code: package edu.gmu.swe.kp.listener;
  /*
   * Copyright (C) 2010 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  import java.io.UnsupportedEncodingException;
  
  /**
   * Utilities for encoding and decoding the Base64 representation of
   * binary data.  See RFCs <a
   * href="http://www.ietf.org/rfc/rfc2045.txt">2045</a> and <a
   * href="http://www.ietf.org/rfc/rfc3548.txt">3548</a>.
   */
  public class Base64 {
  	/**
  	 * Default values for encoder/decoder flags.
  	 */
  	public static final int DEFAULT = 0;
  
  	/**
  	 * Encoder flag bit to omit the padding '=' characters at the end
  	 * of the output (if any).
  	 */
  	public static final int NO_PADDING = 1;
  
  	/**
  	 * Encoder flag bit to omit all line terminators (i.e., the output
  	 * will be on one long line).
  	 */
  	public static final int NO_WRAP = 2;
  
  	/**
  	 * Encoder flag bit to indicate lines should be terminated with a
  	 * CRLF pair instead of just an LF.  Has no effect if {@code
  	 * NO_WRAP} is specified as well.
  	 */
  	public static final int CRLF = 4;
  
  	/**
  	 * Encoder/decoder flag bit to indicate using the "URL and
  	 * filename safe" variant of Base64 (see RFC 3548 section 4) where
  	 * {@code -} and {@code _} are used in place of {@code +} and
  	 * {@code /}.
  	 */
  	public static final int URL_SAFE = 8;
  
  	/**
  	 * Flag to pass to Base64OutputStream to indicate that it
  	 * should not close the output stream it is wrapping when it
  	 * itself is closed.
  	 */
  	public static final int NO_CLOSE = 16;
  
  	//  --------------------------------------------------------
  	//  shared code
  	//  --------------------------------------------------------
  
  	/* package */ static abstract class Coder {
  		public byte[] output;
  		public int op;
  
  		/**
  		 * Encode/decode another block of input data.  this.output is
  		 * provided by the caller, and must be big enough to hold all
  		 * the coded data.  On exit, this.opwill be set to the length
  		 * of the coded data.
  		 *
  		 * @param finish true if this is the final call to process for
  		 *        this object.  Will finalize the coder state and
  		 *        include any final bytes in the output.
  		 *
  		 * @return true if the input so far is good; false if some
  		 *         error has been detected in the input stream..
  		 */
  		public abstract boolean process(byte[] input, int offset, int len, boolean finish);
  
  		/**
  		 * @return the maximum number of bytes a call to process()
  		 * could produce for the given number of input bytes.  This may
  		 * be an overestimate.
  		 */
  		public abstract int maxOutputSize(int len);
  	}
  
  	//  --------------------------------------------------------
  	//  decoding
  	//  --------------------------------------------------------
  
  	/**
  	 * Decode the Base64-encoded data in input and return the data in
  	 * a new byte array.
  	 *
  	 * <p>The padding '=' characters at the end are considered optional, but
  	 * if any are present, there must be the correct number of them.
  	 *
  	 * @param str    the input String to decode, which is converted to
  	 *               bytes using the default charset
  	 * @param flags  controls certain features of the decoded output.
  	 *               Pass {@code DEFAULT} to decode standard Base64.
  	 *
  	 * @return byte[]
  	 * @throws IllegalArgumentException if the input contains
  	 * incorrect padding
  	 */
  	public static byte[] decode(String str, int flags) {
  		return decode(str.getBytes(), flags);
  	}
  
  	/**
  	 * Decode the Base64-encoded data in input and return the data in
  	 * a new byte array.
  	 *
  	 * <p>The padding '=' characters at the end are considered optional, but
  	 * if any are present, there must be the correct number of them.
  	 *
  	 * @param input the input array to decode
  	 * @param flags  controls certain features of the decoded output.
  	 *               Pass {@code DEFAULT} to decode standard Base64.
  	 *
  	 * @return byte[]
  	 * @throws IllegalArgumentException if the input contains
  	 * incorrect padding
  	 */
  	public static byte[] decode(byte[] input, int flags) {
  		return decode(input, 0, input.length, flags);
  	}
  
