Android Open Source - wototoplayer Base64

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License

The source code is released under:

Copyright (c) 2015, Chris Greenhalgh All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met...

Java Source Code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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
 */*from ww w . j  av a2 s . c o  m*/
 *     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.
 */

/**
 * @author Alexander Y. Kleymenov
 */

package com.squareup.okhttp.internal;

import java.io.UnsupportedEncodingException;

import static com.squareup.okhttp.internal.Util.EMPTY_BYTE_ARRAY;

/**
 * <a href="http://www.ietf.org/rfc/rfc2045.txt">Base64</a> encoder/decoder.
 * In violation of the RFC, this encoder doesn't wrap lines at 76 columns.
 */
public final class Base64 {
  private Base64() {
  }

  public static byte[] decode(byte[] in) {
    return decode(in, in.length);
  }

  public static byte[] decode(byte[] in, int len) {
    // approximate output length
    int length = len / 4 * 3;
    // return an empty array on empty or short input without padding
    if (length == 0) {
      return EMPTY_BYTE_ARRAY;
    }
    // temporary array
    byte[] out = new byte[length];
    // number of padding characters ('=')
    int pad = 0;
    byte chr;
    // compute the number of the padding characters
    // and adjust the length of the input
    for (; ; len--) {
      chr = in[len - 1];
      // skip the neutral characters
      if ((chr == '\n') || (chr == '\r') || (chr == ' ') || (chr == '\t')) {
        continue;
      }
      if (chr == '=') {
        pad++;
      } else {
        break;
      }
    }
    // index in the output array
    int outIndex = 0;
    // index in the input array
    int inIndex = 0;
    // holds the value of the input character
    int bits = 0;
    // holds the value of the input quantum
    int quantum = 0;
    for (int i = 0; i < len; i++) {
      chr = in[i];
      // skip the neutral characters
      if ((chr == '\n') || (chr == '\r') || (chr == ' ') || (chr == '\t')) {
        continue;
      }
      if ((chr >= 'A') && (chr <= 'Z')) {
        // char ASCII value
        //  A    65    0
        //  Z    90    25 (ASCII - 65)
        bits = chr - 65;
      } else if ((chr >= 'a') && (chr <= 'z')) {
        // char ASCII value
        //  a    97    26
        //  z    122   51 (ASCII - 71)
        bits = chr - 71;
      } else if ((chr >= '0') && (chr <= '9')) {
        // char ASCII value
        //  0    48    52
        //  9    57    61 (ASCII + 4)
        bits = chr + 4;
      } else if (chr == '+') {
        bits = 62;
      } else if (chr == '/') {
        bits = 63;
      } else {
        return null;
      }
      // append the value to the quantum
      quantum = (quantum << 6) | (byte) bits;
      if (inIndex % 4 == 3) {
        // 4 characters were read, so make the output:
        out[outIndex++] = (byte) (quantum >> 16);
        out[outIndex++] = (byte) (quantum >> 8);
        out[outIndex++] = (byte) quantum;
      }
      inIndex++;
    }
    if (pad > 0) {
      // adjust the quantum value according to the padding
      quantum = quantum << (6 * pad);
      // make output
      out[outIndex++] = (byte) (quantum >> 16);
      if (pad == 1) {
        out[outIndex++] = (byte) (quantum >> 8);
      }
    }
    // create the resulting array
    byte[] result = new byte[outIndex];
    System.arraycopy(out, 0, result, 0, outIndex);
    return result;
  }

  private static final byte[] MAP = new byte[] {
      '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', '+', '/'
  };

  public static String encode(byte[] in) {
    int length = (in.length + 2) * 4 / 3;
    byte[] out = new byte[length];
    int index = 0, end = in.length - in.length % 3;
    for (int i = 0; i < end; i += 3) {
      out[index++] = MAP[(in[i] & 0xff) >> 2];
      out[index++] = MAP[((in[i] & 0x03) << 4) | ((in[i + 1] & 0xff) >> 4)];
      out[index++] = MAP[((in[i + 1] & 0x0f) << 2) | ((in[i + 2] & 0xff) >> 6)];
      out[index++] = MAP[(in[i + 2] & 0x3f)];
    }
    switch (in.length % 3) {
      case 1:
        out[index++] = MAP[(in[end] & 0xff) >> 2];
        out[index++] = MAP[(in[end] & 0x03) << 4];
        out[index++] = '=';
        out[index++] = '=';
        break;
      case 2:
        out[index++] = MAP[(in[end] & 0xff) >> 2];
        out[index++] = MAP[((in[end] & 0x03) << 4) | ((in[end + 1] & 0xff) >> 4)];
        out[index++] = MAP[((in[end + 1] & 0x0f) << 2)];
        out[index++] = '=';
        break;
    }
    try {
      return new String(out, 0, index, "US-ASCII");
    } catch (UnsupportedEncodingException e) {
      throw new AssertionError(e);
    }
  }
}

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