| /* |
| * Copyright (C) 2010 The Android Open Source Project |
| * |
| * Licensed 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. |
| */ |
| |
| package android.util; |
| |
| import java.io.UnsupportedEncodingException; |
| |
| /** |
| * Utilities for encoding and decoding the Base64 representation of |
| * binary data. See RFCs <a |
| * href="http://www.ietf.org/rfc/rfc2045.txt">2045</a> and <a |
| * href="http://www.ietf.org/rfc/rfc3548.txt">3548</a>. |
| */ |
| public class Base64 { |
| /** |
| * Default values for encoder/decoder flags. |
| */ |
| public static final int DEFAULT = 0; |
| |
| /** |
| * Encoder flag bit to omit the padding '=' characters at the end |
| * of the output (if any). |
| */ |
| public static final int NO_PADDING = 1; |
| |
| /** |
| * Encoder flag bit to omit all line terminators (i.e., the output |
| * will be on one long line). |
| */ |
| public static final int NO_WRAP = 2; |
| |
| /** |
| * Encoder flag bit to indicate lines should be terminated with a |
| * CRLF pair instead of just an LF. Has no effect if {@code |
| * NO_WRAP} is specified as well. |
| */ |
| public static final int CRLF = 4; |
| |
| /** |
| * Encoder/decoder flag bit to indicate using the "URL and |
| * filename safe" variant of Base64 (see RFC 3548 section 4) where |
| * {@code -} and {@code _} are used in place of {@code +} and |
| * {@code /}. |
| */ |
| public static final int URL_SAFE = 8; |
| |
| /** |
| * Flag to pass to {@link Base64OutputStream} to indicate that it |
| * should not close the output stream it is wrapping when it |
| * itself is closed. |
| */ |
| public static final int NO_CLOSE = 16; |
| |
| // -------------------------------------------------------- |
| // shared code |
| // -------------------------------------------------------- |
| |
| /* package */ static abstract class Coder { |
| public byte[] output; |
| public int op; |
| |
| /** |
| * Encode/decode another block of input data. this.output is |
| * provided by the caller, and must be big enough to hold all |
| * the coded data. On exit, this.opwill be set to the length |
| * of the coded data. |
| * |
| * @param finish true if this is the final call to process for |
| * this object. Will finalize the coder state and |
| * include any final bytes in the output. |
| * |
| * @return true if the input so far is good; false if some |
| * error has been detected in the input stream.. |
| */ |
| public abstract boolean process(byte[] input, int offset, int len, boolean finish); |
| |
| /** |
| * @return the maximum number of bytes a call to process() |
| * could produce for the given number of input bytes. This may |
| * be an overestimate. |
| */ |
| public abstract int maxOutputSize(int len); |
| } |
| |
| // -------------------------------------------------------- |
| // decoding |
| // -------------------------------------------------------- |
| |
| /** |
| * Decode the Base64-encoded data in input and return the data in |
| * a new byte array. |
| * |
| * <p>The padding '=' characters at the end are considered optional, but |
| * if any are present, there must be the correct number of them. |
| * |
| * @param str the input String to decode, which is converted to |
| * bytes using the default charset |
| * @param flags controls certain features of the decoded output. |
| * Pass {@code DEFAULT} to decode standard Base64. |
| * |
| * @throws IllegalArgumentException if the input contains |
| * incorrect padding |
| */ |
| public static byte[] decode(String str, int flags) { |
| return decode(str.getBytes(), flags); |
| } |
| |
| /** |
| * Decode the Base64-encoded data in input and return the data in |
| * a new byte array. |
| * |
| * <p>The padding '=' characters at the end are considered optional, but |
| * if any are present, there must be the correct number of them. |
| * |
| * @param input the input array to decode |
| * @param flags controls certain features of the decoded output. |
| * Pass {@code DEFAULT} to decode standard Base64. |
| * |
| * @throws IllegalArgumentException if the input contains |
| * incorrect padding |
| */ |
| public static byte[] decode(byte[] input, int flags) { |
