/commons/src/commons/utils/Base64.java

/*

 * This program is free software: you can redistribute it and/or modify it under

 * the terms of the GNU General Public License as published by the Free Software

 * Foundation, either version 3 of the License, or (at your option) any later

 * version.

 * 

 * This program is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more

 * details.

 * 

 * You should have received a copy of the GNU General Public License along with

 * this program. If not, see <http://www.gnu.org/licenses/>.

 */



package commons.utils;



import java.util.Arrays;



/**

 * A very fast and memory efficient class to encode and decode to and from BASE64 in full accordance with RFC 2045.<br>

 * <br>

 * On Windows XP sp1 with 1.4.2_04 and later ;), this encoder and decoder is about 10 times faster on small arrays (10 -

 * 1000 bytes) and 2-3 times as fast on larger arrays (10000 - 1000000 bytes) compared to

 * <code>sun.misc.Encoder()/Decoder()</code>.<br>

 * <br>

 * <p/>

 * On byte arrays the encoder is about 20% faster than Jakarta Commons Base64 Codec for encode and about 50% faster for

 * decoding large arrays. This implementation is about twice as fast on very small arrays (&lt 30 bytes). If

 * source/destination is a <code>String</code> this version is about three times as fast due to the fact that the

 * Commons Codec result has to be recoded to a <code>String</code> from <code>byte[]</code>, which is very expensive.<br>

 * <br>

 * <p/>

 * This encode/decode algorithm doesn't create any temporary arrays as many other codecs do, it only allocates the

 * resulting array. This produces less garbage and it is possible to handle arrays twice as large as algorithms that

 * create a temporary array. (E.g. Jakarta Commons Codec). It is unknown whether Sun's

 * <code>sun.misc.Encoder()/Decoder()</code> produce temporary arrays but since performance is quite low it probably

 * does.<br>

 * <br>

 * <p/>

 * The encoder produces the same output as the Sun one except that the Sun's encoder appends a trailing line separator

 * if the last character isn't a pad. Unclear why but it only adds to the length and is probably a side effect. Both are

 * in conformance with RFC 2045 though.<br>

 * Commons codec seem to always att a trailing line separator.<br>

 * <br>

 * <p/>

 * <b>Note!</b> The encode/decode method pairs (types) come in three versions with the <b>exact</b> same algorithm and

 * thus a lot of code redundancy. This is to not create any temporary arrays for transcoding to/from different format

 * types. The methods not used can simply be commented out.<br>

 * <br>

 * <p/>

 * There is also a "fast" version of all decode methods that works the same way as the normal ones, but har a few

 * demands on the decoded input. Normally though, these fast verions should be used if the source if the input is known

 * and it hasn't bee tampered with.<br>

 * <br>

 * <p/>

 * If you find the code useful or you find a bug, please send me a note at base64 @ miginfocom . com.

 * <p/>

 * Licence (BSD): ==============

 * <p/>

 * Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com) All rights reserved.

 * <p/>

 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the

 * following conditions are met: Redistributions of source code must retain the above copyright notice, this list of

 * conditions and the following disclaimer. Redistributions in binary form must reproduce the above copyright notice,

 * this list of conditions and the following disclaimer in the documentation and/or other materials provided with the

 * distribution. Neither the name of the MiG InfoCom AB nor the names of its contributors may be used to endorse or

 * promote products derived from this software without specific prior written permission.

 * <p/>

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,

 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */



public class Base64

{

	private static final char[]	CA	= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();

	private static final int[]	IA	= new int[256];

	

	static

	{

		Arrays.fill(IA, -1);

		for(int i = 0, iS = CA.length; i < iS; i++)

			IA[CA[i]] = i;

		IA['='] = 0;

	}

	

	// ****************************************************************************************

	// * char[] version

	// ****************************************************************************************



	/**

	* Encodes a raw byte array into a BASE64 <code>char[]</code> representation i accordance with RFC 2045.

	* 

	* @param sArr

	*            The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.

	* @param lineSep

	*            Optional "\r\n" after 76 characters, unless end of file.<br>

	*            No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a little

	*            faster.

	* @return A BASE64 encoded array. Never <code>null</code>.

