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1 // Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies). |
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2 // All rights reserved. |
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3 // This component and the accompanying materials are made available |
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4 // under the terms of the License "Eclipse Public License v1.0" |
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5 // which accompanies this distribution, and is available |
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6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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7 // |
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8 // Initial Contributors: |
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9 // Nokia Corporation - initial contribution. |
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10 // |
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11 // Description: |
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12 // Symbian USBDI Descriptor Parsing Framework. |
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13 // |
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14 // |
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15 |
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16 /** |
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17 @file |
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18 @internalComponent |
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19 */ |
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20 |
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21 #include <d32usbdescriptors.h> |
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22 #include "usbdescutils.h" |
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23 |
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24 |
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25 // --------------------- |
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26 // UsbDescriptorParser |
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27 // --------------------- |
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28 |
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29 /** |
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30 The main parsing function of the USB descriptor parsing framework. |
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31 |
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32 This will perform a best effort parse of a USB descriptor tree. It is best effort in the |
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33 fact that upon encountering a form of syntatic corruption in the source data it will error |
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34 the parse attempt, but also return the incomplete descriptor tree up to the parsing error. |
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35 |
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36 @param aUsbDes The source data that will be parsed. |
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37 @param aDesc The pointer that will be updated to the top-level descriptor. |
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38 |
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39 @return KErrNone if successful, a system-wide error code otherwise. |
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40 |
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41 @publishedPartner |
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42 @prototype |
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43 */ |
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44 EXPORT_C /*static*/ TInt UsbDescriptorParser::Parse(const TDesC8& aUsbDes, TUsbGenericDescriptor*& aDesc) |
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45 { |
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46 TInt ret = KErrNone; |
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47 aDesc = NULL; |
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48 TPtrC8 des(aUsbDes); |
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49 |
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50 // First we must find the top level descriptor (the one we will return to the caller). |
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51 TRAP(ret, aDesc = FindParserAndParseAndCheckL(des, NULL)); |
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52 if(ret == KErrNone) |
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53 { |
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54 if(!aDesc) |
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55 { |
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56 ret = KErrNotFound; |
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57 } |
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58 else |
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59 { |
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60 // Now we have a top level descriptor - we now try to build up the descriptor |
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61 // tree if there are more descriptors available. |
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62 TRAP(ret, ParseDescriptorTreeL(des, *aDesc)); |
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63 } |
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64 } |
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65 |
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66 // Ensure that all the data has been parsed if successful. |
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67 if(ret == KErrNone && des.Length() > 0) |
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68 { |
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69 // If no parser was found for some data then we should have been errored with KErrNotFound. |
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70 __ASSERT_DEBUG(EFalse, UsbDescFault(UsbdiFaults::EUsbDescSuccessButDataLeftUnparsed)); |
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71 ret = KErrUnknown; |
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72 } |
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73 |
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74 // release the allocated descriptor if there was an error |
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75 if(ret != KErrNone && aDesc) |
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76 { |
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77 delete aDesc; |
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78 aDesc = NULL; |
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79 } |
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80 |
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81 return ret; |
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82 } |
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83 |
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84 /** |
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85 The function to register a custom parsing routine in the USB descriptor parser framework. |
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86 |
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87 The routine is registered locally to the current thread, and so if an application wishes |
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88 to perform the same custom parsing in multiple threads, it must call this function with |
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89 the appropriate routine in each thread context. |
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90 |
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91 If the custom routine becomes unapplicable after being registered, the application may |
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92 unregister it using the UsbDescriptorParser::UnregisterCustomParser function. |
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93 @see UsbDescriptorParser::UnregisterCustomParser |
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94 |
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95 @param aParserFunc The routine which will be added to the USB descriptor parsing framework. |
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96 |
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97 @publishedPartner |
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98 @prototype |
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99 */ |
