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1 /* |
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2 * Copyright (c) 2004-2007 Nokia Corporation and/or its subsidiary(-ies). |
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3 * All rights reserved. |
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4 * This component and the accompanying materials are made available |
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5 * under the terms of "Eclipse Public License v1.0" |
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6 * which accompanies this distribution, and is available |
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7 * at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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8 * |
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9 * Initial Contributors: |
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10 * Nokia Corporation - initial contribution. |
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11 * |
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12 * Contributors: |
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13 * |
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14 * Description: Item implementation |
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15 * |
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16 */ |
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17 |
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18 |
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19 // References: |
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20 // |
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21 // [1] USB Device Class Definition for Human Interface Devices (HID), |
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22 // Firmware Specification, Version 1.11, USB Implementers' Forum, |
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23 // June 2001 |
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24 // |
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25 // ---------------------------------------------------------------------- |
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26 |
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27 #include <e32std.h> |
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28 |
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29 #include "hiditem.h" |
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30 #include "hidparser.h" |
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31 |
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32 const TInt KSizeMask = 0x03; |
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33 const TInt KTypeMask = 0x03; |
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34 const TInt KTypePosn = 2; |
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35 const TInt KTagMask = 0x0F; |
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36 const TInt KTagPosn = 4; |
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37 const TInt KLongItemId = 0xfe; |
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38 const TInt KMaxItemlength = 4; |
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39 const TInt KSizeThree = 3; |
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40 const TInt KSizeFour = 4; |
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41 const TInt KLongItemMin = 3; |
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42 |
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43 |
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44 // ======== MEMBER FUNCTIONS ======== |
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45 |
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46 // --------------------------------------------------------------------------- |
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47 // Constructor |
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48 // --------------------------------------------------------------------------- |
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49 // |
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50 TItem::TItem(const TDesC8& aRawData) |
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51 : iRawData(aRawData) |
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52 { |
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53 if (aRawData.Length() < 1) |
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54 { |
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55 return; |
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56 } |
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57 TBool isShortItem = (aRawData[0] != KLongItemId); |
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58 |
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59 if (isShortItem) |
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60 { |
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61 // +----+----+----+----+----+----+----+----+ |
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62 // | Tag | Type | Size | [data...] |
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63 // | . . . | . | . | |
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64 // +----+----+----+----+----+----+----+----+ |
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65 // 7 6 5 4 3 2 1 0 |
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66 // |
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67 // A short item is followed by 0, 1, 2 or 4 bytes of data, as |
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68 // specified in the size field. See [1], Section 6.2.2.2. |
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69 iSize = aRawData[0] & KSizeMask; |
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70 if (iSize == KSizeThree) |
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71 { |
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72 iSize = KSizeFour; |
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73 } |
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74 iType = static_cast<TItemType>((aRawData[0] >> KTypePosn) & KTypeMask); |
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75 iTag = (aRawData[0] >> KTagPosn) & KTagMask; |
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76 iDataOffset = 1; |
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77 } |
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78 else |
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79 { |
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80 // Byte 0 Byte 1 Byte 2 |
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81 // +------+------+------+ +-----------+ +-----------+ |
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82 // | Tag | Type | Size | | Data size | | Long item | [data...] |
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83 // | 1111 | 11 | 10 | | (0-255) | | tag | |
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84 // +------+------+------+ +-----------+ +-----------+ |
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85 // 7654 32 10 |
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86 // |
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87 // A long item is followed by 0-255 bytes of data, as specified |
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88 // in the data size byte. See [1], Section 6.2.2.3. |
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89 |
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90 iType = EReserved; |
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91 |
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92 if (aRawData.Length() > KLongItemMin) |
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93 { |
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94 iSize = aRawData[1]; |
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95 iTag = aRawData[2]; |
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96 iDataOffset = KLongItemMin; |
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97 } |
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98 else |
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99 { |
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100 iSize = 0; |
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101 iTag = 0; |
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102 iDataOffset = 0; |
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103 } |
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104 } |
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105 |
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106 #ifdef DBG_ACTIVE |
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107 for (TInt i=0; (i<aRawData.Length()) && (i<(iSize+iDataOffset)); ++i) |
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108 { |
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109 RDebug::Print(_L("aRawData[%d] = 0x%02x"), i, aRawData[i]); |
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110 } |
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111 #endif |
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112 } |
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113 |
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114 // --------------------------------------------------------------------------- |
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115 // DataSize() |
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116 // --------------------------------------------------------------------------- |
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117 // |
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118 TInt TItem::DataSize() const |
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119 { |
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120 return iSize; |
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121 } |
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122 |
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123 // --------------------------------------------------------------------------- |
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124 // Tag() |
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125 // --------------------------------------------------------------------------- |
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126 // |
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127 TInt TItem::Tag() const |
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128 { |
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129 return iTag; |
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130 } |
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131 |
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132 // --------------------------------------------------------------------------- |
