--- a/sources/huffman/huffcodec.cpp Fri May 15 20:10:44 2015 +0300
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,329 +0,0 @@
-/*
- * skulltag::HuffmanCodec class - Huffman encoder and decoder.
- *
- * Copyright 2009 Timothy Landers
- * email: code.vortexcortex@gmail.com
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-#include "huffcodec.h"
-
-/** Prevents naming convention problems via encapsulation. */
-namespace skulltag {
-
-// HuffmanCodec Implementation
-
- /** Reverses the order of bits in a byte.
- * EG: The statement <code>reverseMap[0xAF] == 0xF5</code> is <code>true</code>. <br>
- * The index <code>10101111</code> stores the reverse value: <code>11110101</code>. <br>
- * Note: One array lookup is much faster than Eight bit manipulating loop iterations. */
- unsigned char const HuffmanCodec::reverseMap[] = {
- 0,128, 64,192, 32,160, 96,224, 16,144, 80,208, 48,176,112,240,
- 8,136, 72,200, 40,168,104,232, 24,152, 88,216, 56,184,120,248,
- 4,132, 68,196, 36,164,100,228, 20,148, 84,212, 52,180,116,244,
- 12,140, 76,204, 44,172,108,236, 28,156, 92,220, 60,188,124,252,
- 2,130, 66,194, 34,162, 98,226, 18,146, 82,210, 50,178,114,242,
- 10,138, 74,202, 42,170,106,234, 26,154, 90,218, 58,186,122,250,
- 6,134, 70,198, 38,166,102,230, 22,150, 86,214, 54,182,118,246,
- 14,142, 78,206, 46,174,110,238, 30,158, 94,222, 62,190,126,254,
- 1,129, 65,193, 33,161, 97,225, 17,145, 81,209, 49,177,113,241,
- 9,137, 73,201, 41,169,105,233, 25,153, 89,217, 57,185,121,249,
- 5,133, 69,197, 37,165,101,229, 21,149, 85,213, 53,181,117,245,
- 13,141, 77,205, 45,173,109,237, 29,157, 93,221, 61,189,125,253,
- 3,131, 67,195, 35,163, 99,227, 19,147, 83,211, 51,179,115,243,
- 11,139, 75,203, 43,171,107,235, 27,155, 91,219, 59,187,123,251,
- 7,135, 71,199, 39,167,103,231, 23,151, 87,215, 55,183,119,247,
- 15,143, 79,207, 47,175,111,239, 31,159, 95,223, 63,191,127,255
- };
-
- /** Creates a new HuffmanCodec
- * @param treeData char array containing the tree data to use.
- * @param dataLength number of chars in treeData. */
- HuffmanCodec::HuffmanCodec(
- unsigned char const * const treeData,
- int dataLength
- ) : Codec() {
- init();
- // init code table (256 pointers to Huffman Leaf Nodes.)
- codeTable = new HuffmanNode*[256];
- for (int i = 0; i < 256; i++) codeTable[i] = 0;
- // build root node
- root = new HuffmanNode;
- root->bitCount = 0;
- root->code = 0;
- root->value = -1;
- // recursive Huffman tree builder.
- buildTree( root, treeData, 0, dataLength, codeTable, 256 );
- huffResourceOwner = true;
- }
-
-
- /** Creates a new HuffmanCodec that uses the specified Huffman resources.
- * @param treeRootNode The root node of a valid huffman tree.
- * @param leafCodeTable A code lookup table where references to HuffmanNodes are stored with their array index equal to their value.
- * Note: The tree nodes will not be released upon destruction of this HuffmanCodec. */
- HuffmanCodec::HuffmanCodec(
- HuffmanNode * treeRootNode,
- HuffmanNode ** leafCodeTable
- ){
- init();
- // assign values -- no table building or allocations.
- root = treeRootNode;
- codeTable = leafCodeTable;
- huffResourceOwner = false;
- }
-
- /** Checks the ownership state of this HuffmanCodec's resources.
- * @return true if the tree & code table will be released upon destruction of this HuffmanCodec. <br>
- * A false return value means this HuffmanCodec is not responsible for deleting its resources. */
- bool HuffmanCodec::huffmanResourceOwner(){
- return huffResourceOwner;
- }
-
- /** Perform initialization procedures common to all constructors. */
- void HuffmanCodec::init(){
- writer = new BitWriter();
- reverseBits = false;
- expandable = true;
- huffResourceOwner = false;
- }
-
- /** Increases a codeLength up to the longest Huffman code bit length found in the node or any of its children. <br>
- * Set to Zero before calling to determine maximum code bit length.
- * @param node in: The node to begin searching at.
