iokit/Families/IOHIDSystem/IOHIDDescriptorParser/HIDUsageAndPageFromIndex.c

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23         File:           HIDUsageAndPageFromIndex.c
  24
  25         Contains:       xxx put contents here xxx
  26
  27         Version:        xxx put version here xxx
  28
  29         Copyright:      © 1999-2000 by Apple Computer, Inc., all rights reserved.
  30
  31         File Ownership:
  32
  33                 DRI:                            xxx put dri here xxx
  34
  35                 Other Contact:          xxx put other contact here xxx
  36
  37                 Technology:                     xxx put technology here xxx
  38
  39         Writers:
  40
  41                 (KH)    Keithen Hayenga
  42                 (BWS)   Brent Schorsch
  43
  44         Change History (most recent first):
  45
  46           <USB2>        12/12/00        KH              range count off by 1.
  47           <USB1>          3/5/99        BWS             first checked in
  48 */
  49
  50 #include "HIDLib.h"
  51
  52 /*
  53  *------------------------------------------------------------------------------
  54  *
  55  * HIDUsageAndPageFromIndex
  56  *
  57  *       Input:
  58  *                        ptPreparsedData               - The Preparsed Data
  59  *                        ptReportItem                  - The Report Item
  60  *                        index                            - The usage Index
  61  *                        ptUsageAndPage                - The usage And Page
  62  *       Output:
  63  *       Returns:
  64  *
  65  *------------------------------------------------------------------------------
  66 */
  67 void HIDUsageAndPageFromIndex (HIDPreparsedDataRef preparsedDataRef,
  68                                                                  HIDReportItem *ptReportItem, UInt32 index,
  69                                                                  HIDUsageAndPage *ptUsageAndPage)
  70 {
  71         HIDPreparsedDataPtr ptPreparsedData = (HIDPreparsedDataPtr) preparsedDataRef;
  72         HIDP_UsageItem *ptUsageItem = NULL;
  73         int iUsageItem;
  74         int iUsages;
  75         int i;
  76
  77 /*
  78  *      Disallow NULL Pointers
  79 */
  80         if ((ptUsageAndPage == NULL) || (ptReportItem == NULL) || (ptPreparsedData == NULL))
  81         {
  82                 ptUsageAndPage->usagePage = 0;
  83                 return; // kHIDNullPointerErr;
  84         }
  85
  86 /*
  87  *      Index through the usage Items for this ReportItem
  88 */
  89         iUsageItem = ptReportItem->firstUsageItem;
  90         for (i=0; i<ptReportItem->usageItemCount; i++)
  91         {
  92 /*
  93  *              Each usage Item is either a usage or a usage range
  94 */
  95                 ptUsageItem = &ptPreparsedData->usageItems[iUsageItem++];
  96                 if (ptUsageItem->isRange)
  97                 {
  98 /*
  99  *                      For usage Ranges
 100  *                        If the index is in the range
 101  *                              then return the usage
 102  *                        Otherwise adjust the index by the size of the range
 103 */
 104                         iUsages = ptUsageItem->usageMaximum - ptUsageItem->usageMinimum;
 105                         if (iUsages < 0)
 106                                 iUsages = -iUsages;
 107                         iUsages++;              // Add off by one adjustment AFTER sign correction.
 108                         if (iUsages > index)
 109                         {
 110                                 ptUsageAndPage->usagePage = ptUsageItem->usagePage;
 111                                 ptUsageAndPage->usage = ptUsageItem->usageMinimum + index;
 112                                 return;
 113                         }
 114                         index -= iUsages;
 115                 }
 116                 else
 117                 {
 118 /*
 119  *                      For Usages
 120  *                      If the index is zero
 121  *                        then return this usage
 122  *                      Otherwise one less to index through
 123 */
 124                         if (index-- == 0)
 125                         {
 126                                 ptUsageAndPage->usagePage = ptUsageItem->usagePage;
 127                                 ptUsageAndPage->usage = ptUsageItem->usage;
 128                                 return;
 129                         }
 130                 }
 131         }
 132         if (ptUsageItem != NULL)
 133         {
 134                 ptUsageAndPage->usagePage = ptUsageItem->usagePage;
 135                 if (ptUsageItem->isRange)
 136                         ptUsageAndPage->usage = ptUsageItem->usageMaximum;
 137                 else
 138                         ptUsageAndPage->usage = ptUsageItem->usage;
 139         }
 140 }