mirror of
https://github.com/dwsJason/gsla.git
synced 2024-12-18 00:29:17 +00:00
remove use of vector template, and stop copying data around that doesn't need copied (substantially speeds up the code), even though we're still brute force
This commit is contained in:
JASON-6700K\jandersen
parent
553c5775a9
commit
d28efbc390
130
source/lzb.cpp
130
source/lzb.cpp
@ -4,42 +4,52 @@
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#include "lzb.h"
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#include <stdio.h>
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#include <vector>
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#include <string.h>
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#include "bctypes.h"
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#define DICTIONARY_SIZE (32 * 1024)
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#define MAX_DICTIONARY_SIZE (32 * 1024)
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//
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// Yes This is a 32K Buffer, of bytes, with no structure to it
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//
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static unsigned char Dictionary[ DICTIONARY_SIZE ];
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static unsigned char *pDictionary = nullptr;
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struct DataString {
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int size;
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unsigned char *pData;
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};
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static int AddDictionary(const DataString& data, int dictionarySize);
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static int EmitLiteral(unsigned char *pDest, DataString& data);
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static int ConcatLiteral(unsigned char *pDest, DataString& data);
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static int EmitReference(unsigned char *pDest, int dictionaryOffset, DataString& data);
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static int DictionaryMatch(const DataString& data, int dictionarySize);
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static int AddDictionary(const std::vector<unsigned char>&data, int dictionarySize);
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static int EmitLiteral(unsigned char *pDest, std::vector<unsigned char>& data);
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static int ConcatLiteral(unsigned char *pDest, std::vector<unsigned char>& data);
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static int EmitReference(unsigned char *pDest, int dictionaryOffset, std::vector<unsigned char>& data);
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static int DictionaryMatch(const std::vector<unsigned char>& data, int dictionarySize);
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int LZB_Compress(unsigned char* pDest, unsigned char* pSource, int sourceSize)
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{
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printf("LZB_Compress %d bytes\n", sourceSize);
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// anything less than 3 bytes, is going to be a literal match
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// Initialize Dictionary
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int bytesInDictionary = 0; // eventually add the ability to start with the dictionary filled
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pDictionary = pSource;
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int processedBytes = 0;
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int bytesInDictionary = 0;
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int bytesEmitted = 0;
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// dumb last emit is a literal stuff
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bool bLastEmitIsLiteral = false;
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int lastEmittedLiteralOffset = 0;
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std::vector<unsigned char> candidate_data;
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DataString candidate_data;
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candidate_data.pData = pSource;
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candidate_data.size = 0;
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while (processedBytes < sourceSize)
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{
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unsigned char byte_data = pSource[ processedBytes++ ];
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candidate_data.push_back(byte_data);
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// Add a byte to the candidate_data, also tally number of processed
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processedBytes++;
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candidate_data.size++;
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// Basic Flow Idea Here
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// If there's a match, then add to the candidate data, and see if
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@ -49,9 +59,6 @@ int LZB_Compress(unsigned char* pDest, unsigned char* pSource, int sourceSize)
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// else emit what we have as a literal
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// (KMP is probably the last planned optmization here)
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@ -60,21 +67,23 @@ int LZB_Compress(unsigned char* pDest, unsigned char* pSource, int sourceSize)
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if (DictionaryMatch(candidate_data, bytesInDictionary) < 0)
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{
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// Was there a dictionary match
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std::vector<unsigned char> prev_data = candidate_data;
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prev_data.pop_back();
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int MatchOffset = DictionaryMatch(prev_data, bytesInDictionary);
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// Previous Data, we can't get here with candidate_data.size == 0
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// this is an opportunity to use an assert
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candidate_data.size--;
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if ((MatchOffset >= 0) && prev_data.size() > 3)
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int MatchOffset = DictionaryMatch(candidate_data, bytesInDictionary);
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if ((MatchOffset >= 0) && candidate_data.size > 3)
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{
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bytesInDictionary = AddDictionary(prev_data, bytesInDictionary);
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bytesEmitted += EmitReference(pDest + bytesEmitted, MatchOffset, prev_data);
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candidate_data[0] = candidate_data[ candidate_data.size() - 1 ];
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candidate_data.resize(1);
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processedBytes--;
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bytesInDictionary = AddDictionary(candidate_data, bytesInDictionary);
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bytesEmitted += EmitReference(pDest + bytesEmitted, MatchOffset, candidate_data);
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bLastEmitIsLiteral = false;
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}
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else
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{
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candidate_data.size++;
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// Add Dictionary
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bytesInDictionary = AddDictionary(candidate_data, bytesInDictionary);
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@ -94,12 +103,12 @@ int LZB_Compress(unsigned char* pDest, unsigned char* pSource, int sourceSize)
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}
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}
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if (candidate_data.size() > 0)
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if (candidate_data.size > 0)
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{
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int MatchOffset = DictionaryMatch(candidate_data, bytesInDictionary);
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if ((MatchOffset >=0) && candidate_data.size() > 2)
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if ((MatchOffset >=0) && candidate_data.size > 2)
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{
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bytesInDictionary = AddDictionary(candidate_data, bytesInDictionary);
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bytesEmitted += EmitReference(pDest + bytesEmitted, MatchOffset, candidate_data);
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@ -127,14 +136,15 @@ int LZB_Compress(unsigned char* pDest, unsigned char* pSource, int sourceSize)
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//------------------------------------------------------------------------------
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// Return new dictionarySize
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static int AddDictionary(const std::vector<unsigned char>&data, int dictionarySize)
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static int AddDictionary(const DataString& data, int dictionarySize)
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{
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int dataIndex = 0;
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//int dataIndex = 0;
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//while ((dictionarySize < MAX_DICTIONARY_SIZE) && (dataIndex < data.size))
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//{
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// pDictionary[ dictionarySize++ ] = data.pData[ dataIndex++ ];
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//}
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while ((dictionarySize < DICTIONARY_SIZE) && (dataIndex < data.size()))
