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package com.dslplatform.json;
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.
* 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 sun.misc.Encoder()/Decoder().
*
* 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 (< 30 bytes). If source/destination is a String this
* version is about three times as fast due to the fact that the Commons Codec result has to be recoded
* to a String from byte[], which is very expensive.
*
* 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 sun.misc.Encoder()/Decoder() produce temporary arrays but since performance
* is quite low it probably does.
*
* 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.
* Commons codec seem to always att a trailing line separator.
*
* Note!
* The encode/decode method pairs (types) come in three versions with the exact 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.
*
* 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.
*
* If you find the code useful or you find a bug, please send me a note at base64 @ miginfocom . com.
*
* Licence (BSD):
* ==============
*
* Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com)
* 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.
* 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.
*
* 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.
*
* @version 2.2
* @author Mikael Grev
* Date: 2004-aug-02
* Time: 11:31:11
*/
abstract class Base64 {
private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
private static final byte[] BA;
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;
BA = new byte[CA.length];
for (int i = 0; i < CA.length; i++) {
BA[i] = (byte)CA[i];
}
}
static int encodeToBytes(byte[] sArr, byte[] dArr, final int start) {
final int sLen = sArr.length;
final int eLen = (sLen / 3) * 3; // Length of even 24-bits.
final int dLen = ((sLen - 1) / 3 + 1) << 2; // Returned character count
// Encode even 24-bits
for (int s = 0, d = start; 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++] = BA[(i >>> 18) & 0x3f];
dArr[d++] = BA[(i >>> 12) & 0x3f];
dArr[d++] = BA[(i >>> 6) & 0x3f];
dArr[d++] = BA[i & 0x3f];
}
// 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[start + dLen - 4] = BA[i >> 12];
dArr[start + dLen - 3] = BA[(i >>> 6) & 0x3f];
dArr[start + dLen - 2] = left == 2 ? BA[i & 0x3f] : (byte)'=';
dArr[start + dLen - 1] = '=';
}
return dLen;
}
static int findEnd(final byte[] sArr, final int start) {
for (int i = start; i < sArr.length; i++)
if (IA[sArr[i] & 0xff] < 0)
return i;
return sArr.length;
}
private final static byte[] EMPTY_ARRAY = new byte[0];
static byte[] decodeFast(final byte[] sArr, final int start, final int end) {
// Check special case
int sLen = end - start;
if (sLen == 0)
return EMPTY_ARRAY;
int sIx = start, eIx = end - 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)
final int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.
final int cCnt = eIx - sIx + 1; // Content count including possible separators
final int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
final int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
final 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;
}
}
