--- a/sources/huffman/bitwriter.cpp Fri May 15 20:10:44 2015 +0300
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,271 +0,0 @@
-/*
- * skulltag::BitWriter class - Enables writing arbitrary bit lengths of data.
- *
- * 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 "bitwriter.h"
-
-/* The internal buffer of bits is an int which is initiallized to zero.
- * The Bit Buffer: [00000000000000000000000000000000] - 0 bits stored.
- *
- * Bits stored in the bit buffer occupy the most significant bits available.
- * When bits are stored their order is preserved.
- * Storing the 5 bits 01011 into the bit buffer would result in:
- * The Bit Buffer: [01011000000000000000000000000000] - 5 bits stored.
- *
- * Additionally storing 0x12f3 (13 bits) would result in:
- * The Bit Buffer: [01011100101111001100000000000000] - 18 bits stored.
- *
- * Data is stored via any of the put(...) functions.
- *
- * To retrieve bytes (chars) of data from the bit buffer and empty the bit buffer: flush();
- * Flushing the bit buffer takes groups of 8 bits (octets) and stores them in the
- * output buffer at the current byte position. Calling flush() would cause output
- * to receive 2 bytes (0x5c, 0xbc) == (01011100, 10111100) and the remaining bits would
- * be moved to the most significant bit positions.
- * The Bit Buffer: [11000000000000000000000000000000] - 2 bits stored.
- * Note: The empty bits of the bit buffer must be zero to avoid additional masking operations.
- * flush() is called automatically if the bit buffer is too full during a call to put(...)
- *
- * When the bit storage operation is complete call finish(...). Finish will flush as many full
- * bytes of data into the output buffer as possible, the remaining bits will be padded out
- * to a full octet with zeros (on their less significant side), then written to the output
- * buffer. finish( bytesStored, padding ) passes by reference the number of bytes stored
- * and number of padding bits added (0 to 7) to the last stored byte.
- *
- * Bits are not added one at a time, they are masked, shifted and bitwise OR'ed into
- * the buffer in as large a group as possible. This allows the BitWriter to add multiple bits in a single
- * operation instead of calling a function for each 1 bit added.
- *
- * Normal usage:
- *
- * char * dataArray = new char[ max_output_size ];
- * BitWriter * buffer = new BitWriter( dataArray, max_output_size );
- * ...
- * // various calls to put(...);
- * ...
- * int numBytesOutput, paddedBits;
- * buffer->finish( numBytesOutput, paddedBits );
- * ...
- * // do something with dataArray
- * ...
- * delete buffer;
- * delete dataArray;
- *
- * */
-
-/** Prevents naming convention problems via encapsulation. */
-namespace skulltag {
-
- // Static variable initially set to zero as a signal for init()
- int BitWriter::intSize = 0;
- int BitWriter::mask[32];
-
- /** Initializes this BitWriter. */
- void BitWriter::init(){
-
- // initialize static variables if not initialized yet.
- if ( intSize == 0 ){
- intSize = sizeof maximumBytes;
- mask[0] = 0;
-
- // fill mask such that m = { 0, 1, 3, 7, 15, etc. }
- for ( int i = 1; i < 32; i++ ) mask[i] = (mask[i-1] << 1) | 1;
- }
-
- // initialize member variables.
- bitsAvailable = 0;
- bytesAvailable = 0;
- bufferBits = 0;
- currentByte = 0;
- maximumBytes = 0;
- bitsLeft = intSize << 3;
- }
-
- /** Creates a new BitWriter. */
- BitWriter::BitWriter(){
- init();
- }
-
- /** Creates a new BitWriter.
- * @param output Destination that bits will be written to.
- * @param max Maximum number of chars to output. */
- BitWriter::BitWriter( unsigned char * const output, int const &max ){
- outputBuffer( output, max );
- }
-
- /** Sets the output buffer that bytes will be written to.
- * @param output Destination that bits will be written to.
- * @param max Maximum number of chars to output.
- * @return true if successful, false otherwise. */
- bool BitWriter::outputBuffer( unsigned char * const output, int const &max ){
- init(); // zero the vars.
- currentByte = output;
- if ( output == 0 ) return false;
- if ( max < 1 ) return false;
- bytesAvailable = max;
- bitsAvailable = max << 3;
- maximumBytes = max;
- return true;
- }
-
- /** Appends a char worth of bits to the buffer.
- * @param bits the bits to append.
- * @return true if successful, false otherwise. */
- bool BitWriter::put( unsigned char const &bits ){
- return put( (int)bits, 8 );
- }
-
- /** Appends a short worth of bits to the buffer.