| return decode(input, 0, input.length, flags); |
| } |
| |
| /** |
| * Decode the Base64-encoded data in input and return the data in |
| * a new byte array. |
| * |
| * <p>The padding '=' characters at the end are considered optional, but |
| * if any are present, there must be the correct number of them. |
| * |
| * @param input the data to decode |
| * @param offset the position within the input array at which to start |
| * @param len the number of bytes of input to decode |
| * @param flags controls certain features of the decoded output. |
| * Pass {@code DEFAULT} to decode standard Base64. |
| * |
| * @throws IllegalArgumentException if the input contains |
| * incorrect padding |
| */ |
| public static byte[] decode(byte[] input, int offset, int len, int flags) { |
| // Allocate space for the most data the input could represent. |
| // (It could contain less if it contains whitespace, etc.) |
| Decoder decoder = new Decoder(flags, new byte[len*3/4]); |
| |
| if (!decoder.process(input, offset, len, true)) { |
| throw new IllegalArgumentException("bad base-64"); |
| } |
| |
| // Maybe we got lucky and allocated exactly enough output space. |
| if (decoder.op == decoder.output.length) { |
| return decoder.output; |
| } |
| |
| // Need to shorten the array, so allocate a new one of the |
| // right size and copy. |
| byte[] temp = new byte[decoder.op]; |
| System.arraycopy(decoder.output, 0, temp, 0, decoder.op); |
| return temp; |
| } |
| |
| /* package */ static class Decoder extends Coder { |
| /** |
| * Lookup table for turning bytes into their position in the |
| * Base64 alphabet. |
| */ |
| private static final int DECODE[] = { |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, |
| 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, |
| -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, |
| 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, |
| -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, |
| 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| }; |
| |
| /** |
| * Decode lookup table for the "web safe" variant (RFC 3548 |
| * sec. 4) where - and _ replace + and /. |
| */ |
| private static final int DECODE_WEBSAFE[] = { |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, |
| 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, |
| -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, |
| 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, |
| -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, |
| 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| }; |
| |
| /** Non-data values in the DECODE arrays. */ |
| private static final int SKIP = -1; |
| private static final int EQUALS = -2; |
| |
| /** |
| * States 0-3 are reading through the next input tuple. |
| * State 4 is having read one '=' and expecting exactly |
| * one more. |
| * State 5 is expecting no more data or padding characters |
| * in the input. |
| * State 6 is the error state; an error has been detected |
| * in the input and no future input can "fix" it. |
| */ |
| private int state; // state number (0 to 6) |
| private int value; |
| |
| final private int[] alphabet; |
| |
| public Decoder(int flags, byte[] output) { |
| this.output = output; |
| |
| alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE; |
| state = 0; |
| value = 0; |
| } |
| |
| /** |
| * @return an overestimate for the number of bytes {@code |
| * len} bytes could decode to. |
| */ |
| public int maxOutputSize(int len) { |
| return len * 3/4 + 10; |
| } |
| |
| /** |
| * Decode another block of input data. |
| * |
| * @return true if the state machine is still healthy. false if |
| * bad base-64 data has been detected in the input stream. |
| */ |
| public boolean process(byte[] input, int offset, int len, boolean finish) { |
| if (this.state == 6) return false; |
| |
| int p = offset; |
| len += offset; |
| |
| // Using local variables makes the decoder about 12% |
| // faster than if we manipulate the member variables in |
| // the loop. (Even alphabet makes a measurable |
| // difference, which is somewhat surprising to me since |
| // the member variable is final.) |
| int state = this.state; |