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{
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Dictionary[ dictionarySize++ ] = data[ dataIndex++ ];
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}
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dictionarySize += data.size;
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return dictionarySize;
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}
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@ -145,11 +155,11 @@ static int AddDictionary(const std::vector<unsigned char>&data, int dictionarySi
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//
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// -1 means, no match
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//
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static int DictionaryMatch(const std::vector<unsigned char>& data, int dictionarySize)
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static int DictionaryMatch(const DataString& data, int dictionarySize)
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{
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if( (0 == dictionarySize ) ||
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(0 == data.size()) ||
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(data.size() > 16384) ) // 16384 is largest string copy we can encode
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(0 == data.size) ||
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(data.size > 16384) ) // 16384 is largest string copy we can encode
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{
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return -1;
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}
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@ -168,9 +178,9 @@ static int DictionaryMatch(const std::vector<unsigned char>& data, int dictionar
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bool bMatch = true;
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int pattern_start = dictionarySize - pattern_size;
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for (int dataIndex = 0; dataIndex < data.size(); ++dataIndex)
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for (int dataIndex = 0; dataIndex < data.size; ++dataIndex)
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{
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if (data[ dataIndex ] == Dictionary[ pattern_start + (dataIndex % pattern_size) ])
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if (data.pData[ dataIndex ] == pDictionary[ pattern_start + (dataIndex % pattern_size) ])
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continue;
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bMatch = false;
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@ -185,7 +195,7 @@ static int DictionaryMatch(const std::vector<unsigned char>& data, int dictionar
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}
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}
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if (dictionarySize < data.size())
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if (dictionarySize < data.size)
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{
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return -1;
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}
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@ -195,12 +205,12 @@ static int DictionaryMatch(const std::vector<unsigned char>& data, int dictionar
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int result = -1;
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// Check the dictionary for a match, brute force
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for (int idx = 0; idx <= (dictionarySize-data.size()); ++idx)
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for (int idx = 0; idx <= (dictionarySize-data.size); ++idx)
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{
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bool bMatch = true;
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for (int dataIdx = 0; dataIdx < data.size(); ++dataIdx)
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for (int dataIdx = 0; dataIdx < data.size; ++dataIdx)
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{
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if (data[ dataIdx ] == Dictionary[ idx + dataIdx ])
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if (data.pData[ dataIdx ] == pDictionary[ idx + dataIdx ])
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continue;
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bMatch = false;
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@ -221,10 +231,10 @@ static int DictionaryMatch(const std::vector<unsigned char>& data, int dictionar
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//
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// Emit a literal, that appends itself to an existing literal
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//
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static int ConcatLiteral(unsigned char *pDest, std::vector<unsigned char>& data)
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static int ConcatLiteral(unsigned char *pDest, DataString& data)
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{
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// Return Size
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int outSize = (int)data.size();
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int outSize = (int)data.size;
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int opCode = pDest[0];
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opCode |= (int)(((pDest[1])&0x7F)<<8);
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@ -239,53 +249,59 @@ static int ConcatLiteral(unsigned char *pDest, std::vector<unsigned char>& data)
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pDest += skip;
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// Literal Data
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for (int idx = 0; idx < data.size(); ++idx)
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for (int idx = 0; idx < data.size; ++idx)
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{
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*pDest++ = data[ idx ];
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*pDest++ = data.pData[ idx ];
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}
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data.clear();
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// Clear
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data.pData += data.size;
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data.size = 0;
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return outSize;
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}
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//------------------------------------------------------------------------------
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static int EmitLiteral(unsigned char *pDest, std::vector<unsigned char>& data)
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static int EmitLiteral(unsigned char *pDest, DataString& data)
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{
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// Return Size
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int outSize = 2 + (int)data.size();
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int outSize = 2 + (int)data.size;
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// Opcode
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*pDest++ = (unsigned char)(data.size() & 0xFF);
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*pDest++ = (unsigned char)((data.size() >> 8) & 0x7F);
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*pDest++ = (unsigned char)(data.size & 0xFF);
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*pDest++ = (unsigned char)((data.size >> 8) & 0x7F);
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// Literal Data
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for (int idx = 0; idx < data.size(); ++idx)
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for (int idx = 0; idx < data.size; ++idx)
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{
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*pDest++ = data[ idx ];
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*pDest++ = data.pData[ idx ];
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}
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data.clear();
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// Clear
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data.pData += data.size;
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data.size = 0;
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return outSize;
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}
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//------------------------------------------------------------------------------
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static int EmitReference(unsigned char *pDest, int dictionaryOffset, std::vector<unsigned char>& data)
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static int EmitReference(unsigned char *pDest, int dictionaryOffset, DataString& data)
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{
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// Return Size
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int outSize = 2 + 2;
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// Opcode
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*pDest++ = (unsigned char)(data.size() & 0xFF);
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*pDest++ = (unsigned char)((data.size() >> 8) & 0x7F) | 0x80;
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*pDest++ = (unsigned char)(data.size & 0xFF);
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*pDest++ = (unsigned char)((data.size >> 8) & 0x7F) | 0x80;
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*pDest++ = (unsigned char)(dictionaryOffset & 0xFF);
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*pDest++ = (unsigned char)((dictionaryOffset>>8) & 0xFF);
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data.clear();
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// Clear
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data.pData += data.size;
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data.size = 0;
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return outSize;
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}
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