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https://github.com/DarkflameUniverse/DarkflameServer.git
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59 lines
2.0 KiB
C++
59 lines
2.0 KiB
C++
#include "DataCompressor.h"
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#include "DS_HuffmanEncodingTree.h"
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#include <assert.h>
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#include <string.h> // Use string.h rather than memory.h for a console
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void DataCompressor::Compress( unsigned char *userData, unsigned sizeInBytes, RakNet::BitStream * output )
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{
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// Don't use this for small files as you will just make them bigger!
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assert(sizeInBytes > 2048);
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unsigned int frequencyTable[ 256 ];
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unsigned int i;
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memset(frequencyTable,0,256*sizeof(unsigned int));
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for (i=0; i < sizeInBytes; i++)
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++frequencyTable[userData[i]];
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HuffmanEncodingTree tree;
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BitSize_t writeOffset1, writeOffset2, bitsUsed1, bitsUsed2;
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tree.GenerateFromFrequencyTable(frequencyTable);
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output->WriteCompressed(sizeInBytes);
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for (i=0; i < 256; i++)
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output->WriteCompressed(frequencyTable[i]);
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output->AlignWriteToByteBoundary();
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writeOffset1=output->GetWriteOffset();
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output->Write((unsigned int)0); // Dummy value
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bitsUsed1=output->GetNumberOfBitsUsed();
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tree.EncodeArray(userData, sizeInBytes, output);
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bitsUsed2=output->GetNumberOfBitsUsed();
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writeOffset2=output->GetWriteOffset();
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output->SetWriteOffset(writeOffset1);
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output->Write(bitsUsed2-bitsUsed1); // Go back and write how many bits were used for the encoding
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output->SetWriteOffset(writeOffset2);
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}
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unsigned DataCompressor::DecompressAndAllocate( RakNet::BitStream * input, unsigned char **output )
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{
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HuffmanEncodingTree tree;
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unsigned int bitsUsed, destinationSizeInBytes, decompressedBytes;
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unsigned int frequencyTable[ 256 ];
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unsigned i;
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input->ReadCompressed(destinationSizeInBytes);
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for (i=0; i < 256; i++)
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input->ReadCompressed(frequencyTable[i]);
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input->AlignReadToByteBoundary();
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if (input->Read(bitsUsed)==false)
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{
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// Read error
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#ifdef _DEBUG
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assert(0);
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#endif
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return 0;
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}
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*output = (unsigned char*) rakMalloc(destinationSizeInBytes);
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tree.GenerateFromFrequencyTable(frequencyTable);
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decompressedBytes=tree.DecodeArray(input, bitsUsed, destinationSizeInBytes, *output );
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assert(decompressedBytes==destinationSizeInBytes);
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return destinationSizeInBytes;
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}
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