| int value = this.value; |
| int op = 0; |
| final byte[] output = this.output; |
| final int[] alphabet = this.alphabet; |
| |
| while (p < len) { |
| // Try the fast path: we're starting a new tuple and the |
| // next four bytes of the input stream are all data |
| // bytes. This corresponds to going through states |
| // 0-1-2-3-0. We expect to use this method for most of |
| // the data. |
| // |
| // If any of the next four bytes of input are non-data |
| // (whitespace, etc.), value will end up negative. (All |
| // the non-data values in decode are small negative |
| // numbers, so shifting any of them up and or'ing them |
| // together will result in a value with its top bit set.) |
| // |
| // You can remove this whole block and the output should |
| // be the same, just slower. |
| if (state == 0) { |
| while (p+4 <= len && |
| (value = ((alphabet[input[p] & 0xff] << 18) | |
| (alphabet[input[p+1] & 0xff] << 12) | |
| (alphabet[input[p+2] & 0xff] << 6) | |
| (alphabet[input[p+3] & 0xff]))) >= 0) { |
| output[op+2] = (byte) value; |
| output[op+1] = (byte) (value >> 8); |
| output[op] = (byte) (value >> 16); |
| op += 3; |
| p += 4; |
| } |
| if (p >= len) break; |
| } |
| |
| // The fast path isn't available -- either we've read a |
| // partial tuple, or the next four input bytes aren't all |
| // data, or whatever. Fall back to the slower state |
| // machine implementation. |
| |
| int d = alphabet[input[p++] & 0xff]; |
| |
| switch (state) { |
| case 0: |
| if (d >= 0) { |
| value = d; |
| ++state; |
| } else if (d != SKIP) { |
| this.state = 6; |
| return false; |
| } |
| break; |
| |
| case 1: |
| if (d >= 0) { |
| value = (value << 6) | d; |
| ++state; |
| } else if (d != SKIP) { |
| this.state = 6; |
| return false; |
| } |
| break; |
| |
| case 2: |
| if (d >= 0) { |
| value = (value << 6) | d; |
| ++state; |
| } else if (d == EQUALS) { |
| // Emit the last (partial) output tuple; |
| // expect exactly one more padding character. |
| output[op++] = (byte) (value >> 4); |
| state = 4; |
| } else if (d != SKIP) { |
| this.state = 6; |
| return false; |
| } |
| break; |
| |
| case 3: |
| if (d >= 0) { |
| // Emit the output triple and return to state 0. |
| value = (value << 6) | d; |
| output[op+2] = (byte) value; |
| output[op+1] = (byte) (value >> 8); |
| output[op] = (byte) (value >> 16); |
| op += 3; |
| state = 0; |
| } else if (d == EQUALS) { |
| // Emit the last (partial) output tuple; |
| // expect no further data or padding characters. |
| output[op+1] = (byte) (value >> 2); |
| output[op] = (byte) (value >> 10); |
| op += 2; |
| state = 5; |
| } else if (d != SKIP) { |
| this.state = 6; |
| return false; |
| } |
| break; |
| |
| case 4: |
| if (d == EQUALS) { |
| ++state; |
| } else if (d != SKIP) { |
| this.state = 6; |
| return false; |
| } |
| break; |
| |
| case 5: |
| if (d != SKIP) { |
| this.state = 6; |
| return false; |
| } |
| break; |
| } |
| } |
| |
| if (!finish) { |
| // We're out of input, but a future call could provide |
| // more. |
| this.state = state; |
| this.value = value; |
| this.op = op; |
| return true; |
| } |
| |
| // Done reading input. Now figure out where we are left in |
| // the state machine and finish up. |
| |
| switch (state) { |
| case 0: |
| // Output length is a multiple of three. Fine. |
| break; |
| case 1: |
| // Read one extra input byte, which isn't enough to |
| // make another output byte. Illegal. |
| this.state = 6; |
| return false; |
| case 2: |
| // Read two extra input bytes, enough to emit 1 more |
| // output byte. Fine. |
| output[op++] = (byte) (value >> 4); |
| break; |
| case 3: |
| // Read three extra input bytes, enough to emit 2 more |
| // output bytes. Fine. |
| output[op++] = (byte) (value >> 10); |
| output[op++] = (byte) (value >> 2); |
| break; |
| case 4: |
| // Read one padding '=' when we expected 2. Illegal. |
| this.state = 6; |
| return false; |
| case 5: |
| // Read all the padding '='s we expected and no more. |
| // Fine. |
| break; |
| } |
| |
| this.state = state; |
| this.op = op; |
| return true; |
| } |
| } |
| |
| // -------------------------------------------------------- |