- * @param bits the bits to append.
- * @return true if successful, false otherwise. */
- bool BitWriter::put( short const &bits ){
- static int shortBitSize = (sizeof bits) << 3;
- return put( (int)bits, shortBitSize );
- }
- /** Appends an int worth of bits to the buffer.
- * @param bits the bits to append.
- * @return true if successful, false otherwise. */
- bool BitWriter::put( int const &bits ){
- static int intBitSize = intSize << 3;
- return put( bits, intBitSize);
- }
-
- /** Appends multiple chars from a buffer to this BitWriter.
- * @param inputBuffer pointer to char data
- * @param count number of chars to read
- * @return true if successful, false otherwise. */
- bool BitWriter::put( unsigned char const * const inputBuffer, int count ){
- int i = 0;
-
- // Read in 4 bytes at a time and send all at once to the bit buffer.
- while ( (i + 3) < count ){
- if ( !put(
- ((int)inputBuffer[ i ] << 24) |
- ((int)inputBuffer[i+1] << 16) |
- ((int)inputBuffer[i+2] << 8) |
- (int)inputBuffer[i+3], 32
- ) ) return false;
- i+=4;
- }
-
- // If any bytes remain, output them one at a time.
- while ( i < count ){
- if ( !put( (int)inputBuffer[ i ], 8 ) ) return false;
- i++;
- }
-
- return true;
- }
-
- /** Appends a specified number of bits from an int to the buffer.
- * @param bits the bits to append. <br>
- * The bits should be stored in the least significant portion of the int.
- * @param count the number of bits to append.
- * @return true if successful, false otherwise. */
- bool BitWriter::put( int const &bits, int count ){
- if ( count > bitsAvailable ) return false;
- if ( (bitsLeft < 1) && (!flush()) ) return false;
- if ( count > bitsLeft ){
- // not enough space in buffer, fill buffer with top end of input bits then flush.
- bufferBits |= mask[bitsLeft] & (bits >> (count - bitsLeft));
- count -= bitsLeft;
- bitsAvailable -= bitsLeft;
- bitsLeft = 0;
-
- // Buffer's full, needs flushing.
- if (!flush()) return false;
- }
-
- // if there are still bits of input...
- if ( count > 0 ){
-
- // shift the input bits up to the end of the bit buffer.
- bufferBits |= (mask[count] & bits) << (bitsLeft - count);
- bitsAvailable -= count;
- bitsLeft -= count;
- }
- return true;
- }
-
- /** Writes any full chars of data stored in this BitWriter to the output char buffer.
- * @return true if successful, false if an error occurs. */
- bool BitWriter::flush(){
- // static var to hold how many bits are in an int.
- static int intBitSize = intSize << 3;
- if ( currentByte == 0 ) return false;
- int numBits = intBitSize - bitsLeft;
-
- // while there's at least one octet of data in the buffer.
- while ( numBits > 7 ){
-
- // fail if no bytes can be written.
- if ( bytesAvailable <= 0 ) return false;
-
- // get a byte off the top end of the buffer.
- *currentByte = (bufferBits >> (intBitSize - 8)) & mask[8];
-
- // Set variables to reflect the change.
- currentByte++;
- bytesAvailable--;
- bufferBits = bufferBits << 8;
- bitsLeft += 8;
- numBits -= 8;
- }
- return true;
- }
-
- /** Flushes this BitWriter then outputs any partial chars by padding them with zeros. <br>
- * After calling finish() all other calls to update the BitWriter will fail until a buffer is set via outputBuffer().
- * @param bytesWritten out: the number of bytes written to the output buffer.
- * @param paddingBits out: the number of padding bits used in the final byte of output.
- * @return true if successful, false if an error occurs. */
- bool BitWriter::finish( int &bytesWritten, int &paddingBits ){
- static int intBitSize = intSize << 3;
- // set meaningful return values even if flush() fails.
- bytesWritten = maximumBytes - bytesAvailable;
- paddingBits = 0;
- if ( flush() ){
- // use a temp var to avoid setting paddingBits to invalid value on failure.
- int pad = (8 - (intBitSize - bitsLeft)) & 7;
- if ( pad > 0 ){
- // all empty bits should be zero. Artificially extend by the number of bits needed.
- bitsLeft -= pad;
- if ( !flush() ){
- // Prevent futher use even on failure.
- init();
- return false;
- }
- // return the temp bit padding value.
- paddingBits = pad;
- }
- bytesWritten = maximumBytes - bytesAvailable;
- init(); // set initial state -- no further writing can occur.
- return true;
- }
- // Prevents futher use even on failure.
- init();
- return false;
- }
-
-}