	*/

	public static char[] encodeToChar(byte[] sArr, boolean lineSep)

	{

		// Check special case

		int sLen = sArr != null ? sArr.length : 0;

		if(sLen == 0)

			return new char[0];

		

		int eLen = (sLen / 3) * 3; // Length of even 24-bits.

		int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count

		int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array

		char[] dArr = new char[dLen];

		

		// Encode even 24-bits

		for(int s = 0, d = 0, cc = 0; s < eLen;)

		{

			// Copy next three bytes into lower 24 bits of int, paying attension to sign.

			int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);

			

			// Encode the int into four chars

			dArr[d++] = CA[(i >>> 18) & 0x3f];

			dArr[d++] = CA[(i >>> 12) & 0x3f];

			dArr[d++] = CA[(i >>> 6) & 0x3f];

			dArr[d++] = CA[i & 0x3f];

			

			// Add optional line separator

			if(lineSep && ++cc == 19 && d < dLen - 2)

			{

				dArr[d++] = '\r';

				dArr[d++] = '\n';

				cc = 0;

			}

		}

	

		// Pad and encode last bits if source isn't even 24 bits.

		int left = sLen - eLen; // 0 - 2.

		if(left > 0)

		{

			// Prepare the int

			int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);



			// Set last four chars

			dArr[dLen - 4] = CA[i >> 12];

			dArr[dLen - 3] = CA[(i >>> 6) & 0x3f];

			dArr[dLen - 2] = left == 2 ? CA[i & 0x3f] : '=';

			dArr[dLen - 1] = '=';

		}

		return dArr;

	}

	

	/**

	* Decodes a BASE64 encoded char array. All illegal characters will be ignored and can handle both arrays with and

	* without line separators.

	* 

	* @param sArr

	*            The source array. <code>null</code> or length 0 will return an empty array.

	* @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters

	*         (including '=') isn't divideable by 4. (I.e. definitely corrupted).

	*/

	public static byte[] decode(char[] sArr)

	{

		// Check special case

		int sLen = sArr != null ? sArr.length : 0;

		if(sLen == 0)

			return new byte[0];

		

		// Count illegal characters (including '\r', '\n') to know what size the returned array will be,

		// so we don't have to reallocate & copy it later.

		int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)

		for(int i = 0; i < sLen; i++)

			// If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.

			if(IA[sArr[i]] < 0)

				sepCnt++;

		

		// Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.

		if((sLen - sepCnt) % 4 != 0)

			return null;

		

		int pad = 0;

		for(int i = sLen; i > 1 && IA[sArr[--i]] <= 0;)

			if(sArr[i] == '=')

				pad++;

		

		int len = ((sLen - sepCnt) * 6 >> 3) - pad;

		

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		

		for(int s = 0, d = 0; d < len;)

		{

			// Assemble three bytes into an int from four "valid" characters.

			int i = 0;

			for(int j = 0; j < 4; j++)

			{ // j only increased if a valid char was found.

				int c = IA[sArr[s++]];

				if(c >= 0)

					i |= c << (18 - j * 6);

				else

					j--;

			}

			// Add the bytes

			dArr[d++] = (byte) (i >> 16);

			if(d < len)

			{

				dArr[d++] = (byte) (i >> 8);

				if(d < len)

					dArr[d++] = (byte) i;

			}

		}

		return dArr;

	}

	

	/**

	* Decodes a BASE64 encoded char array that is known to be resonably well formatted. The method is about twice as

	* fast as {@link #decode(char[])}. The preconditions are:<br>

	* + The array must have a line length of 76 chars OR no line separators at all (one line).<br>

	* + Line separator must be "\r\n", as specified in RFC 2045 + The array must not contain illegal characters within

	* the encoded string<br>

	* + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>

	* 

	* @param sArr

	*            The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.

	* @return The decoded array of bytes. May be of length 0.