  	/**
  	 * Decode the Base64-encoded data in input and return the data in
  	 * a new byte array.
  	 *
  	 * <p>The padding '=' characters at the end are considered optional, but
  	 * if any are present, there must be the correct number of them.
  	 *
  	 * @param input  the data to decode
  	 * @param offset the position within the input array at which to start
  	 * @param len    the number of bytes of input to decode
  	 * @param flags  controls certain features of the decoded output.
  	 *               Pass {@code DEFAULT} to decode standard Base64.
  	 * @return byte[]
  	 *
  	 * @throws IllegalArgumentException if the input contains
  	 * incorrect padding
  	 */
  	public static byte[] decode(byte[] input, int offset, int len, int flags) {
  		// Allocate space for the most data the input could represent.
  		// (It could contain less if it contains whitespace, etc.)
  		Decoder decoder = new Decoder(flags, new byte[len*3/4]);
  
  		if (!decoder.process(input, offset, len, true)) {
  			throw new IllegalArgumentException("bad base-64");
  		}
  
  		// Maybe we got lucky and allocated exactly enough output space.
  		if (decoder.op == decoder.output.length) {
  			return decoder.output;
  		}
  
  		// Need to shorten the array, so allocate a new one of the
  		// right size and copy.
  		byte[] temp = new byte[decoder.op];
  		System.arraycopy(decoder.output, 0, temp, 0, decoder.op);
  		return temp;
  	}
  
  	/* package */ static class Decoder extends Coder {
  		/**
  		 * Lookup table for turning bytes into their position in the
  		 * Base64 alphabet.
  		 */
  		private static final int DECODE[] = {
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
  				52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
  				-1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
  				15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
  				-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  				41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  		};
  
  		/**
  		 * Decode lookup table for the "web safe" variant (RFC 3548
  		 * sec. 4) where - and _ replace + and /.
  		 */
  		private static final int DECODE_WEBSAFE[] = {
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,
  				52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
  				-1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
  				15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63,
  				-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  				41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  				-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  		};
  
  		/** Non-data values in the DECODE arrays. */
  		private static final int SKIP = -1;
  		private static final int EQUALS = -2;
  
  		/**
  		 * States 0-3 are reading through the next input tuple.
  		 * State 4 is having read one '=' and expecting exactly
  		 * one more.
  		 * State 5 is expecting no more data or padding characters
  		 * in the input.
  		 * State 6 is the error state; an error has been detected
  		 * in the input and no future input can "fix" it.
  		 */
  		private int state;   // state number (0 to 6)
  		private int value;
  
  		final private int[] alphabet;
  
  		public Decoder(int flags, byte[] output) {
  			this.output = output;
  
  			alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE;
  			state = 0;
  			value = 0;
  		}
  
  		/**
  		 * @return an overestimate for the number of bytes {@code
  		 * len} bytes could decode to.
  		 */
  		public int maxOutputSize(int len) {
  			return len * 3/4 + 10;
  		}
  
  		/**
  		 * Decode another block of input data.
  		 *
  		 * @return true if the state machine is still healthy.  false if
  		 *         bad base-64 data has been detected in the input stream.
  		 */
  		public boolean process(byte[] input, int offset, int len, boolean finish) {
  			if (this.state == 6) return false;
  
  			int p = offset;
  			len += offset;
  
  			// Using local variables makes the decoder about 12%
  			// faster than if we manipulate the member variables in
  			// the loop.  (Even alphabet makes a measurable
  			// difference, which is somewhat surprising to me since
  			// the member variable is final.)
  			int state = this.state;
  			int value = this.value;
  			int op = 0;
  			final byte[] output = this.output;
  			final int[] alphabet = this.alphabet;
  
  			while (p < len) {
  				// Try the fast path:  we're starting a new tuple and the
  				// next four bytes of the input stream are all data
  				// bytes.  This corresponds to going through states
  				// 0-1-2-3-0.  We expect to use this method for most of
  				// the data.
  				//
  				// If any of the next four bytes of input are non-data
  				// (whitespace, etc.), value will end up negative.  (All
  				// the non-data values in decode are small negative
  				// numbers, so shifting any of them up and or'ing them
  				// together will result in a value with its top bit set.)
  				//
  				// You can remove this whole block and the output should
  				// be the same, just slower.
  				if (state == 0) {
  					while (p+4 <= len &&
  							(value = ((alphabet[input[p] & 0xff] << 18) |
  									(alphabet[input[p+1] & 0xff] << 12) |
  									(alphabet[input[p+2] & 0xff] << 6) |
  									(alphabet[input[p+3] & 0xff]))) >= 0) {
  						output[op+2] = (byte) value;
  						output[op+1] = (byte) (value >> 8);
  						output[op] = (byte) (value >> 16);
  						op += 3;
  						p += 4;
  					}
  					if (p >= len) break;
  				}
  