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100 EXPORT_C /*static*/ void UsbDescriptorParser::RegisterCustomParserL(TUsbDescriptorParserL aParserFunc) |
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101 { |
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102 TBool newlyCreatedList = EFalse; |
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103 CUsbCustomDescriptorParserList* parserList = static_cast<CUsbCustomDescriptorParserList*>(Dll::Tls()); |
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104 if(!parserList) |
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105 { |
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106 parserList = CUsbCustomDescriptorParserList::NewL(); |
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107 newlyCreatedList = ETrue; |
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108 CleanupStack::PushL(parserList); |
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109 } |
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110 |
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111 parserList->RegisterParserL(aParserFunc); |
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112 |
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113 if(newlyCreatedList) |
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114 { |
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115 Dll::SetTls(parserList); |
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116 CleanupStack::Pop(parserList); |
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117 } |
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118 } |
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119 |
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120 /** |
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121 The function to unregister a custom parsing routine in the USB descriptor parser framework. |
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122 |
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123 This routine will only unregister the routine from the current thread context. If the routine |
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124 is registered in multiple threads and it is no longer wanted in any thread, an application |
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125 must call this function in each thread context that the routine is registered. |
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126 |
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127 It is safe to call this function even if RegisterCustomParserL has never been called successfully. |
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128 |
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129 @see UsbDescriptorParser::RegisterCustomParserL |
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130 |
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131 @param aParserFunc The routine which will be removed from the USB descriptor parsing framework. |
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132 |
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133 @publishedPartner |
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134 @prototype |
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135 */ |
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136 EXPORT_C /*static*/ void UsbDescriptorParser::UnregisterCustomParser(TUsbDescriptorParserL aParserFunc) |
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137 { |
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138 CUsbCustomDescriptorParserList* parserList = static_cast<CUsbCustomDescriptorParserList*>(Dll::Tls()); |
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139 if(parserList) |
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140 { |
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141 parserList->UnregisterParser(aParserFunc); |
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142 if(parserList->NumOfRegisteredParsers() <= 0) |
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143 { |
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144 Dll::FreeTls(); |
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145 delete parserList; |
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146 } |
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147 } |
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148 } |
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149 |
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150 /*static*/ TUsbGenericDescriptor* UsbDescriptorParser::FindParserAndParseAndCheckL(TPtrC8& aUsbDes, TUsbGenericDescriptor* aPreviousDesc) |
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151 { |
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152 TUsbGenericDescriptor* ret = FindParserAndParseL(aUsbDes, aPreviousDesc); |
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153 // We need to ensure that the parsers have correctly initialised the USB descriptor objects. |
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154 // It is important that we check as it is possible that a custom parser did the parsing. |
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155 __ASSERT_ALWAYS(!ret || (!ret->iParent && !ret->iFirstChild && !ret->iNextPeer), |
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156 UsbDescPanic(UsbdiPanics::EUsbDescNonNullPointersAfterParsing)); |
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157 return ret; |
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158 } |
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159 |
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160 // Utility macro to tidy up the parsing routine. |
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161 #define RETURN_IF_PARSEDL(aRet, aParserL, aUsbDes, aPreviousDesc)\ |
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162 {\ |
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163 aRet = aParserL(aUsbDes, aPreviousDesc);\ |
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164 if(aRet)\ |
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165 {\ |
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166 return aRet;\ |
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167 }\ |
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168 } |
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169 |
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170 /*static*/ TUsbGenericDescriptor* UsbDescriptorParser::FindParserAndParseL(TPtrC8& aUsbDes, TUsbGenericDescriptor* aPreviousDesc) |
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171 { |
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172 // Special termination case. |
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173 if(aUsbDes.Length() == 0) |
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174 { |
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175 return NULL; |
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176 } |
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177 |
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178 TUsbGenericDescriptor* des; |
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179 |
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180 // Try the default parsing routines. |
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181 RETURN_IF_PARSEDL(des, TUsbDeviceDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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182 RETURN_IF_PARSEDL(des, TUsbDeviceQualifierDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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183 RETURN_IF_PARSEDL(des, TUsbConfigurationDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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184 RETURN_IF_PARSEDL(des, TUsbOtherSpeedDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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185 RETURN_IF_PARSEDL(des, TUsbInterfaceAssociationDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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186 RETURN_IF_PARSEDL(des, TUsbInterfaceDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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187 RETURN_IF_PARSEDL(des, TUsbEndpointDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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188 RETURN_IF_PARSEDL(des, TUsbOTGDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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189 RETURN_IF_PARSEDL(des, TUsbStringDescriptor::ParseL, aUsbDes, aPreviousDesc); |