	*/

	public static byte[] decodeFast(char[] sArr)

	{

		// Check special case

		int sLen = sArr.length;

		if(sLen == 0)

			return new byte[0];

		

		int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

		

		// Trim illegal chars from start

		while(sIx < eIx && IA[sArr[sIx]] < 0)

			sIx++;

		

		// Trim illegal chars from end

		while(eIx > 0 && IA[sArr[eIx]] < 0)

			eIx--;

		

		// get the padding count (=) (0, 1 or 2)

		int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.

		int cCnt = eIx - sIx + 1; // Content count including possible separators

		int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;

		

		int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		

		// Decode all but the last 0 - 2 bytes.

		int d = 0;

		for(int cc = 0, eLen = (len / 3) * 3; d < eLen;)

		{

			// Assemble three bytes into an int from four "valid" characters.

			int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

			

			// Add the bytes

			dArr[d++] = (byte) (i >> 16);

			dArr[d++] = (byte) (i >> 8);

			dArr[d++] = (byte) i;

			

			// If line separator, jump over it.

			if(sepCnt > 0 && ++cc == 19)

			{

				sIx += 2;

				cc = 0;

			}

		}

		

		if(d < len)

		{

			// Decode last 1-3 bytes (incl '=') into 1-3 bytes

			int i = 0;

			for(int j = 0; sIx <= eIx - pad; j++)

				i |= IA[sArr[sIx++]] << (18 - j * 6);



			for(int r = 16; d < len; r -= 8)

				dArr[d++] = (byte) (i >> r);

		}

		

		return dArr;

	}

	

	// ****************************************************************************************

	// * byte[] version

	// ****************************************************************************************

	

	/**

	* Encodes a raw byte array into a BASE64 <code>byte[]</code> representation i accordance with RFC 2045.

	* 

	* @param sArr

	*            The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.

	* @param lineSep

	*            Optional "\r\n" after 76 characters, unless end of file.<br>

	*            No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a little

	*            faster.

	* @return A BASE64 encoded array. Never <code>null</code>.

	*/

	public static byte[] encodeToByte(byte[] sArr, boolean lineSep)

	{

		// Check special case

		int sLen = sArr != null ? sArr.length : 0;

		if(sLen == 0)

			return new byte[0];

		

		int eLen = (sLen / 3) * 3; // Length of even 24-bits.

		int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count

		int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array

		byte[] dArr = new byte[dLen];

		

		// Encode even 24-bits

		for(int s = 0, d = 0, cc = 0; s < eLen;)

		{

			// Copy next three bytes into lower 24 bits of int, paying attension to sign.

			int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);

			

			// Encode the int into four chars

			dArr[d++] = (byte) CA[(i >>> 18) & 0x3f];

			dArr[d++] = (byte) CA[(i >>> 12) & 0x3f];

			dArr[d++] = (byte) CA[(i >>> 6) & 0x3f];

			dArr[d++] = (byte) CA[i & 0x3f];

			

			// Add optional line separator

			if(lineSep && ++cc == 19 && d < dLen - 2)

			{

				dArr[d++] = '\r';

				dArr[d++] = '\n';

				cc = 0;

			}

		}

		

		// Pad and encode last bits if source isn't an even 24 bits.

		int left = sLen - eLen; // 0 - 2.

		if(left > 0)

		{

			// Prepare the int

			int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);

			

			// Set last four chars

			dArr[dLen - 4] = (byte) CA[i >> 12];

			dArr[dLen - 3] = (byte) CA[(i >>> 6) & 0x3f];

			dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';

			dArr[dLen - 1] = '=';

		}

		return dArr;

	}

	

	/**

	* Decodes a BASE64 encoded byte array. All illegal characters will be ignored and can handle both arrays with and

	* without line separators.

	* 

	* @param sArr

	*            The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.

	* @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters

	*         (including '=') isn't divideable by 4. (I.e. definitely corrupted).

