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void HuffmanCoding::decompress(string input, string output)
{
//initalize variables
codeTree = new mergingTree<mergingType>;
inFile = input;
outFile = output;
fileBuffer = new int[1000];
fileBuffer2 = new int[1000];
counts = new int[256];
fileBufferSize = fileBufferSize2 = bufferSize = 0;
readChars = 0;
readDone = false;
for(int i = 0; i < 256; i++)
counts[i] = 0;
//read file's signature
cout << "Reading file's signature..." << flush;
readSignature();
//Create output file
ofstream outputfile(outFile.c_str(),ios::out | ios::binary);
if(!outputfile.is_open())
throw runtime_error( "Cannot create the output file!");
outputfile.close();
//insert nonzero counts into mergingTree's heap
// and set other variables
cout << "Done\nSetting necessary variables for decompressing..." << flush;
int nonzeros = 0;
for(int i = 0; i < 256; i++)
{
if(counts[i] != 0)
{
nonzeros++;
mergingType tmp(i,counts[i]);
codeTree->insertNode(tmp);
}
}
//get file's size and precent to show the progress
unsigned long inputfilesize = fileSize(),
currpos = 0, percent, outputfilesize = 0;
inputfilesize -= ( (nonzeros * 8) + 5 );
percent = inputfilesize / 100;
int curper = 0;
//create mergingTree's tree
// and also get a copy of mergingTree's root
codeTree->createTree();
codeTree->createHuffmanArrays();
mergingTreeNode< mergingType > *rootCopy, *tmp;
rootCopy = codeTree->getRootCopy();
tmp = rootCopy;
//each time the file's buffer is empty
// these variables are hold to keep track
// of the last operation and continue it's job
int tmpj =0,tmpk=0;
bool middle = false;
cout << "Done\nDecoding file...\n0 % (0) Bytes." << flush;
//if we reach to the end of file
// the readDone variable sets to true
while(!readDone)
{
readFile(); //read 1000 bytes to file's buffer
bool done = false; //to check if we reach to one leaf or not
int i = 0,j = 0,k = 0; //counters
//go through file's buffer
for(i = 0; i < fileBufferSize2; i++, currpos++)
{
//check each bit
for(j = 0, k = 128; j < 8; j++, k /= 2)
{
//check if we continue track of the last
// character of the file's buffer
if(middle)
{ //so restore the variables
middle = false;
j = tmpj;
k = tmpk;
}
//if all bits are done and the rest is
// the zeros we filled with zero
// so break and do not continue
if( (readDone && (zeros == (9 - j))) &&
( i == (fileBufferSize2 - 1)) )
{
done = true;
break;
}
done = false;
//if current bit is 0
if( (fileBuffer2[i] & k) == 0 )
{
//if this is a leaf
if( tmp->leftPtr == NULL )
{
done = true;
//if file's buffer is full so write it to file
if(fileBufferSize == 1000)
writeTheFile();
//write character to buffer
fileBuffer[fileBufferSize++] = (tmp->data).data;
outputfilesize++;
tmp = rootCopy->leftPtr;
}
else //go to left (for zeros we go to left)
tmp = tmp->leftPtr;
}
else
{
//if this is a leaf
if( tmp->rightPtr == NULL )
{
done = true; //for leaves
//if file's buffer is full so write it to file
if(fileBufferSize == 1000)
writeTheFile();
//write character to buffer
fileBuffer[fileBufferSize++] = (tmp->data).data;
outputfilesize++;
tmp = rootCopy ->rightPtr;//go to right
}
else //go to right (for zeros we go to right)
tmp = tmp->rightPtr;
}
}
//if done one percent
if( (currpos % percent) == 0 )
{
cout << '\r' << ++curper << " % ("
<< currpos << ") Bytes.";
}
}
//we didn't write the last character
if( (zeros == 0) && readDone )
fileBuffer[fileBufferSize++] = (tmp->data).data;
if(done) //nothing to continue
{
fileBufferSize2 = 0; //reset file's buffer size
middle = false; //no need
}
else
{
if(j != 8) //if we're at the middle of character
{
//backup variables
middle = true;
tmpj = j - 1;
tmpk = k * 2;
fileBuffer2[0] = fileBuffer2[fileBufferSize2];
fileBufferSize2 = 1;
}
else //we've done all the bits
{
fileBufferSize2 = 0; //reset file's buffer size
middle = false; //no need
}
}
}
//show the 100% progress
if(fileBufferSize != 0)
writeTheFile();
cout << '\r' << "100 % ("
<< inputfilesize << ") Bytes.";
cout << "\nOutpuf file size: " << outputfilesize;
cout << "\nCompression operation completed successfully.";
//release dynamic memory
cout << "\nReleasing memory..." << flush;
delete [] fileBuffer2;
delete [] fileBuffer;
delete [] counts;
delete codeTree;
cout << "Done";
}
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