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190 |
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191 // Then we try the custom parsers that have been registered. |
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192 const CUsbCustomDescriptorParserList* parserList = static_cast<const CUsbCustomDescriptorParserList*>(Dll::Tls()); |
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193 if(parserList) |
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194 { |
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195 TInt numOfParsers = parserList->NumOfRegisteredParsers()-1; |
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196 for(TInt index=0; index<numOfParsers; ++index) |
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197 { |
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198 TUsbDescriptorParserL parserL = parserList->RegisteredParser(index); |
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199 RETURN_IF_PARSEDL(des, parserL, aUsbDes, aPreviousDesc); |
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200 } |
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201 } |
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202 |
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203 // Then we try the unknown descriptor parser. |
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204 RETURN_IF_PARSEDL(des, UnknownUsbDescriptorParserL, aUsbDes, aPreviousDesc); |
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205 |
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206 // Otherwise we haven't found anybody to parse the binary data. |
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207 User::Leave(KErrNotFound); // inform caller that there is no parser for the data. |
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208 return NULL; |
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209 } |
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210 |
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211 /*static*/ void UsbDescriptorParser::ParseDescriptorTreeL(TPtrC8& aUsbDes, TUsbGenericDescriptor& aPreviousDesc) |
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212 { |
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213 TUsbGenericDescriptor* desc = &aPreviousDesc; |
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214 while(desc) |
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215 { |
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216 TUsbGenericDescriptor* preDesc = desc; |
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217 desc = FindParserAndParseAndCheckL(aUsbDes, desc); |
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218 if(desc) |
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219 { |
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220 CleanupStack::PushL(desc); |
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221 BuildTreeL(*desc, *preDesc); |
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222 CleanupStack::Pop(desc); |
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223 } |
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224 } |
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225 } |
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226 |
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227 /*static*/ void UsbDescriptorParser::BuildTreeL(TUsbGenericDescriptor& aNewDesc, TUsbGenericDescriptor& aPreviousDesc) |
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228 { |
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229 // We assume that the new descriptor has been properly initialised with NULL pointers. |
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230 __ASSERT_DEBUG(!aNewDesc.iFirstChild && !aNewDesc.iNextPeer && !aNewDesc.iParent, |
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231 UsbDescFault(UsbdiFaults::EUsbDescTreePointersAlreadySet)); |
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232 |
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233 // Find first "top" parent claiming this new descriptor as a child. |
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234 TUsbGenericDescriptor* parent = &aPreviousDesc; |
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235 TUsbGenericDescriptor* topLevel = &aPreviousDesc; |
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236 while(parent) |
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237 { |
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238 if(aNewDesc.IsParent(*parent) || parent->IsChild(aNewDesc)) |
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239 { |
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240 break; // we have found a parent. |
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241 } |
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242 topLevel = parent; // Save the current one for use if we cannot find a parent |
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243 parent = parent->iParent; // Scroll back up the tree. |
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244 } |
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245 __ASSERT_DEBUG(topLevel, UsbDescFault(UsbdiFaults::EUsbDescNoTopLevelDescriptorFound)); |
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246 |
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247 if(parent) |
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248 { |
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249 // We should be able to place the descriptor directly as a child of this descriptor, |
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250 // however it is not that simple because of IADs (Interface Association Descriptors). |
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251 // The ECN states "All of the interface numbers in the set of associated interfaces must be |
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252 // contiguous" meaning that if an IAD has two interfaces starting at 1 then the configuration |
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253 // bundle may have interface descriptors in '1 then 3 then 2' order. As such we need to be able |
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254 // to go backwards to find the most suitable binding. The general way for doing this is to |
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255 // find the right-most, lowest descriptor that descriptor considers a parent. |
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256 // Where the tree is arranged with peers horizontally linked left to |
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257 // right, with children linked vertically top to bottom. |
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258 TUsbGenericDescriptor& suitableParent = FindSuitableParentL(aNewDesc, *parent); |
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259 |
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260 TUsbGenericDescriptor* peer = suitableParent.iFirstChild; |
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261 if(peer) |
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262 { |
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263 TUsbGenericDescriptor* lastPeer; |
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264 do |
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265 { |
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266 lastPeer = peer; |
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267 peer = peer->iNextPeer; |
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268 } |
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269 while(peer); |
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270 lastPeer->iNextPeer = &aNewDesc; |
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271 } |
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272 else |
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273 { |
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274 // we are the first child so just update. |
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275 suitableParent.iFirstChild = &aNewDesc; |
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276 } |
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277 aNewDesc.iParent = &suitableParent; |
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278 } |
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279 else if(aNewDesc.IsPeer(*topLevel) || topLevel->IsPeer(aNewDesc)) |
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280 { |