- * @param codeLength out: Variable to hold the longest code bit length found. */
- void HuffmanCodec::maxCodeLength( HuffmanNode const * const node, int &codeLength ){
- // [TL] We must walk each tree node since the codeTable may not contain the set of all leaf nodes.
- // bail on NULL node (tree is corrupt).
- if ( node == 0) return;
- // Recurse across children if they exist.
- if ( node->branch != 0 ){
- maxCodeLength( &(node->branch[0]), codeLength );
- maxCodeLength( &(node->branch[1]), codeLength );
- } else if ( codeLength < node->bitCount ){
- // set codeLength if it's smaller than current node's bitCount.
- codeLength = node->bitCount;
- }
- }
-
- /** Decreases a codeLength to the shortest Huffman code bit length found in the node or any of its children. <br>
- * Set to Zero before calling to determine minimum code bit length.
- * @param node in: The node to begin searching at.
- * @param codeLength out: Variable to hold the longest code bit length found. */
- void HuffmanCodec::minCodeLength( HuffmanNode const * const node, int &codeLength ){
- /* [TL] Do not optimize under the assumption child nodes will have longer code Lengths!
- * Future subclasses may have trees that diverge from Huffman specs. */
- // bail on NULL node (tree is corrupt).
- if ( node == 0 ) return;
- // Recurse across children if they exist.
- if ( node->branch != 0 ){
- minCodeLength( &(node->branch[0]), codeLength );
- minCodeLength( &(node->branch[1]), codeLength );
- } else if ( (codeLength > node->bitCount) || (codeLength == 0) ) {
- // set codeLength if it's Zero or larger than current node's bitCount.
- codeLength = node->bitCount;
- }
- }
-
- /** Recursively builds a Huffman Tree. <br>
- * The initial root node should have the following field values: <br>
- * <pre>
- * bitCount : 0
- * code : 0
- * value : -1
- * branch : 0 (NULL)
- * </pre>
- * @param node in/out: branch node of the Huffman Tree.
- * @param treeData in: char array containing the Huffman Tree's byte representation.
- * @param index in: Current array element to read the next tree node from.
- * @param dataLength in: Length of treeData
- * @param codeTable in/out: array of pointers to HuffmanNode structs.
- * @param tableLength in: maximum index allowed in the codeTable.
- * @return the next index to read from or -1 if an error occurs.
- * */
- int HuffmanCodec::buildTree(
- HuffmanNode * node,
- unsigned char const * const treeData,
- int index,
- int dataLength,
- HuffmanNode ** const &codeTable,
- int tableLength
- ){
- if ( index >= dataLength ) return -1;
- // Read the branch description bit field
- int desc = treeData[index];
- index++;
-
- // Create the array that will hold L/R child nodes of this branch.
- node->branch = new HuffmanNode[2];
-
- // Read the child Nodes for this branch.
- for ( int i = 0; i < 2; i++ ){
- // Increase bit count, and update huffman code to match the node's tree position.
- node->branch[i].bitCount = node->bitCount + 1;
- node->branch[i].code = (node->code << 1) | i; // appends a 0 or 1 depending on L/R branch.
- node->branch[i].value = -1; // default value.
-
- // Test a bit from the branch description (least significant bit == left)
- if ( (desc & (1 << i)) == 0 ){
- // Child node is a branch; Recurse.
- if ( (index = buildTree( &(node->branch[i]), treeData, index, dataLength, codeTable, tableLength )) < 0 ) return -1;
- // This means the entire left sub tree will be read before the right sub tree gets read.
- } else {
- // Read leaf value and map its value/index in the nodes array.
- if ( index >= dataLength ) return -1;
- // set the nodes huffman code values.
- node->branch[i].code = (node->code << 1) | i;
- node->branch[i].bitCount = node->bitCount+1;
- node->branch[i].value = treeData[index] & 0xff;
- // NULL the child node's branch to mark it as a leaf.
- node->branch[i].branch = 0;
- // buffer overflow check.
- if ( (node->branch[i].value >= 0) && (node->branch[i].value <= tableLength ) )
- // store a pointer to the leaf node into the code table at the location of its byte value.
- codeTable[ node->branch[i].value ] = &node->branch[i];
- index++;
- }
- }
-
- return index;
- }
-
- /** Decodes data read from an input buffer and stores the result in the output buffer.
- * @return number of bytes stored in the output buffer or -1 if an error occurs while encoding. */
- int HuffmanCodec::encode(
- unsigned char const * const input, /**< in: pointer to the first byte to encode. */
- unsigned char * const output, /**< out: pointer to an output buffer to store data. */
- int const &inLength, /**< in: number of bytes of input buffer to encoded. */
- int const &outLength /**< in: maximum length of data to output. */
- ) const {
- // setup the bit buffer to output. if not expandable Limit output to input length.
