrAddress += 2;
+       }
+       #endif
+       else if (Command != 27)
+       {
+               /* Unknown (non-sync) command, return fail code */
+               WriteNextResponseByte('?');
+       }

 
 

-               /* Send the endpoint data to the host */
-               Endpoint_ClearIN();
+       /* Select the IN endpoint */
+       Endpoint_SelectEndpoint(CDC_TX_EPNUM);

 
 

-               /* 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;
-                       }
+       /* Remember if the endpoint is completely full before clearing it */
+       bool IsEndpointFull = !(Endpoint_IsReadWriteAllowed());

 
 

-                       Endpoint_ClearIN();
-               }
+       /* Send the endpoint data to the host */
+       Endpoint_ClearIN();

 
 

-               /* Wait until the data has been sent to the host */
+       /* 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;
                }
 
                while (!(Endpoint_IsINReady()))
                {
                        if (USB_DeviceState == DEVICE_STATE_Unattached)
                          return;
                }
 

-               /* Select the OUT endpoint */
-               Endpoint_SelectEndpoint(CDC_RX_EPNUM);
+               Endpoint_ClearIN();
+       }

 
 

-               /* Acknowledge the command from the host */
-               Endpoint_ClearOUT();
+       /* 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_EPNUM);
+
+       /* Acknowledge the command from the host */
+       Endpoint_ClearOUT();

 }
 
 }