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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: PayloadFormat plugin capable to read RTP payload containing |
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15 * AMR audio. |
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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 |
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21 |
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22 // INCLUDE FILES |
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23 #include "streamformatter.h" |
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24 |
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25 // CONSTANTS |
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26 const TInt KBitsIn4Bytes = 32; |
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27 const TUint8 KZeroMask = 0xFF; |
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28 const TInt KBitIndex7 = 7; |
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29 |
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30 // ============================ MEMBER FUNCTIONS =============================== |
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31 |
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32 // ----------------------------------------------------------------------------- |
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33 // TStreamEncoder::Initialize |
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34 // Initialize the stream encoder. |
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35 // ----------------------------------------------------------------------------- |
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36 // |
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37 void TStreamEncoder::Initialize( TUint8* aBuffer, TInt aByteIndex, TInt aBitIndex ) |
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38 { |
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39 iBuffer = aBuffer; |
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40 iByteIndex = aByteIndex; |
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41 iBitIndex = aBitIndex; |
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42 }; |
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43 |
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44 // ----------------------------------------------------------------------------- |
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45 // TStreamEncoder::Encode |
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46 // Put a number of bit values ( up to 32 bits ) into the bit-stream buffer |
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47 // ----------------------------------------------------------------------------- |
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48 // |
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49 void TStreamEncoder::Encode( TUint32 aValue, TInt aBitCount ) |
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50 { |
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51 // Bit count has to be between 1 and 32 so if number of bits is out of range |
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52 // return from here |
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53 if ( aBitCount < 1 || aBitCount > KBitsIn4Bytes ) |
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54 { |
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55 return; |
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56 } |
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57 |
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58 TInt bitCount = aBitCount; |
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59 TInt vacantBits; |
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60 TInt bitsWritten; |
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61 TUint32 oldValue; |
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62 TUint32 newValue; |
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63 TUint8* p; |
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64 |
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65 while ( bitCount > 0 ) |
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66 { |
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67 p = iBuffer + iByteIndex; |
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68 vacantBits = KBitsIn1Byte - iBitIndex; |
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69 |
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70 if ( bitCount >= vacantBits ) |
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71 { |
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72 // get old value and zero out vacant bits |
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73 oldValue = ( *p ) & ( KZeroMask << vacantBits ); |
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74 |
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75 newValue = ( ( bitCount - vacantBits ) < KBitsIn4Bytes ) ? |
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76 TUint8( ( aValue >> ( bitCount - vacantBits ) ) ) : 0; |
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77 |
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78 bitsWritten = vacantBits; |
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79 } |
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80 else |
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81 { |
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82 oldValue = ( *p ) |
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83 & ( ( KZeroMask << vacantBits ) |
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84 | ( KZeroMask >> ( KBitsIn1Byte - vacantBits + bitCount ) ) ); |
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85 newValue = TUint8( ( aValue << ( vacantBits-bitCount ) ) ); |
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86 bitsWritten = bitCount; |
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87 } |
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88 |
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89 // zero out unwanted bits |
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90 newValue &= ( KZeroMask ) >> ( iBitIndex ); |
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91 // write the byte |
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92 *p = TUint8( ( oldValue | newValue ) ); |
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93 |
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94 // update variables |
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95 bitCount -= bitsWritten; |
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96 iBitIndex += bitsWritten; |
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97 if ( iBitIndex > KBitIndex7 ) |
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98 { |
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99 iBitIndex &= KBitIndex7; |
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100 iByteIndex += 1; |
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101 } |
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102 } |
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103 }; |
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104 |
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105 // ----------------------------------------------------------------------------- |
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106 // TStreamEncoder::Encode |
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107 // Put a number of bit values into the bit-stream buffer at current location. |
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108 // ----------------------------------------------------------------------------- |
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109 // |
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110 void TStreamEncoder::Encode( const TUint8* aFromBuffer, TInt aFromByteIndex, |
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111 TInt aFromBitIndex, TInt aBitCount ) |
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112 { |
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113 if ( aFromBitIndex == 0 && iBitIndex == 0 ) |
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114 { |
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115 // Mem::Copy is applicable |
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116 TUint8* desBuffer = iBuffer + iByteIndex; |
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117 const TUint8* srcBuffer = aFromBuffer + aFromByteIndex; |
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118 |
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119 TInt byteLen = aBitCount / KBitsIn1Byte; |
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120 TInt bitsLeft = aBitCount % KBitsIn1Byte; |
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121 |
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122 Mem::Copy( desBuffer, srcBuffer, byteLen ); |
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123 iByteIndex += byteLen; |
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124 |
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125 if ( bitsLeft != 0 ) |
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126 { |
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127 TUint32 value; |
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128 TStreamDecoder decoder; |
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129 decoder.Initialize( aFromBuffer, aFromByteIndex + byteLen, aFromBitIndex ); |
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130 value = decoder.Decode( bitsLeft ); |
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131 Encode( value, bitsLeft ); |
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132 } |
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133 |
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134 return; |
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135 } |
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136 |
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137 // Note that Mem::Copy is not applicable, have to do bit shifting |
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138 TInt bitFilled = 0; |
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139 TUint32 value; |
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140 TStreamDecoder decoder; |
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141 decoder.Initialize( aFromBuffer, aFromByteIndex, aFromBitIndex ); |
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142 |
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143 while ( bitFilled < aBitCount ) |
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144 { |
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145 if ( aBitCount - bitFilled < KBitsIn4Bytes ) |
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146 { |
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147 value = decoder.Decode( aBitCount - bitFilled ); |
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148 Encode( value, ( aBitCount - bitFilled ) ); |
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149 bitFilled = aBitCount; |
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150 } |
