diff -r 5f8a03274d75 -r 6de6d9a64ebd huffman/bitreader.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/huffman/bitreader.cpp	Fri May 15 20:13:36 2015 +0300
@@ -0,0 +1,144 @@
+/*
+ * skulltag::BitReader class - Allows reading arbitrary bit lengths of data.
+ * Version 1 - Revsion 0
+ *
+ * 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 "bitreader.h"
+/** Prevents naming convention problems via encapsulation. */
+namespace skulltag {
+	// BitReader class implementation
+	
+	int BitReader::intBitSize = 0;
+	int BitReader::intSize = 0;
+	int BitReader::mask[32] = {0};
+
+	/** Creates a new BitReader. */
+	BitReader::BitReader(){
+		init();
+	}
+	
+	/** Creates a new BitReader.
+	 * @param input		Source of data that bits will be read from.
+	 * @param max		Maximum number of chars to read. */
+	BitReader::BitReader( unsigned char const * input, int const &max ){
+		inputBuffer( input, max );
+	}
+		
+	/** Sets the input buffer that bytes will be read from.
+	 * @param input		Source of data that bits will be read from.
+	 * @param max		Maximum number of chars to input.
+	 * @return true if successful, false if an error occurs. */
+	bool BitReader::inputBuffer( unsigned char const * input, int const &max ){
+		init(); // zero the vars.
+		currentByte = input;
+		if ( input == 0 ) return false;
+		if ( max < 1 ) return false;
+		bytesAvailable = max;
+		bitsAvailable = max << 3;
+		maximumBytes = max;
+		return true;
+	}
+
+	/** Initializes this BitReader */
+	void BitReader::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;
+			
+			intBitSize = intSize << 3;
+		}
+
+		// initialize member variables.
+		bitsAvailable =		0;
+		bytesAvailable =	0;
+		bufferBits =		0;
+		currentByte =		0;
+		maximumBytes =		0;
+		bitsUsed =			0;
+	}
+	
+	/** Fills the internal bit buffer.
+	 * @return true if successful, false if an error occurs. */
+	bool BitReader::fill(){
+		if ( (currentByte == 0) || (bytesAvailable <= 0) ) return false;
+
+		// while there's at least one octet free in the buffer, and one byte to read.
+		while ( (bitsUsed < (intBitSize - 8)) && (bytesAvailable > 0) ){
+
+			// put a byte into the bottom end of the buffer.
+			bufferBits |= (*currentByte & mask[8]) << (intBitSize - bitsUsed - 8);
+
+			// Set variables to reflect the change.
+			currentByte++;
+			bytesAvailable--;
+			bitsUsed += 8;
+		}
+		return true;
+	}
+	
+	/** Fetches a specified number of bits and stores them in an int.
+	 * @param bits 		destination of the retrieved bits. <br>
+	 *		The bits will be stored in the least significant portion of the int.
+	 * @param count		the number of bits to fetch.
+	 * @return the number of bits read -- may not be equal to the amount requested. */
+	int BitReader::get( int &bits, int const &count ){
+		bits = 0;
+		// Requesting more bits than are available.
+		if ( count > bitsAvailable ) return 0;
+		if ( (count > bitsUsed) && (!fill()) ) return 0;
+		bits = (bufferBits >> (intBitSize - count)) & mask[count];
+		// lesser of bits in buffer or requested bits.
+		int got = (bitsUsed < count) ? bitsUsed : count;
+		// get as many bits from the buffer as we can.
+		if ( got > 0 ){
+			bufferBits <<= got;
+			bitsUsed -= got;
+			bitsAvailable -= got;
+		}
+		// if more bits are requested.
+		if ( count > got ){
+			if (!fill()) {
+				bits = (bits >> (count - got)) & mask[count - got];
+				return got;
+			}
+			got = count - got;
+			// avoid reading more bits than available.
+			if ( got <= bitsAvailable ){
+				bits |= (bufferBits >> (intBitSize - got)) & mask[got];
+				bufferBits <<= got;
+				bitsUsed -= got;
+				bitsAvailable -= got;
+			}
+		}
+		return count;
+	}
+	
+	/** @return Amount of bits that can be read from this BitReader. */
+	int BitReader::availableBits(){ return bitsAvailable; }
+	
+} // end namespace skulltag