  				// The fast path isn't available -- either we've read a
  				// partial tuple, or the next four input bytes aren't all
  				// data, or whatever.  Fall back to the slower state
  				// machine implementation.
  
  				int d = alphabet[input[p++] & 0xff];
  
  				switch (state) {
  					case 0:
  						if (d >= 0) {
  							value = d;
  							++state;
  						} else if (d != SKIP) {
  							this.state = 6;
  							return false;
  						}
  						break;
  
  					case 1:
  						if (d >= 0) {
  							value = (value << 6) | d;
  							++state;
  						} else if (d != SKIP) {
  							this.state = 6;
  							return false;
  						}
  						break;
  
  					case 2:
  						if (d >= 0) {
  							value = (value << 6) | d;
  							++state;
  						} else if (d == EQUALS) {
  							// Emit the last (partial) output tuple;
  							// expect exactly one more padding character.
  							output[op++] = (byte) (value >> 4);
  							state = 4;
  						} else if (d != SKIP) {
  							this.state = 6;
  							return false;
  						}
  						break;
  
  					case 3:
  						if (d >= 0) {
  							// Emit the output triple and return to state 0.
  							value = (value << 6) | d;
  							output[op+2] = (byte) value;
  							output[op+1] = (byte) (value >> 8);
  							output[op] = (byte) (value >> 16);
  							op += 3;
  							state = 0;
  						} else if (d == EQUALS) {
  							// Emit the last (partial) output tuple;
  							// expect no further data or padding characters.
  							output[op+1] = (byte) (value >> 2);
  							output[op] = (byte) (value >> 10);
  							op += 2;
  							state = 5;
  						} else if (d != SKIP) {
  							this.state = 6;
  							return false;
  						}
  						break;
  
  					case 4:
  						if (d == EQUALS) {
  							++state;
  						} else if (d != SKIP) {
  							this.state = 6;
  							return false;
  						}
  						break;
  
  					case 5:
  						if (d != SKIP) {
  							this.state = 6;
  							return false;
  						}
  						break;
  				}
  			}
  
  			if (!finish) {
  				// We're out of input, but a future call could provide
  				// more.
  				this.state = state;
  				this.value = value;
  				this.op = op;
  				return true;
  			}
  
  			// Done reading input.  Now figure out where we are left in
  			// the state machine and finish up.
  
  			switch (state) {
  				case 0:
  					// Output length is a multiple of three.  Fine.
  					break;
  				case 1:
  					// Read one extra input byte, which isn't enough to
  					// make another output byte.  Illegal.
  					this.state = 6;
  					return false;
  				case 2:
  					// Read two extra input bytes, enough to emit 1 more
  					// output byte.  Fine.
  					output[op++] = (byte) (value >> 4);
  					break;
  				case 3:
  					// Read three extra input bytes, enough to emit 2 more
  					// output bytes.  Fine.
  					output[op++] = (byte) (value >> 10);
  					output[op++] = (byte) (value >> 2);
  					break;
  				case 4:
  					// Read one padding '=' when we expected 2.  Illegal.
  					this.state = 6;
  					return false;
  				case 5:
  					// Read all the padding '='s we expected and no more.
  					// Fine.
  					break;
  			}
  
  			this.state = state;
  			this.op = op;
  			return true;
  		}
  	}
  
  	//  --------------------------------------------------------
  	//  encoding
  	//  --------------------------------------------------------
  
  	/**
  	 * Base64-encode the given data and return a newly allocated
  	 * String with the result.
  	 *
  	 * @param input  the data to encode
  	 * @param flags  controls certain features of the encoded output.
  	 *               Passing {@code DEFAULT} results in output that
  	 *               adheres to RFC 2045.
  	 * @return String
  	 */
  	public static String encodeToString(byte[] input, int flags) {
  		try {
  			return new String(encode(input, flags), "US-ASCII");
  		} catch (UnsupportedEncodingException e) {
  			// US-ASCII is guaranteed to be available.
  			throw new AssertionError(e);
  		}
  	}
  