| // encoding |
| // -------------------------------------------------------- |
| |
| /** |
| * Base64-encode the given data and return a newly allocated |
| * String with the result. |
| * |
| * @param input the data to encode |
| * @param flags controls certain features of the encoded output. |
| * Passing {@code DEFAULT} results in output that |
| * adheres to RFC 2045. |
| */ |
| public static String encodeToString(byte[] input, int flags) { |
| try { |
| return new String(encode(input, flags), "US-ASCII"); |
| } catch (UnsupportedEncodingException e) { |
| // US-ASCII is guaranteed to be available. |
| throw new AssertionError(e); |
| } |
| } |
| |
| /** |
| * Base64-encode the given data and return a newly allocated |
| * String with the result. |
| * |
| * @param input the data to encode |
| * @param offset the position within the input array at which to |
| * start |
| * @param len the number of bytes of input to encode |
| * @param flags controls certain features of the encoded output. |
| * Passing {@code DEFAULT} results in output that |
| * adheres to RFC 2045. |
| */ |
| public static String encodeToString(byte[] input, int offset, int len, int flags) { |
| try { |
| return new String(encode(input, offset, len, flags), "US-ASCII"); |
| } catch (UnsupportedEncodingException e) { |
| // US-ASCII is guaranteed to be available. |
| throw new AssertionError(e); |
| } |
| } |
| |
| /** |
| * Base64-encode the given data and return a newly allocated |
| * byte[] with the result. |
| * |
| * @param input the data to encode |
| * @param flags controls certain features of the encoded output. |
| * Passing {@code DEFAULT} results in output that |
| * adheres to RFC 2045. |
| */ |
| public static byte[] encode(byte[] input, int flags) { |
| return encode(input, 0, input.length, flags); |
| } |
| |
| /** |
| * Base64-encode the given data and return a newly allocated |
| * byte[] with the result. |
| * |
| * @param input the data to encode |
| * @param offset the position within the input array at which to |
| * start |
| * @param len the number of bytes of input to encode |
| * @param flags controls certain features of the encoded output. |
| * Passing {@code DEFAULT} results in output that |
| * adheres to RFC 2045. |
| */ |
| public static byte[] encode(byte[] input, int offset, int len, int flags) { |
| Encoder encoder = new Encoder(flags, null); |
| |
| // Compute the exact length of the array we will produce. |
| int output_len = len / 3 * 4; |
| |
| // Account for the tail of the data and the padding bytes, if any. |
| if (encoder.do_padding) { |
| if (len % 3 > 0) { |
| output_len += 4; |
| } |
| } else { |
| switch (len % 3) { |
| case 0: break; |
| case 1: output_len += 2; break; |
| case 2: output_len += 3; break; |
| } |
| } |
| |
| // Account for the newlines, if any. |
| if (encoder.do_newline && len > 0) { |
| output_len += (((len-1) / (3 * Encoder.LINE_GROUPS)) + 1) * |
| (encoder.do_cr ? 2 : 1); |
| } |
| |
| encoder.output = new byte[output_len]; |
| encoder.process(input, offset, len, true); |
| |
| assert encoder.op == output_len; |
| |
| return encoder.output; |
| } |
| |
| /* package */ static class Encoder extends Coder { |
| /** |
| * Emit a new line every this many output tuples. Corresponds to |
| * a 76-character line length (the maximum allowable according to |
| * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>). |
| */ |
| public static final int LINE_GROUPS = 19; |
| |
| /** |
| * Lookup table for turning Base64 alphabet positions (6 bits) |
| * into output bytes. |
| */ |
| private static final byte ENCODE[] = { |
| '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', '+', '/', |
| }; |
| |
| /** |
| * Lookup table for turning Base64 alphabet positions (6 bits) |
| * into output bytes. |
| */ |
| private static final byte ENCODE_WEBSAFE[] = { |
| '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', '-', '_', |
| }; |
| |
| final private byte[] tail; |
| /* package */ int tailLen; |
| private int count; |
| |
| final public boolean do_padding; |
| final public boolean do_newline; |
| final public boolean do_cr; |
| final private byte[] alphabet; |
| |
