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package de.pfabulist.kleinod.encode;
import java.util.HashMap;
import java.util.Map;
/**
* ** BEGIN LICENSE BLOCK *****
* BSD License (2 clause)
* Copyright (c) 2006 - 2016, Stephan Pfab
* All rights reserved.
*
* 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.
*
* 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 Stephan Pfab 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.
* **** END LICENSE BLOCK ****
*/
public final class Base16 {
private static final Map toNum = new HashMap<>();
private static final char[] HEX_CHARS = {
'0', '1', '2', '3',
'4', '5', '6', '7',
'8', '9', 'a', 'b',
'c', 'd', 'e', 'f', };
private Base16() {}
static {
synchronized( toNum ) {
byte[] by = new byte[ 1 ];
for( int b = Byte.MIN_VALUE; b <= Byte.MAX_VALUE; b++ ) {
by[ 0 ] = (byte) b;
toNum.put( encode( by ), by[ 0 ] );
}
}
}
public static String encode( byte[] src ) {
char buf[] = new char[ src.length * 2 ];
for( int i = 0, x = 0; i < src.length; i++ ) {
buf[ x++ ] = HEX_CHARS[ ( src[ i ] >>> 4 ) & 0xf ];
buf[ x++ ] = HEX_CHARS[ src[ i ] & 0xf ];
}
return new String( buf );
}
public static byte[] decode( String src ) {
if( ( src.length() / 2 ) * 2 < src.length() ) {
throw new IllegalArgumentException( "string's length is odd " + src );
}
byte[] ret = new byte[ src.length() / 2 ];
for( int i = 0; i < src.length(); i += 2 ) {
final String substring = src.substring( i, i + 2 );
if( !toNum.containsKey( substring ) ) {
throw new IllegalArgumentException( "not a base16 encoded string: " + src );
}
ret[ i / 2 ] = toNum.get( substring );
}
return ret;
}
}