iokit/Families/IOHIDSystem/IOHIDDescriptorParser/HIDGetReportLength.c

   1 /*
   2  * Copyright (c) 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:           HIDGetReportLength.c
  24
  25         Contains:       xxx put contents here xxx
  26
  27         Version:        xxx put version here xxx
  28
  29         Copyright:      © 2000 by Apple Computer, Inc., all rights reserved.
  30
  31         File Ownership:
  32
  33                 DRI:                            David Ferguson
  34
  35                 Other Contact:          Keithen Hayenga
  36
  37                 Technology:                     technologies, usb
  38
  39         Writers:
  40
  41
  42         Change History (most recent first):
  43
  44 */
  45
  46 #include "HIDLib.h"
  47
  48 /*
  49  *------------------------------------------------------------------------------
  50  *
  51  * HIDGetReportLength - Get the length of a report
  52  *
  53  *       Input:
  54  *                              reportType                      - HIDP_Input, HIDP_Output, HIDP_Feature
  55  *                              reportID                        - Desired Report
  56  *                              preparsedDataRef        - opaque Pre-Parsed Data
  57  *       Output:
  58  *                              reportLength            - The length of the Report
  59  *       Returns:
  60  *                              status                          kHIDNullPointerErr, kHIDInvalidPreparsedDataErr,
  61  *                                                                      kHIDUsageNotFoundErr
  62  *
  63  *------------------------------------------------------------------------------
  64 */
  65 OSStatus HIDGetReportLength(HIDReportType reportType,
  66                                                         UInt8 reportID,
  67                                                         ByteCount * reportLength,
  68                                                         HIDPreparsedDataRef preparsedDataRef)
  69 {
  70         HIDPreparsedDataPtr ptPreparsedData = (HIDPreparsedDataPtr)preparsedDataRef;
  71         ByteCount dataLength = 0;
  72         OSStatus iStatus = kHIDUsageNotFoundErr;
  73         int iR;
  74
  75         // Disallow Null Pointers.
  76
  77         if (ptPreparsedData == NULL || reportLength == NULL)
  78                 return kHIDNullPointerErr;
  79         if (ptPreparsedData->hidTypeIfValid != kHIDOSType)
  80                 return kHIDInvalidPreparsedDataErr;
  81
  82         // Go through the Reports.
  83
  84         for (iR = 0; iR < ptPreparsedData->reportCount; iR++)
  85         {
  86                 if (ptPreparsedData->reports[iR].reportID == reportID)
  87                 {
  88                         switch(reportType)
  89                         {
  90                                 case kHIDInputReport:
  91                                         dataLength = (ptPreparsedData->reports[iR].inputBitCount + 7)/8;
  92                                         break;
  93                                 case kHIDOutputReport:
  94                                         dataLength = (ptPreparsedData->reports[iR].outputBitCount + 7)/8;
  95                                         break;
  96                                 case kHIDFeatureReport:
  97                                         dataLength = (ptPreparsedData->reports[iR].featureBitCount + 7)/8;
  98                                         break;
  99                                 default:
 100                                         return kHIDInvalidReportTypeErr;
 101                         }
 102                         break;
 103                 }
 104         }
 105
 106         // If the reportID > 0, there must be 1 byte for reportID, so total report must be > 1.
 107         // (Would come into play if we had input report 3, but searched for ouput report 3
 108         // that didn't exist.)
 109
 110         if ((reportID == 0) && (dataLength > 0) || dataLength > 1)
 111         {
 112                 iStatus = noErr;
 113         }
 114         else
 115         {
 116                 dataLength = 0;         // Ignore report that had id, but no data.
 117         }
 118
 119         *reportLength = dataLength;
 120
 121         return iStatus;
 122 }