- if ( expandable ) writer->outputBuffer( output, outLength );
- else writer->outputBuffer( output, ((inLength + 1) < outLength) ? inLength + 1 : outLength );
-
- writer->put( (unsigned char)0 ); // reserve place for padding signal.
-
- HuffmanNode * node; // temp ptr cache;
- for ( int i = 0; i < inLength; i++ ){
- node = codeTable[ 0xff & input[i] ]; //lookup node
- // Put the huffman code into the bit buffer and bail if error occurs.
- if ( !writer->put( node->code, node->bitCount ) ) return -1;
- }
- int bytesWritten, padding;
- if ( writer->finish( bytesWritten, padding ) ){
- // write padding signal byte to begining of stream.
- output[0] = (unsigned char)padding;
- } else return -1;
-
- // Reverse the bit order of each byte (Old Huffman Compatibility Mode)
- if ( reverseBits ) for ( int i = 1; i < bytesWritten; i++ ){
- output[i] = reverseMap[ 0xff & output[i] ];
- }
-
- return bytesWritten;
- } // end function encode
-
- /** Decodes data read from an input buffer and stores the result in the output buffer.
- * @return number of bytes stored in the output buffer or -1 if an error occurs while decoding. */
- int HuffmanCodec::decode(
- unsigned char const * const input, /**< in: pointer to data that needs decoding. */
- unsigned char * const output, /**< out: pointer to output buffer to store decoded data. */
- int const &inLength, /**< in: number of bytes of input buffer to read. */
- int const &outLength /**< in: maximum length of data to output. */
- ){
- if ( inLength < 1 ) return 0;
- int bitsAvailable = ((inLength-1) << 3) - (0xff & input[0]);
- int rIndex = 1; // read index of input buffer.
- int wIndex = 0; // write index of output buffer.
- char byte = 0; // bits of the current byte.
- int bitsLeft = 0; // bits left in byte;
-
- HuffmanNode * node = root;
-
- // Traverse the tree, output values.
- while ( (bitsAvailable > 0) && (node != 0) ){
-
- // Get the next byte if we've run out.
- if ( bitsLeft <= 0 ){
- byte = input[rIndex++];
- if ( reverseBits ) byte = reverseMap[ 0xff & byte ];
- bitsLeft = 8;
- }
-
- // Traverse the tree according to the most significant bit.
- node = &(node->branch[ ((byte >> 7) & 0x01) ]);
-
- // Is the node Non NULL, and a leaf?
- if ( (node != 0) && (node->branch == 0) ){
- // buffer overflow prevention
- if ( wIndex >= outLength ) return wIndex;
- // Output leaf node's value and restart traversal at root node.
- output[ wIndex++ ] = (unsigned char)(node->value & 0xff);
- node = root;
- }
-
- byte <<= 1; // cue up the next bit
- bitsLeft--; // use up one bit of byte
- bitsAvailable--; // decrement total bits left
- }
-
- return wIndex;
- } // end function decode
-
- /** Deletes all sub nodes of a HuffmanNode by traversing and deleting its child nodes.
- * @param treeNode pointer to a HuffmanNode whos children will be deleted. */
- void HuffmanCodec::deleteTree( HuffmanNode * treeNode ){
- if ( treeNode == 0 ) return;
- if ( treeNode->branch != 0 ){
- deleteTree( &(treeNode->branch[0]) );
- deleteTree( &(treeNode->branch[1]) );
- delete treeNode->branch;
- }
- }
-
- /** Destructor - frees resources. */
- HuffmanCodec::~HuffmanCodec() {
- delete writer;
- //check for resource ownership before deletion
- if ( huffmanResourceOwner() ){
- delete codeTable;
- deleteTree( root );
- delete root;
- }
- }
-
- /** Enables or Disables backwards bit ordering of bytes.
- * @param backwards "true" enables reversed bit order bytes, "false" uses standard byte bit ordering. */
- void HuffmanCodec::reversedBytes( bool backwards ){ reverseBits = backwards; }
-
- /** Check the state of backwards bit ordering for bytes.
- * @return true: bits within bytes are reversed. false: bits within bytes are normal. */
- bool HuffmanCodec::reversedBytes(){ return reverseBits; }
-
- /** Enable or Disable data expansion during encoding.
- * @param expandingAllowed "true" allows encoding to expand data. "false" causes failure upon expansion. */
- void HuffmanCodec::allowExpansion( bool expandingAllowed ){ expandable = expandingAllowed; }
-
- /** Check the state of data expandability.
- * @return true: data expansion is allowed. false: data is not allowed to expand. */
- bool HuffmanCodec::allowExpansion(){ return expandable; }
-
-
-}; // end namespace skulltag