Changed MIDI event structure MIDI_EventPacket_t to use a single field for the combined virtual cable index and command ID, to prevent bitfield packing issues on some architectures (thanks to Darren Gibbs).

3 files changed, 21 insertions, 2 deletions

diff --git a/LUFA/DoxygenPages/ChangeLog.txt b/LUFA/DoxygenPages/ChangeLog.txt
index 150d5de39..df504763c 100644
--- a/LUFA/DoxygenPages/ChangeLog.txt
+++ b/LUFA/DoxygenPages/ChangeLog.txt
@@ -33,6 +33,8 @@
   *   - The Pipe_ConfigurePipe() function no longer takes a number of banks as a special mask; the number of banks is now specified as an integer parameter
   *   - Pipes are now configured via instances of a new struct USB_Pipe_Table_t in all host mode class drivers, rather than a list of pipe parameters
   *   - Added support for various assert and debugging macros for the UC3 devices
+  *   - Changed MIDI event structure MIDI_EventPacket_t to use a single field for the combined virtual cable index and command ID, to prevent bitfield packing issues
+  *     on some architectures (thanks to Darren Gibbs).
   *  - Library Applications:
   *   - Raised the guard bits in the AVRISP-MKII clone project when in PDI and TPI to 32, to prevent communication errors on low quality connections to a target
   *   - Added additional bootloader API data to expose the bootloader start address and class to the DFU and CDC class bootloaders
diff --git a/LUFA/DoxygenPages/MigrationInformation.txt b/LUFA/DoxygenPages/MigrationInformation.txt
index fe0473284..f0fd9b210 100644
--- a/LUFA/DoxygenPages/MigrationInformation.txt
+++ b/LUFA/DoxygenPages/MigrationInformation.txt
@@ -27,6 +27,9 @@
  *      to update their class driver struct instantiation to match the new scheme (see \ref USB_Endpoint_Table_t).
  *    - The \c ENDPOINT_BANKS_SUPPORTED() and \c ENDPOINT_MAX_ENDPOINT_SIZE() macros have been removed, as these do not function correctly with the new addressing
  *      scheme for the endpoint APIs. Please refer to the target device's datasheet for the maximum bank size of each endpoint.
+ *    - The MIDI class driver \ref MIDI_EventPacket_t event packet no longer contains seperate \c CableIndex and \c Command entries; these have been combined
+ *      into a single \c Event element which can be contructed using the new macro \ref MIDI_EVENT(). Existing applications should use the new macro and structure
+ *      element name.
  *
  *  <b>Host Mode</b>
  *    - The Android Accessory Host class driver property strings are now a array of \c char* rather than a struct of named pointers. Existing applications
@@ -38,6 +41,9 @@
  *      calls to use full pipe addresses when required within the device.
  *    - All host mode class drivers have been updated to use a new unified pipe description structure for all pipes; existing applications will need to update
  *      their class driver struct instantiation to match the new scheme (see \ref USB_Pipe_Table_t).
+ *    - The MIDI class driver \ref MIDI_EventPacket_t event packet no longer contains seperate \c CableIndex and \c Command entries; these have been combined
+ *      into a single \c Event element which can be contructed using the new macro \ref MIDI_EVENT(). Existing applications should use the new macro and structure
+ *      element name.
  *
  *  \section Sec_Migration120219 Migrating from 111009 to 120219
  *  <b>USB Core</b>
diff --git a/LUFA/Drivers/USB/Class/Common/MIDIClassCommon.h b/LUFA/Drivers/USB/Class/Common/MIDIClassCommon.h
index 60b0908f3..25b80b7d4 100644
--- a/LUFA/Drivers/USB/Class/Common/MIDIClassCommon.h
+++ b/LUFA/Drivers/USB/Class/Common/MIDIClassCommon.h
@@ -84,8 +84,20 @@
 		 *  addresses are zero-indexed. This converts a natural MIDI channel number into the logical channel address.
 		 *
 		 *  \param[in] channel  MIDI channel number to address.
+		 *
+		 *  \return Constructed MIDI channel ID.
 		 */
 		#define MIDI_CHANNEL(channel)        ((channel) - 1)
+		
+		/** Constructs a MIDI event ID from a given MIDI command and a virtual MIDI cable index. This can then be
+		 *  used to create and decode \ref MIDI_EventPacket_t MIDI event packets.
+		 *
+		 *  \param[in] virtualcable  Index of the virtual MIDI cable the event relates to
+		 *  \param[in] command       MIDI command to send through the virtual MIDI cable
+		 *
+		 *  \return Constructed MIDI event ID.
+		 */
+		#define MIDI_EVENT(virtualcable, command) ((virtualcable << 4) | (command >> 4))
 
 	/* Enums: */
 		/** Enum for the possible MIDI jack types in a MIDI device jack descriptor. */
@@ -290,8 +302,7 @@
 		 */
 		typedef struct
 		{
-			unsigned Command     : 4; /**< Upper nibble of the MIDI command being sent or received in the event packet. */
-			unsigned CableNumber : 4; /**< Virtual cable number of the event being sent or received in the given MIDI interface. */
+			uint8_t Event; /**< MIDI event type, constructed with the \ref MIDI_EVENT() macro. */
 
 			uint8_t  Data1; /**< First byte of data in the MIDI event. */
 			uint8_t  Data2; /**< Second byte of data in the MIDI event. */