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151 else |
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152 { |
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153 value = decoder.Decode( KBitsIn4Bytes ); |
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154 Encode( value, KBitsIn4Bytes ); |
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155 bitFilled += KBitsIn4Bytes; |
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156 } |
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157 } |
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158 }; |
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159 |
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160 // ----------------------------------------------------------------------------- |
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161 // TStreamDecoder::Initialize |
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162 // Initialize the stream decoder. |
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163 // ----------------------------------------------------------------------------- |
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164 // |
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165 void TStreamDecoder::Initialize( const TUint8* aBuffer, TInt aByteIndex, |
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166 TInt aBitIndex ) |
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167 { |
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168 iBuffer = aBuffer; |
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169 iByteIndex = aByteIndex; |
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170 iBitIndex = aBitIndex; |
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171 }; |
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172 |
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173 // ----------------------------------------------------------------------------- |
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174 // TStreamDecoder::Decode |
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175 // Get a number of bit values ( up to 32 bits ) from the bit-stream buffer at |
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176 // current location. |
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177 // ----------------------------------------------------------------------------- |
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178 // |
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179 TUint32 TStreamDecoder::Decode( TInt aBitCount ) |
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180 { |
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181 // Bit count has to be between 1 and 32 so if number of bits is out of range |
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182 // return from here |
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183 if ( aBitCount < 1 || aBitCount > KBitsIn4Bytes ) |
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184 { |
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185 return 0; |
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186 } |
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187 |
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188 TInt bitCount = aBitCount; |
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189 TInt availableBits; |
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190 TInt bitsRead; |
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191 TUint8* p; |
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192 TUint32 temp; |
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193 TUint32 value = 0; |
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194 |
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195 while ( bitCount > 0 ) |
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196 { |
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197 p = const_cast<TUint8*>( iBuffer ) + iByteIndex; |
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198 availableBits = KBitsIn1Byte - iBitIndex; |
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199 |
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200 // read one byte and zero out unwanted bits |
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201 temp = ( *p ) & ( KZeroMask >> iBitIndex ); |
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202 |
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203 // update return value |
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204 if ( bitCount >= availableBits ) |
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205 { |
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206 value = TUint8( temp ) | ( value<<availableBits ); |
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207 bitsRead = availableBits; |
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208 } |
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209 else |
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210 { |
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211 value = TUint8( ( temp >> ( availableBits - bitCount ) ) ) | ( value << bitCount ); |
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212 bitsRead = bitCount; |
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213 } |
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214 |
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215 // update variables |
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216 bitCount -= bitsRead; |
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217 iBitIndex += bitsRead; |
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218 if ( iBitIndex > KBitIndex7 ) |
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219 { |
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220 iBitIndex &= KBitIndex7; |
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221 iByteIndex += 1; |
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222 } |
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223 } |
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224 |
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225 return value; |
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226 }; |
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227 |
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228 // ----------------------------------------------------------------------------- |
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229 // TStreamDecoder::Decode |
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230 // Get a number of byte values from the bit-stream buffer at current location. |
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231 // ----------------------------------------------------------------------------- |
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232 // |
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233 void TStreamDecoder::Decode( TUint8* aToBuffer, TInt aToByteIndex, |
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234 TInt aToBitIndex, TInt aBitCount ) |
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235 { |
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236 if ( aToBitIndex == 0 && iBitIndex == 0 ) |
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237 { |
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238 // Mem::Copy is applicable |
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239 TUint8* desBuffer = aToBuffer + aToByteIndex; |
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240 const TUint8* srcBuffer = iBuffer + iByteIndex; |
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241 |
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242 TInt byteLen = aBitCount / KBitsIn1Byte; |
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243 TInt bitsLeft = aBitCount % KBitsIn1Byte; |
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244 |
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245 Mem::Copy( desBuffer, srcBuffer, byteLen ); |
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246 iByteIndex += byteLen; |
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247 |
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248 if ( bitsLeft != 0 ) |
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249 { |
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250 TUint32 value; |
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251 TStreamEncoder encoder; |
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252 encoder.Initialize( aToBuffer, aToByteIndex + byteLen, aToBitIndex ); |
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253 value = Decode( bitsLeft ); |
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254 encoder.Encode( value, bitsLeft ); |
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255 } |
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256 |
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257 return; |
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258 } |
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259 |
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260 // Note that Mem::Copy is not applicable, have to do bit shifting |
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261 TInt bitFilled = 0; |
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262 TUint32 value; |
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263 TStreamEncoder encoder; |
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264 encoder.Initialize( aToBuffer, aToByteIndex, aToBitIndex ); |
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265 |
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266 while ( bitFilled < aBitCount ) |
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267 { |
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268 // Check if number of remaining bits is less than 32. |
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269 if ( aBitCount - bitFilled < KBitsIn4Bytes ) |
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270 { |
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271 value = Decode( aBitCount - bitFilled ); |
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272 encoder.Encode( value, ( aBitCount - bitFilled ) ); |
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273 bitFilled = aBitCount; |
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274 } |
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275 else |
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276 { |
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277 value = Decode( KBitsIn4Bytes ); |
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278 encoder.Encode( value, KBitsIn4Bytes ); |
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279 bitFilled += KBitsIn4Bytes; |
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280 } |
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281 } |
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282 }; |
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283 |
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284 // ========================== OTHER EXPORTED FUNCTIONS ========================= |
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285 |
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286 // End of File |