| public Encoder(int flags, byte[] output) { |
| this.output = output; |
| |
| do_padding = (flags & NO_PADDING) == 0; |
| do_newline = (flags & NO_WRAP) == 0; |
| do_cr = (flags & CRLF) != 0; |
| alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE; |
| |
| tail = new byte[2]; |
| tailLen = 0; |
| |
| count = do_newline ? LINE_GROUPS : -1; |
| } |
| |
| /** |
| * @return an overestimate for the number of bytes {@code |
| * len} bytes could encode to. |
| */ |
| public int maxOutputSize(int len) { |
| return len * 8/5 + 10; |
| } |
| |
| public boolean process(byte[] input, int offset, int len, boolean finish) { |
| // Using local variables makes the encoder about 9% faster. |
| final byte[] alphabet = this.alphabet; |
| final byte[] output = this.output; |
| int op = 0; |
| int count = this.count; |
| |
| int p = offset; |
| len += offset; |
| int v = -1; |
| |
| // First we need to concatenate the tail of the previous call |
| // with any input bytes available now and see if we can empty |
| // the tail. |
| |
| switch (tailLen) { |
| case 0: |
| // There was no tail. |
| break; |
| |
| case 1: |
| if (p+2 <= len) { |
| // A 1-byte tail with at least 2 bytes of |
| // input available now. |
| v = ((tail[0] & 0xff) << 16) | |
| ((input[p++] & 0xff) << 8) | |
| (input[p++] & 0xff); |
| tailLen = 0; |
| }; |
| break; |
| |
| case 2: |
| if (p+1 <= len) { |
| // A 2-byte tail with at least 1 byte of input. |
| v = ((tail[0] & 0xff) << 16) | |
| ((tail[1] & 0xff) << 8) | |
| (input[p++] & 0xff); |
| tailLen = 0; |
| } |
| break; |
| } |
| |
| if (v != -1) { |
| output[op++] = alphabet[(v >> 18) & 0x3f]; |
| output[op++] = alphabet[(v >> 12) & 0x3f]; |
| output[op++] = alphabet[(v >> 6) & 0x3f]; |
| output[op++] = alphabet[v & 0x3f]; |
| if (--count == 0) { |
| if (do_cr) output[op++] = '\r'; |
| output[op++] = '\n'; |
| count = LINE_GROUPS; |
| } |
| } |
| |
| // At this point either there is no tail, or there are fewer |
| // than 3 bytes of input available. |
| |
| // The main loop, turning 3 input bytes into 4 output bytes on |
| // each iteration. |
| while (p+3 <= len) { |
| v = ((input[p] & 0xff) << 16) | |
| ((input[p+1] & 0xff) << 8) | |
| (input[p+2] & 0xff); |
| output[op] = alphabet[(v >> 18) & 0x3f]; |
| output[op+1] = alphabet[(v >> 12) & 0x3f]; |
| output[op+2] = alphabet[(v >> 6) & 0x3f]; |
| output[op+3] = alphabet[v & 0x3f]; |
| p += 3; |
| op += 4; |
| if (--count == 0) { |
| if (do_cr) output[op++] = '\r'; |
| output[op++] = '\n'; |
| count = LINE_GROUPS; |
| } |
| } |
| |
| if (finish) { |
| // Finish up the tail of the input. Note that we need to |
| // consume any bytes in tail before any bytes |
| // remaining in input; there should be at most two bytes |
| // total. |
| |
| if (p-tailLen == len-1) { |
| int t = 0; |
| v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4; |
| tailLen -= t; |
| output[op++] = alphabet[(v >> 6) & 0x3f]; |
| output[op++] = alphabet[v & 0x3f]; |
| if (do_padding) { |
| output[op++] = '='; |
| output[op++] = '='; |
| } |
| if (do_newline) { |
| if (do_cr) output[op++] = '\r'; |
| output[op++] = '\n'; |
| } |
| } else if (p-tailLen == len-2) { |
| int t = 0; |
| v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) | |
| (((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2); |
| tailLen -= t; |
| output[op++] = alphabet[(v >> 12) & 0x3f]; |
| output[op++] = alphabet[(v >> 6) & 0x3f]; |
| output[op++] = alphabet[v & 0x3f]; |
| if (do_padding) { |
| output[op++] = '='; |
| } |
| if (do_newline) { |
| if (do_cr) output[op++] = '\r'; |
| output[op++] = '\n'; |
| } |
| } else if (do_newline && op > 0 && count != LINE_GROUPS) { |
| if (do_cr) output[op++] = '\r'; |
| output[op++] = '\n'; |
| } |
| |
| assert tailLen == 0; |
| assert p == len; |
| } else { |
| // Save the leftovers in tail to be consumed on the next |
| // call to encodeInternal. |
| |
| if (p == len-1) { |
| tail[tailLen++] = input[p]; |
| } else if (p == len-2) { |
| tail[tailLen++] = input[p]; |
| tail[tailLen++] = input[p+1]; |
| } |
| } |
| |
| this.op = op; |
| this.count = count; |
| |
| return true; |
| } |
| } |
| |
| private Base64() { } // don't instantiate |
| } |