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133 // Data() |
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134 // --------------------------------------------------------------------------- |
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135 // |
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136 TUint32 TItem::Data() const |
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137 { |
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138 TInt size = DataSize(); |
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139 |
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140 // Calling Data() makes no sense for long items that have a data |
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141 // size over 4 bytes, as it only returns a TUint32: |
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142 // |
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143 if (size > KMaxItemlength) |
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144 { |
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145 size = KMaxItemlength; |
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146 } |
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147 |
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148 // Ensure we don't overrun the source buffer: |
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149 // |
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150 if (size > (iRawData.Length() - 1)) |
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151 { |
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152 size = iRawData.Length() - 1; |
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153 } |
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154 |
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155 // Concatenate each byte into a TUint32. Note that this function must |
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156 // return zero if the data size is zero (see Parser.cpp, MainItemL()). |
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157 // |
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158 TUint32 tagData = 0; |
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159 for (TInt i=0; i<size; ++i) |
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160 { |
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161 tagData |= (iRawData[1 + i] << (KSizeOfByte*i)); |
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162 } |
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163 |
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164 return tagData; |
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165 } |
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166 |
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167 // --------------------------------------------------------------------------- |
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168 // SignedData() |
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169 // --------------------------------------------------------------------------- |
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170 // |
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171 TInt32 TItem::SignedData() const |
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172 { |
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173 TUint32 data = Data(); |
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174 |
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175 // For 8 and 16 bit negative values, we need to |
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176 // sign extend to 32-bits: |
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177 // |
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178 if ((DataSize() == 1) && (data & 0x80)) |
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179 { |
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180 data |= 0xffffff00; |
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181 } |
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182 if ((DataSize() == 2) && (data & 0x8000)) |
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183 { |
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184 data |= 0xffff0000; |
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185 } |
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186 |
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187 // Note that this assumes that the machine uses 2s complement |
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188 // representation internally. All current Symbian devices do, |
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189 // including ARM devices and the WINS emulator. This is almost |
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190 // certain to remain the case in the future. |
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191 // |
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192 return static_cast<TInt32>(data); |
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193 } |
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194 |
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195 // --------------------------------------------------------------------------- |
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196 // Operator [] |
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197 // --------------------------------------------------------------------------- |
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198 // |
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199 TUint8 TItem::operator[](TInt aIndex) const |
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200 { |
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201 |
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202 TUint8 value = 0; |
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203 if ((aIndex >= 0) && (aIndex < iSize)) |
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204 { |
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205 value = iRawData[iDataOffset + aIndex]; |
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206 } |
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207 return value; |
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208 } |
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209 |
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210 // --------------------------------------------------------------------------- |
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211 // Type() |
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212 // --------------------------------------------------------------------------- |
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213 // |
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214 TItem::TItemType TItem::Type() const |
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215 { |
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216 return iType; |
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217 } |
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218 |
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219 // --------------------------------------------------------------------------- |
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220 // IsMain() |
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221 // --------------------------------------------------------------------------- |
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222 // |
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223 TBool TItem::IsMain() const |
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224 { |
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225 return iType == TItem::EMain; |
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226 } |
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227 |
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228 // --------------------------------------------------------------------------- |
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229 // IsLocal() |
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230 // --------------------------------------------------------------------------- |
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231 // |
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232 TBool TItem::IsLocal() const |
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233 { |
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234 return iType == TItem::ELocal; |
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235 } |
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236 |
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237 // --------------------------------------------------------------------------- |
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238 // IsGlobal() |
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239 // --------------------------------------------------------------------------- |
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240 // |
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241 TBool TItem::IsGlobal() const |
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242 { |
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243 return iType == TItem::EGlobal; |
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244 } |
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245 |
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246 // --------------------------------------------------------------------------- |
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247 // IsLong() |
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248 // --------------------------------------------------------------------------- |
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249 // |
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250 TBool TItem::IsLong() const |
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251 { |
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252 return iType == TItem::EReserved; |
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253 } |
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254 |
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255 // --------------------------------------------------------------------------- |
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256 // ItemSize() |
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257 // --------------------------------------------------------------------------- |
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258 // |
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259 TInt TItem::ItemSize() const |
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260 { |
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261 return iSize + iDataOffset; |
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262 } |
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263 |