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1 /* |
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2 * Copyright (c) 2004-2005 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: Formatter classes for encoding/decoding of a bit stream. |
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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 |
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20 #ifndef STREAMFORMATTER_H |
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21 #define STREAMFORMATTER_H |
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22 |
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23 // INCLUDES |
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24 #include <e32std.h> |
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25 |
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26 // CONSTS |
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27 const TInt KBitsIn1Byte = 8; |
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28 |
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29 // CLASS DECLARATION |
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30 |
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31 /** |
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32 * The formatter class that sequentially encodes a bit stream. |
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33 * |
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34 * @lib Mccamrplformat.lib |
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35 * @since Series 60 3.0 |
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36 */ |
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37 class TStreamEncoder |
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38 { |
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39 public: |
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40 |
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41 /** |
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42 * Constructor. |
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43 */ |
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44 TStreamEncoder() : iBuffer( NULL ), iByteIndex( 0 ), iBitIndex( 0 ) |
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45 { }; |
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46 |
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47 /** |
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48 * Destructor. |
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49 */ |
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50 virtual ~TStreamEncoder() { iBuffer = NULL; }; |
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51 |
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52 public: |
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53 |
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54 /** |
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55 * Initialize the stream encoder. |
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56 * This function must be called before calling any other functions. |
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57 * @since Series 60 3.0 |
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58 * @param aBuffer - [input] Pointer to the bit-stream buffer. |
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59 * @param aByteIndex - [input] Starting byte index ( starts from zero ). |
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60 * @param aBitIndex - [input] Starting bit index ( starts from zero ). |
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61 * @return void |
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62 */ |
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63 void Initialize( TUint8* aBuffer, TInt aByteIndex, TInt aBitIndex ); |
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64 |
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65 /** |
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66 * Put a number of bit values ( up to 32 bits ) into the bit-stream |
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67 * buffer at current location. Bits are put starting from MSB of the |
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68 * buffer byte and advancing to LSB. |
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69 * @since Series 60 3.0 |
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70 * @param aValue - [input] Value to put. |
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71 * @param aBitCount - [input] Number of bits to put; between 1 and 32, |
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72 * both inclusive. |
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73 */ |
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74 void Encode( TUint32 aValue, TInt aBitCount ); |
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75 |
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76 /** |
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77 * Put a number of bit values into the bit-stream buffer at current |
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78 * location. |
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79 * @since Series 60 3.0 |
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80 * @param aFromBuffer - [input] Buffer to get byte values from. |
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81 * @param aByteIndex - [input] Starting byte index ( starts from |
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82 * zero ). |
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83 * @param aBitIndex - [input] Starting bit index ( starts from zero ). |
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84 * @param aBitCount - [input] Number of bits to put. |
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85 */ |
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86 void Encode( const TUint8* aFromBuffer, TInt aFromByteIndex, |
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87 TInt aFromBitIndex, TInt aBitCount ); |
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88 |
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89 /** |
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90 * Get the current byte index value. |
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91 * @since Series 60 3.0 |
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92 * @return TInt - Current byte index value. |
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93 */ |
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94 inline TInt ByteIndex() const |
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95 { return iByteIndex; }; |
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96 |
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97 /** |
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98 * Get the current bit index value. |
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99 * @since Series 60 3.0 |
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100 * @return TInt - Current bit index value. |
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101 */ |
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102 inline TInt BitIndex() const |
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103 { return iBitIndex; }; |
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104 |
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105 /** |
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106 * Set the current byte index value. |
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107 * @since Series 60 3.0 |
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108 * @param aByteIndex New byte index |
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109 */ |
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110 inline void SetByteIndex( TInt aByteIndex ) |
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111 { iByteIndex = aByteIndex; }; |
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112 |
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113 /** |
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114 * Set the current bit index value. |
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115 * @since Series 60 3.0 |
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116 * @param aBitIndex New bit index |
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117 */ |
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118 inline void SetBitIndex( TInt aBitIndex ) |
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119 { iBitIndex = aBitIndex; }; |
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120 |
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121 private: |
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122 |
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123 // Pointer to the bit-stream buffer. |
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124 TUint8* iBuffer; |
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125 |
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126 // Current byte index ( starts from zero ) |
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127 TInt iByteIndex; |
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128 |
