| /* |
| * 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 |
| * |
| * 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 libcore.io; |
| |
| import java.nio.charset.Charsets; |
| import libcore.util.EmptyArray; |
| |
| /** |
| * <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 EmptyArray.BYTE; |
| } |
| // 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; |
| } |
| return new String(out, 0, index, Charsets.US_ASCII); |
| } |
| } |