/* Function: decodeFileToFile
* --------------------------
* Main cyphered text decoding process.
*/
void decodeFileToFile(ibstream& infileStream, Node* root, obstream& outfileStream) {
int bit;
Node* currentNode = root;
/* Runs through every cypher bit and, at the same time, move
* through tree to symbols leafs */
while ((bit = infileStream.readBit()) > -1) {
if (bit == 0) {
currentNode = currentNode->leftChild;
}else{
currentNode = currentNode->rightChild;
}
if ((currentNode->symbol) < NOT_A_CHAR) {
if (((char)currentNode->symbol) == EOF) {
break;
}else{
outfileStream.put((char)(currentNode->symbol));
}
currentNode = root;
}
}
}
/* Function: readFileHeader
* Reads header of cyphered file and reconstructs huffman tree
* --------------------------------------------------------
* Reads header of cyphered file and reconstructs huffman tree
* for this cypher file
*/
void readFileHeader(ibstream& infileStream, Node* root) {
/* Recursive header decoding */
int bit = 0;
if ((bit = infileStream.readBit()) > -1) {
if (bit == 1) {//It's a tree leaf
/* We write followed symbol into leaf node */
ext_char nodeSymb = infileStream.get();
root->symbol = nodeSymb;
}else if (bit == 0) {//It's a tree knot
/* We have to create children for it */
root->symbol = NOT_A_CHAR;
Node* leftChild = new Node;
Node* rightChild = new Node;
root->leftChild = leftChild;
root->rightChild = rightChild;
/* Move to children */
readFileHeader(infileStream, leftChild);
readFileHeader(infileStream, rightChild);
}
}
}