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281 // There is no explicit parent in the tree so, we may just have a group of top-level peers |
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282 // in the bundle. If the previous descriptor is a peer then we shall just tag on its tier. |
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283 TUsbGenericDescriptor* lastPeer; |
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284 TUsbGenericDescriptor* peer = topLevel; |
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285 do |
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286 { |
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287 lastPeer = peer; |
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288 peer = peer->iNextPeer; |
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289 } |
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290 while(peer); |
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291 lastPeer->iNextPeer = &aNewDesc; |
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292 } |
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293 else |
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294 { |
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295 // The descriptor could not be bound into the tree, indicating that the bundle of descriptors |
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296 // is unvalid. |
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297 User::Leave(KErrUsbBadDescriptorTopology); |
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298 } |
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299 } |
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300 |
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301 /*static*/ TUsbGenericDescriptor& UsbDescriptorParser::FindSuitableParentL(TUsbGenericDescriptor& aNewDesc, TUsbGenericDescriptor& aTopParent) |
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302 { |
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303 // This implements the algorithm to search down from the top parent found in the tree to the right most, lowest descriptor |
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304 // that will accept the new descriptor as a child. |
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305 |
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306 TUsbGenericDescriptor* bestMatch = &aTopParent; |
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307 |
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308 TUsbGenericDescriptor* desc = aTopParent.iFirstChild; |
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309 if(desc) |
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310 { |
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311 // Do a depth first search. |
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312 FOREVER |
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313 { |
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314 // First see if the descriptor is suitable. |
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315 __ASSERT_DEBUG(desc, UsbDescFault(UsbdiFaults::EUsbDescRunOffTree)); |
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316 if(aNewDesc.IsParent(*desc) || desc->IsChild(aNewDesc)) |
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317 { |
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318 bestMatch = desc; |
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319 } |
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320 // Now walk to the next point in the tree. |
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321 if(desc->iFirstChild) |
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322 { |
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323 desc = desc->iFirstChild; |
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324 } |
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325 else if(desc->iNextPeer) |
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326 { |
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327 desc = desc->iNextPeer; |
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328 } |
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329 else |
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330 { |
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331 // We've run to the end of a bottom tier, so go back up. |
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332 do |
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333 { |
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334 __ASSERT_DEBUG(desc->iParent, UsbDescFault(UsbdiFaults::EUsbDescTreeMemberHasNoParent)); |
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335 desc = desc->iParent; |
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336 } |
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337 while(!desc->iNextPeer && desc != &aTopParent); |
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338 if(desc == &aTopParent) |
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339 { |
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340 // This means that we must have got back to the original |
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341 // parent. So we don't do any more. |
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342 break; |
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343 } |
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344 desc = desc->iNextPeer; |
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345 } |
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346 } |
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347 } |
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348 return *bestMatch; |
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349 } |
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350 |
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351 /*static*/ TUsbGenericDescriptor* UsbDescriptorParser::UnknownUsbDescriptorParserL(TPtrC8& aUsbDes, TUsbGenericDescriptor* /*aPreviousDesc*/) |
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352 { |
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353 TUsbGenericDescriptor* unknownDes = NULL; |
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354 |
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355 const TInt KMinUnknownDesLength = 2; // Length and type fields |
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356 if( aUsbDes.Length() >= KMinUnknownDesLength) |
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357 { |
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358 // We require unknown descriptors to have at least the length and type fields. |
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359 // Any more exotic descriptors should have a custom parser for the framework to use. |
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360 TUint8 unknownDesLen = aUsbDes[TUsbGenericDescriptor::KbLengthOffset]; |
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361 |
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362 // Robustness check - check the length field is valid. |
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363 if(aUsbDes.Length() < unknownDesLen || unknownDesLen < KMinUnknownDesLength) |
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364 { |
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365 User::Leave(KErrCorrupt); |
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366 } |
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367 |
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368 unknownDes = new(ELeave) TUsbGenericDescriptor; |
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369 // Set the standard fields |
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370 unknownDes->ibLength = unknownDesLen; |
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371 unknownDes->ibDescriptorType = aUsbDes[TUsbGenericDescriptor::KbDescriptorTypeOffset] ; |
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372 // Set the blob appropriately |
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373 unknownDes->iBlob.Set(aUsbDes.Left(unknownDesLen)); |
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374 // Update the data-left-to-parse Symbian descriptor |
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375 aUsbDes.Set(aUsbDes.Mid(unknownDesLen)); |
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376 } |
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377 |
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378 return unknownDes; |
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379 } |