HIDGetNextUsageValueInfo.c   [plain text]

/*
 *
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 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
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 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
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 * file.
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/*
	File:		HIDGetNextUsageValueInfo.c

	Contains:	HIDGetNextUsageValueInfo call for HID Library

	Version:	1.0d1

	Copyright:	© 2000 by Apple Computer, Inc., all rights reserved.

	File Ownership:

		DRI:				David Ferguson

		Other Contact:		Keithen Hayenga

		Technology:			technologies, usb

	Writers:

		(KH)	Keithen Hayenga

	Change History (most recent first):

	  <USB1>	 2/14/00	KH		first checked in
*/

#include "HIDLib.h"

/*
 *------------------------------------------------------------------------------
 *
 * HIDGetNextUsageValueInfo - Get report id and collection for a usage. In keeping
 *								with USBGetNextInterface, we find the usage in the
 *								next collection, so that you can find usages that
 *								have the same usage and usage page.
 *
 *	 Input:
 *			  reportType			- HIDP_Input, HIDP_Output, HIDP_Feature
 *			  usagePage				- Page Criteria or zero
 *			  usage					- The usage to get the information for
 *			  collection			- Starting Collection Criteria or zero
 *			  preparsedDataRef		- Pre-Parsed Data
 *	 Output:
 *			  collection			- Final Collection Criteria or no change
 *			  reportID				- Report ID or no change
 *	 Returns:
 *			  kHIDBadParameterErr when there are no more collections to search.
 *
 *------------------------------------------------------------------------------
*/
OSStatus HIDGetNextUsageValueInfo
		   (HIDReportType			reportType,
			HIDUsage				usagePage,
			HIDUsage				usage,
			UInt32 *				collection,
			UInt8 *					reportID,
			HIDPreparsedDataRef		preparsedDataRef)
{
	HIDPreparsedDataPtr ptPreparsedData = (HIDPreparsedDataPtr)preparsedDataRef;
	HIDReportItem *ptReportItem;
	UInt32 iCollection;
	UInt32 newCollection = 0xFFFFFFFF;
	int iR;
	UInt8 newReportID = 0;
	OSStatus iStatus = kHIDUsageNotFoundErr;

	//Disallow Null Pointers

	if ((ptPreparsedData == NULL) || (collection == NULL) || (reportID == NULL))
		return kHIDNullPointerErr;
	if (ptPreparsedData->hidTypeIfValid != kHIDOSType)
		return kHIDInvalidPreparsedDataErr;

	// The Collection must be in range

	iCollection = *collection;
	// Umm... an unsigned number can never be less than 0!
	if ((iCollection < 0) || (iCollection >= ptPreparsedData->collectionCount))
		return kHIDBadParameterErr;

	// HIDGetNextUsageValueInfo is different from HIDGetUsageValue in how it treats
	// the collection parameter. HIDGetUsageValue will only look at report items that
	// are within the collection and can therefore limit it's searches to starting at
	// ptPreparsedData->collections[iCollection]->firstReportItem and only check
	// ptPreparsedData->collections[iCollection]->reportItemCount. Since we want to 
	// find the NEXT collection as well, we need to cycle through all of the reports.

	for (iR = 0; iR < ptPreparsedData->reportItemCount; iR++)
	{
		SInt32 minUsage;
		SInt32 maxUsage;
		HIDP_UsageItem thisUsage;

		ptReportItem = &ptPreparsedData->reportItems[iR];
		
		thisUsage = ptPreparsedData->usageItems[ptReportItem->firstUsageItem];

		if (thisUsage.isRange)
		{
			minUsage = thisUsage.usageMinimum;
			maxUsage = thisUsage.usageMaximum;
		}
		else
		{
			minUsage = thisUsage.usage;
			maxUsage = thisUsage.usage;
		}
		
		if (ptReportItem->reportType == reportType &&
			(usagePage == 0 || ptReportItem->globals.usagePage == usagePage) &&
			(usage >= minUsage && usage <= maxUsage) &&
			ptReportItem->parent > iCollection &&
			HIDIsVariable(ptReportItem, preparsedDataRef))
		{
			if (ptReportItem->parent < newCollection)
			{
				newCollection = ptReportItem->parent;
				newReportID = iR;
				iStatus = noErr;
			}
		}
	}
		
	if (iStatus == noErr)
	{
		*reportID = newReportID;
		*collection = newCollection;
	}

	return iStatus;
}