package org.jaudiotagger.tag.vorbiscomment.util;
import org.jaudiotagger.audio.generic.Utils;
/**
* Base64Coder
*/
public class Base64Coder
{
// Mapping table from 6-bit nibbles to Base64 characters.
private static final char[] map1 = new char[64];
static
{
int i = 0;
for (char c = 'A'; c <= 'Z'; c++)
{
map1[i++] = c;
}
for (char c = 'a'; c <= 'z'; c++)
{
map1[i++] = c;
}
for (char c = '0'; c <= '9'; c++)
{
map1[i++] = c;
}
map1[i++] = '+';
map1[i++] = '/';
}
// Mapping table from Base64 characters to 6-bit nibbles.
private static final byte[] map2 = new byte[128];
static
{
for (int i = 0; i < map2.length; i++)
{
map2[i] = -1;
}
for (int i = 0; i < 64; i++)
{
map2[map1[i]] = (byte) i;
}
}
/**
* Encodes a string into Base64 format.
* No blanks or line breaks are inserted.
*
* @param s a String to be encoded.
* @return A String with the Base64 encoded data.
*/
public static String encode(final String s)
{
return new String(encode(Utils.getDefaultBytes(s, "ISO-8859-1")));
}
/**
* Encodes a byte array into Base64 format.
* No blanks or line breaks are inserted.
*
* @param in an array containing the data bytes to be encoded.
* @return A character array with the Base64 encoded data.
*/
public static char[] encode(final byte[] in)
{
final int iLen = in.length;
final int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
final int oLen = ((iLen + 2) / 3) * 4; // output length including padding
final char[] out = new char[oLen];
int ip = 0;
int op = 0;
while (ip < iLen)
{
final int i0 = in[ip++] & 0xff;
final int i1 = ip < iLen ? in[ip++] & 0xff : 0;
final int i2 = ip < iLen ? in[ip++] & 0xff : 0;
final int o0 = i0 >>> 2;
final int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
final int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
final int o3 = i2 & 0x3F;
out[op++] = map1[o0];
out[op++] = map1[o1];
out[op] = op < oDataLen ? map1[o2] : '=';
op++;
out[op] = op < oDataLen ? map1[o3] : '=';
op++;
}
return out;
}
/**
* Decodes a Base64 string.
*
* @param s a Base64 String to be decoded.
* @return An array containing the decoded data bytes.
* @throws IllegalArgumentException if the input is not valid Base64 encoded data.
*/
public static byte[] decode(final String s)
{
return decode(s.toCharArray());
}
/**
* Decodes Base64 data.
* No blanks or line breaks are allowed within the Base64 encoded data.
*
* @param in a character array containing the Base64 encoded data.
* @return An array containing the decoded data bytes.
* @throws IllegalArgumentException if the input is not valid Base64 encoded data.
*/
public static byte[] decode(final char[] in)
{
int iLen = in.length;
if (iLen % 4 != 0)
{
throw new IllegalArgumentException("Length of Base64 encoded input string is not a multiple of 4.");
}
while (iLen > 0 && in[iLen - 1] == '=')
{
iLen--;
}
final int oLen = (iLen * 3) / 4;
final byte[] out = new byte[oLen];
int ip = 0;
int op = 0;
while (ip < iLen)
{
final int i0 = in[ip++];
final int i1 = in[ip++];
final int i2 = ip < iLen ? in[ip++] : 'A';
final int i3 = ip < iLen ? in[ip++] : 'A';
if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
{
throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
}
final int b0 = map2[i0];
final int b1 = map2[i1];
final int b2 = map2[i2];
final int b3 = map2[i3];
if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
{
throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
}
final int o0 = (b0 << 2) | (b1 >>> 4);
final int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
final int o2 = ((b2 & 3) << 6) | b3;
out[op++] = (byte) o0;
if (op < oLen)
{
out[op++] = (byte) o1;
}
if (op < oLen)
{
out[op++] = (byte) o2;
}
}
return out;
}
}
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