  	/**
  	 * Base64-encode the given data and return a newly allocated
  	 * String with the result.
  	 *
  	 * @param input  the data to encode
  	 * @param offset the position within the input array at which to
  	 *               start
  	 * @param len    the number of bytes of input to encode
  	 * @param flags  controls certain features of the encoded output.
  	 *               Passing {@code DEFAULT} results in output that
  	 *               adheres to RFC 2045.
  	 * @return String
  	 */
  	public static String encodeToString(byte[] input, int offset, int len, int flags) {
  		try {
  			return new String(encode(input, offset, len, flags), "US-ASCII");
  		} catch (UnsupportedEncodingException e) {
  			// US-ASCII is guaranteed to be available.
  			throw new AssertionError(e);
  		}
  	}
  
  	/**
  	 * Base64-encode the given data and return a newly allocated
  	 * byte[] with the result.
  	 *
  	 * @param input  the data to encode
  	 * @param flags  controls certain features of the encoded output.
  	 *               Passing {@code DEFAULT} results in output that
  	 *               adheres to RFC 2045.
  	 * @return byte[]
  	 */
  	public static byte[] encode(byte[] input, int flags) {
  		return encode(input, 0, input.length, flags);
  	}
  
  	/**
  	 * Base64-encode the given data and return a newly allocated
  	 * byte[] with the result.
  	 *
  	 * @param input  the data to encode
  	 * @param offset the position within the input array at which to
  	 *               start
  	 * @param len    the number of bytes of input to encode
  	 * @param flags  controls certain features of the encoded output.
  	 *               Passing {@code DEFAULT} results in output that
  	 *               adheres to RFC 2045.
  	 * @return byte[]
  	 */
  	public static byte[] encode(byte[] input, int offset, int len, int flags) {
  		Encoder encoder = new Encoder(flags, null);
  
  		// Compute the exact length of the array we will produce.
  		int output_len = len / 3 * 4;
  
  		// Account for the tail of the data and the padding bytes, if any.
  		if (encoder.do_padding) {
  			if (len % 3 > 0) {
  				output_len += 4;
  			}
  		} else {
  			switch (len % 3) {
  				case 0: break;
  				case 1: output_len += 2; break;
  				case 2: output_len += 3; break;
  			}
  		}
  
  		// Account for the newlines, if any.
  		if (encoder.do_newline && len > 0) {
  			output_len += (((len-1) / (3 * Encoder.LINE_GROUPS)) + 1) *
  					(encoder.do_cr ? 2 : 1);
  		}
  
  		encoder.output = new byte[output_len];
  		encoder.process(input, offset, len, true);
  
  		assert encoder.op == output_len;
  
  		return encoder.output;
  	}
  
  	/* package */ static class Encoder extends Coder {
  		/**
  		 * Emit a new line every this many output tuples.  Corresponds to
  		 * a 76-character line length (the maximum allowable according to
  		 * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>).
  		 */
  		public static final int LINE_GROUPS = 19;
  
  		/**
  		 * Lookup table for turning Base64 alphabet positions (6 bits)
  		 * into output bytes.
  		 */
  		private static final byte ENCODE[] = {
  				'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
  				'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
  				'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
  				'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
  		};
  
  		/**
  		 * Lookup table for turning Base64 alphabet positions (6 bits)
  		 * into output bytes.
  		 */
  		private static final byte ENCODE_WEBSAFE[] = {
  				'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
  				'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
  				'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
  				'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_',
  		};
  
  		final private byte[] tail;
  		/* package */ int tailLen;
  		private int count;
  
  		final public boolean do_padding;
  		final public boolean do_newline;
  		final public boolean do_cr;
  		final private byte[] alphabet;
  
  		public Encoder(int flags, byte[] output) {
  			this.output = output;
  
  			do_padding = (flags & NO_PADDING) == 0;
  			do_newline = (flags & NO_WRAP) == 0;
  			do_cr = (flags & CRLF) != 0;
  			alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;
  
  			tail = new byte[2];
  			tailLen = 0;
  
  			count = do_newline ? LINE_GROUPS : -1;
  		}
  
  		/**
  		 * @return an overestimate for the number of bytes {@code
  		 * len} bytes could encode to.
  		 */
  		public int maxOutputSize(int len) {
  			return len * 8/5 + 10;
  		}
  
  		public boolean process(byte[] input, int offset, int len, boolean finish) {
  			// Using local variables makes the encoder about 9% faster.
  			final byte[] alphabet = this.alphabet;
  			final byte[] output = this.output;
  			int op = 0;
  			int count = this.count;
  
  			int p = offset;
  			len += offset;
  			int v = -1;
  