	*/

	public static byte[] decode(byte[] sArr)

	{

		// Check special case

		int sLen = sArr.length;

		

		// Count illegal characters (including '\r', '\n') to know what size the returned array will be,

		// so we don't have to reallocate & copy it later.

		int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)

		for(int i = 0; i < sLen; i++)

			// If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.

			if(IA[sArr[i] & 0xff] < 0)

				sepCnt++;

		

		// Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.

		if((sLen - sepCnt) % 4 != 0)

			return null;

		

		int pad = 0;

		for(int i = sLen; i > 1 && IA[sArr[--i] & 0xff] <= 0;)

			if(sArr[i] == '=')

				pad++;

		

		int len = ((sLen - sepCnt) * 6 >> 3) - pad;

		

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		

		for(int s = 0, d = 0; d < len;)

		{

			// Assemble three bytes into an int from four "valid" characters.

			int i = 0;

			for(int j = 0; j < 4; j++)

			{ // j only increased if a valid char was found.

				int c = IA[sArr[s++] & 0xff];

				if(c >= 0)

					i |= c << (18 - j * 6);

				else

					j--;

			}

			

			// Add the bytes

			dArr[d++] = (byte) (i >> 16);

			if(d < len)

			{

				dArr[d++] = (byte) (i >> 8);

				if(d < len)

					dArr[d++] = (byte) i;

			}

		}

		

		return dArr;

	}

	

	/**

	* Decodes a BASE64 encoded byte array that is known to be resonably well formatted. The method is about twice as

	* fast as {@link #decode(byte[])}. The preconditions are:<br>

	* + The array must have a line length of 76 chars OR no line separators at all (one line).<br>

	* + Line separator must be "\r\n", as specified in RFC 2045 + The array must not contain illegal characters within

	* the encoded string<br>

	* + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>

	* 

	* @param sArr

	*            The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.

	* @return The decoded array of bytes. May be of length 0.

	*/

	public static byte[] decodeFast(byte[] sArr)

	{

		// Check special case

		int sLen = sArr.length;

		if(sLen == 0)

			return new byte[0];

		

		int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

		

		// Trim illegal chars from start

		while(sIx < eIx && IA[sArr[sIx] & 0xff] < 0)

			sIx++;

		

		// Trim illegal chars from end

		while(eIx > 0 && IA[sArr[eIx] & 0xff] < 0)

			eIx--;

		

		// get the padding count (=) (0, 1 or 2)

		int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.

		int cCnt = eIx - sIx + 1; // Content count including possible separators

		int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;

		

		int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		

		// Decode all but the last 0 - 2 bytes.

		int d = 0;

		for(int cc = 0, eLen = (len / 3) * 3; d < eLen;)

		{

			// Assemble three bytes into an int from four "valid" characters.

			int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

			

			// Add the bytes

			dArr[d++] = (byte) (i >> 16);

			dArr[d++] = (byte) (i >> 8);

			dArr[d++] = (byte) i;

			

			// If line separator, jump over it.

			if(sepCnt > 0 && ++cc == 19)

			{

				sIx += 2;

				cc = 0;

			}

		}

		

		if(d < len)

		{

			// Decode last 1-3 bytes (incl '=') into 1-3 bytes

			int i = 0;

			for(int j = 0; sIx <= eIx - pad; j++)

				i |= IA[sArr[sIx++]] << (18 - j * 6);

			

			for(int r = 16; d < len; r -= 8)

				dArr[d++] = (byte) (i >> r);

		}

		

		return dArr;

	}

	

	// ****************************************************************************************

	// * String version

	// ****************************************************************************************

	

	/**

	* Encodes a raw byte array into a BASE64 <code>String</code> representation i accordance with RFC 2045.

	* 

	* @param sArr

	*            The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.

	* @param lineSep

	*            Optional "\r\n" after 76 characters, unless end of file.<br>

	*            No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a little

	*            faster.

	* @return A BASE64 encoded array. Never <code>null</code>.

	*/

	public static String encodeToString(byte[] sArr, boolean lineSep)

	{

		// Reuse char[] since we can't create a String incrementally anyway and StringBuffer/Builder would be slower.

		return new String(encodeToChar(sArr, lineSep));

	}

	

	/**

	* Decodes a BASE64 encoded <code>String</code>. All illegal characters will be ignored and can handle both strings

	* with and without line separators.<br>

	* <b>Note!</b> It can be up to about 2x the speed to call <code>decode(str.toCharArray())</code> instead. That will

	* create a temporary array though. This version will use <code>str.charAt(i)</code> to iterate the string.

	* 

	* @param str

	*            The source string. <code>null</code> or length 0 will return an empty array.

