Fixed USB_GetHIDReportItemInfo() function modifying the given report item's data when the report item does not exist within the supplied report of a multiple report HID device.

LUFA/Drivers/USB/Class/Host/HIDParser.c

@@ -276,7 +276,7 @@ uint8_t USB_ProcessHIDReport(const uint8_t* ReportData,
 		{
 			UsageMinMax.Minimum = 0;
 			UsageMinMax.Maximum = 0;
-			UsageListSize   = 0;
+			UsageListSize       = 0;
 		}
 	}
 	
@@ -292,9 +292,6 @@ bool USB_GetHIDReportItemInfo(const uint8_t* ReportData,
 	uint16_t DataBitsRem  = ReportItem->Attributes.BitSize;
 	uint16_t CurrentBit   = ReportItem->BitOffset;
 	uint32_t BitMask      = (1 << 0);
-
-	ReportItem->PreviousValue = ReportItem->Value;
-	ReportItem->Value = 0;
 	
 	if (ReportItem->ReportID)
 	{
@@ -304,6 +301,9 @@ bool USB_GetHIDReportItemInfo(const uint8_t* ReportData,
 		ReportData++;
 	}
 
+	ReportItem->PreviousValue = ReportItem->Value;
+	ReportItem->Value = 0;
+
 	while (DataBitsRem--)
 	{
 		if (ReportData[CurrentBit / 8] & (1 << (CurrentBit % 8)))

LUFA/Drivers/USB/Class/Host/HIDParser.h

@@ -285,8 +285,10 @@
 			/** Extracts the given report item's value out of the given HID report and places it into the Value
 			 *  member of the report item's \ref HID_ReportItem_t structure.
 			 *
-			 *  When called, this copies the report item's Value element to it's PreviousValue element for easy
+			 *  When called on a report with an item that exists in that report, this copies the report item's Value 
-			 *  checking to see if an item's value has changed before processing a report.
+			 *  to it's PreviousValue element for easy checking to see if an item's value has changed before processing
+			 *  a report. If the given item does not exist in the report, the function does not modify the report item's
+			 *  data.
 			 *
 			 *  \param[in]     ReportData  Buffer containing an IN or FEATURE report from an attached device.
 			 *  \param[in,out] ReportItem  Pointer to the report item of interest in a \ref HID_ReportInfo_t ReportItem array.

LUFA/ManPages/ChangeLog.txt

@@ -13,6 +13,10 @@
   *    with basic code
   *  - Changed over all device demos to use a clearer algorithm for the configuring of the application's endpoints
   *
+  *  <b>Fixed:</b>
+  *  - Fixed USB_GetHIDReportItemInfo() function modifying the given report item's data when the report item does not exist
+  *    within the supplied report of a multiple report HID device
+  *
   *  \section Sec_ChangeLog100807 Version 100807
   *  <b>New:</b>
   *  - Added new ADC_DisableChannel() function (thanks to Mich Davis)