  			// First we need to concatenate the tail of the previous call
  			// with any input bytes available now and see if we can empty
  			// the tail.
  
  			switch (tailLen) {
  				case 0:
  					// There was no tail.
  					break;
  
  				case 1:
  					if (p+2 <= len) {
  						// A 1-byte tail with at least 2 bytes of
  						// input available now.
  						v = ((tail[0] & 0xff) << 16) |
  								((input[p++] & 0xff) << 8) |
  								(input[p++] & 0xff);
  						tailLen = 0;
  					};
  					break;
  
  				case 2:
  					if (p+1 <= len) {
  						// A 2-byte tail with at least 1 byte of input.
  						v = ((tail[0] & 0xff) << 16) |
  								((tail[1] & 0xff) << 8) |
  								(input[p++] & 0xff);
  						tailLen = 0;
  					}
  					break;
  			}
  
  			if (v != -1) {
  				output[op++] = alphabet[(v >> 18) & 0x3f];
  				output[op++] = alphabet[(v >> 12) & 0x3f];
  				output[op++] = alphabet[(v >> 6) & 0x3f];
  				output[op++] = alphabet[v & 0x3f];
  				if (--count == 0) {
  					if (do_cr) output[op++] = '\r';
  					output[op++] = '\n';
  					count = LINE_GROUPS;
  				}
  			}
  
  			// At this point either there is no tail, or there are fewer
  			// than 3 bytes of input available.
  
  			// The main loop, turning 3 input bytes into 4 output bytes on
  			// each iteration.
  			while (p+3 <= len) {
  				v = ((input[p] & 0xff) << 16) |
  						((input[p+1] & 0xff) << 8) |
  						(input[p+2] & 0xff);
  				output[op] = alphabet[(v >> 18) & 0x3f];
  				output[op+1] = alphabet[(v >> 12) & 0x3f];
  				output[op+2] = alphabet[(v >> 6) & 0x3f];
  				output[op+3] = alphabet[v & 0x3f];
  				p += 3;
  				op += 4;
  				if (--count == 0) {
  					if (do_cr) output[op++] = '\r';
  					output[op++] = '\n';
  					count = LINE_GROUPS;
  				}
  			}
  
  			if (finish) {
  				// Finish up the tail of the input.  Note that we need to
  				// consume any bytes in tail before any bytes
  				// remaining in input; there should be at most two bytes
  				// total.
  
  				if (p-tailLen == len-1) {
  					int t = 0;
  					v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4;
  					tailLen -= t;
  					output[op++] = alphabet[(v >> 6) & 0x3f];
  					output[op++] = alphabet[v & 0x3f];
  					if (do_padding) {
  						output[op++] = '=';
  						output[op++] = '=';
  					}
  					if (do_newline) {
  						if (do_cr) output[op++] = '\r';
  						output[op++] = '\n';
  					}
  				} else if (p-tailLen == len-2) {
  					int t = 0;
  					v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) |
  							(((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2);
  					tailLen -= t;
  					output[op++] = alphabet[(v >> 12) & 0x3f];
  					output[op++] = alphabet[(v >> 6) & 0x3f];
  					output[op++] = alphabet[v & 0x3f];
  					if (do_padding) {
  						output[op++] = '=';
  					}
  					if (do_newline) {
  						if (do_cr) output[op++] = '\r';
  						output[op++] = '\n';
  					}
  				} else if (do_newline && op > 0 && count != LINE_GROUPS) {
  					if (do_cr) output[op++] = '\r';
  					output[op++] = '\n';
  				}
  
  				assert tailLen == 0;
  				assert p == len;
  			} else {
  				// Save the leftovers in tail to be consumed on the next
  				// call to encodeInternal.
  
  				if (p == len-1) {
  					tail[tailLen++] = input[p];
  				} else if (p == len-2) {
  					tail[tailLen++] = input[p];
  					tail[tailLen++] = input[p+1];
  				}
  			}
  
  			this.op = op;
  			this.count = count;
  
  			return true;
  		}
  	}
  
  	private Base64() { }   // don't instantiate
  
  	public static String toBase64(String s){
  		return encodeToString(s.getBytes(), NO_WRAP | URL_SAFE);
  	}
  
  	public static String fromBase64(String s)
  	{
  		return new String(decode(s, URL_SAFE));
  	}
  }
  