	* @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters

	*         (including '=') isn't divideable by 4. (I.e. definitely corrupted).

	*/

	public static byte[] decode(String str)

	{

		// Check special case

		int sLen = str != null ? str.length() : 0;

		if(sLen == 0)

			return new byte[0];

		

		// Count illegal characters (including '\r', '\n') to know what size the returned array will be,

		// so we don't have to reallocate & copy it later.

		int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)

		for(int i = 0; i < sLen; i++)

			// If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.

			if(IA[str.charAt(i)] < 0)

				sepCnt++;

		

		// Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.

		if((sLen - sepCnt) % 4 != 0)

			return null;

		

		// Count '=' at end

		int pad = 0;

		for(int i = sLen; i > 1 && IA[str.charAt(--i)] <= 0;)

			if(str.charAt(i) == '=')

				pad++;

		

		int len = ((sLen - sepCnt) * 6 >> 3) - pad;

		

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		

		for(int s = 0, d = 0; d < len;)

		{

			// Assemble three bytes into an int from four "valid" characters.

			int i = 0;

			for(int j = 0; j < 4; j++)

			{ // j only increased if a valid char was found.

				int c = IA[str.charAt(s++)];

				if(c >= 0)

					i |= c << (18 - j * 6);

				else

					j--;

			}

			// Add the bytes

			dArr[d++] = (byte) (i >> 16);

			if(d < len)

			{

				dArr[d++] = (byte) (i >> 8);

				if(d < len)

					dArr[d++] = (byte) i;

			}

		}

		return dArr;

	}

	

	/**

	* Decodes a BASE64 encoded string that is known to be resonably well formatted. The method is about twice as fast

	* as {@link #decode(String)}. The preconditions are:<br>

	* + The array must have a line length of 76 chars OR no line separators at all (one line).<br>

	* + Line separator must be "\r\n", as specified in RFC 2045 + The array must not contain illegal characters within

	* the encoded string<br>

	* + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>

	* 

	* @param s

	*            The source string. Length 0 will return an empty array. <code>null</code> will throw an exception.

	* @return The decoded array of bytes. May be of length 0.

	*/

	public static byte[] decodeFast(String s)

	{

		// Check special case

		int sLen = s.length();

		if(sLen == 0)

			return new byte[0];

		

		int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

		

		// Trim illegal chars from start

		while(sIx < eIx && IA[s.charAt(sIx) & 0xff] < 0)

			sIx++;

		

		// Trim illegal chars from end

		while(eIx > 0 && IA[s.charAt(eIx) & 0xff] < 0)

			eIx--;

		

		// get the padding count (=) (0, 1 or 2)

		int pad = s.charAt(eIx) == '=' ? (s.charAt(eIx - 1) == '=' ? 2 : 1) : 0; // Count '=' at end.

		int cCnt = eIx - sIx + 1; // Content count including possible separators

		int sepCnt = sLen > 76 ? (s.charAt(76) == '\r' ? cCnt / 78 : 0) << 1 : 0;

		

		int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes

		byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

		

		// Decode all but the last 0 - 2 bytes.

		int d = 0;

		for(int cc = 0, eLen = (len / 3) * 3; d < eLen;)

		{

			// Assemble three bytes into an int from four "valid" characters.

			int i = IA[s.charAt(sIx++)] << 18 | IA[s.charAt(sIx++)] << 12 | IA[s.charAt(sIx++)] << 6

				| IA[s.charAt(sIx++)];

			

			// Add the bytes

			dArr[d++] = (byte) (i >> 16);

			dArr[d++] = (byte) (i >> 8);

			dArr[d++] = (byte) i;

			

			// If line separator, jump over it.

			if(sepCnt > 0 && ++cc == 19)

			{

				sIx += 2;

				cc = 0;

			}

		}

		

		if(d < len)

		{

			// Decode last 1-3 bytes (incl '=') into 1-3 bytes

			int i = 0;

			for(int j = 0; sIx <= eIx - pad; j++)

				i |= IA[s.charAt(sIx++)] << (18 - j * 6);



			for(int r = 16; d < len; r -= 8)

				dArr[d++] = (byte) (i >> r);

		}

		

		return dArr;

	}

}