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129 // Current bit index ( starts from zero ) |
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130 TInt iBitIndex; |
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131 }; |
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132 |
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133 /** |
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134 * The formatter class that sequentially decodes a bit stream. |
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135 * |
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136 * @lib Mccamrplformat.lib |
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137 * @since Series 60 3.0 |
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138 */ |
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139 class TStreamDecoder |
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140 { |
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141 public: |
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142 |
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143 /** |
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144 * Constructor. |
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145 */ |
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146 TStreamDecoder() : iBuffer( NULL ), iByteIndex( 0 ), iBitIndex( 0 ) |
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147 { }; |
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148 |
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149 /** |
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150 * Destructor. |
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151 */ |
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152 virtual ~TStreamDecoder() { iBuffer = NULL; }; |
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153 |
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154 public: |
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155 |
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156 /** |
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157 * Initialize the stream decoder. |
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158 * This function must be called before calling any other functions. |
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159 * @since Series 60 3.0 |
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160 * @param aBuffer - [input] Pointer to the bit-stream buffer. |
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161 * @param aByteIndex - [input] Starting byte index ( starts from |
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162 * zero ). |
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163 * @param aBitIndex - [input] Starting bit index ( starts from zero ). |
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164 */ |
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165 void Initialize( const TUint8* aBuffer, TInt aByteIndex, |
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166 TInt aBitIndex ); |
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167 |
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168 /** |
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169 * Get a number of bit values ( up to 32 bits ) from the bit-stream |
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170 * buffer at current location. Bits are extracted starting from MSB of |
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171 * the buffer byte and advancing to LSB. |
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172 * Returned value: ( MSB )-> bit31, bit30 .... bit1, bit0 <-( LSB, full ) |
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173 * If aBitCount < 32, vacant MSB bits of the returned value are filled |
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174 * with zeros. |
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175 * @since Series 60 3.0 |
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176 * @param aBitCount - [input] Number of bits to get; between 1 and 32, |
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177 * both inclusive. |
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178 * @return TUint32 - Bit values extracted from the buffer; zero if |
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179 * aBitCount is out of range. |
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180 */ |
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181 TUint32 Decode( TInt aBitCount ); |
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182 |
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183 /** |
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184 * Get a number of byte values from the bit-stream buffer at current |
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185 * location. |
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186 * @since Series 60 3.0 |
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187 * @param aToBuffer - [output] Buffer to store byte values. |
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188 * @param aByteIndex - [input] Starting byte index ( starts from |
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189 * zero ). |
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190 * @param aBitIndex - [input] Starting bit index ( starts from zero ). |
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191 * @param aBitCount - [input] Number of bits to put. |
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192 */ |
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193 void Decode( TUint8* aToBuffer, TInt aToByteIndex, TInt aToBitIndex, |
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194 TInt aBitCount ); |
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195 |
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196 /** |
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197 * Get the current byte index value. |
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198 * @since Series 60 3.0 |
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199 * @return TInt - Current byte index value. |
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200 */ |
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201 inline TInt ByteIndex() const |
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202 { return iByteIndex; }; |
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203 |
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204 /** |
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205 * Get the current bit index value. |
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206 * @since Series 60 3.0 |
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207 * @return TInt - Current bit index value. |
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208 */ |
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209 inline TInt BitIndex() const |
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210 { return iBitIndex; }; |
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211 |
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212 /** |
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213 * Set the current byte index value. |
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214 * @since Series 60 3.0 |
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215 * @param aByteIndex New byte index |
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216 */ |
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217 inline void SetByteIndex( TInt aByteIndex ) |
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218 { iByteIndex = aByteIndex; }; |
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219 |
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220 /** |
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221 * Set the current bit index value. |
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222 * @since Series 60 3.0 |
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223 * @param aBitIndex New bit index |
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224 */ |
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225 inline void SetBitIndex( TInt aBitIndex ) |
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226 { iBitIndex = aBitIndex; }; |
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227 |
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228 private: |
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229 |
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230 // Pointer to the bit-stream buffer. |
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231 const TUint8* iBuffer; |
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232 |
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233 // Current byte index ( starts from zero ) |
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234 TInt iByteIndex; |
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235 |
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236 // Current bit index ( starts from zero ) |
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237 TInt iBitIndex; |
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238 }; |
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239 |
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240 #endif // STREAMFORMATTER_H |