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/*
 *  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.
 */

package java.nio.charset;

import java.io.UTFDataFormatException;
import java.nio.ByteOrder;
import libcore.io.Memory;
import libcore.io.SizeOf;

/**
 * @hide internal use only
 */
public class ModifiedUtf8 {
    /**
     * Decodes a byte array containing modified UTF-8 bytes into a string.
     *
     * 

Note that although this method decodes the (supposedly impossible) zero byte to U+0000, * that's what the RI does too. */ public static String decode(byte[] in, char[] out, int offset, int utfSize) throws UTFDataFormatException { int count = 0, s = 0, a; while (count < utfSize) { if ((out[s] = (char) in[offset + count++]) < '\u0080') { s++; } else if (((a = out[s]) & 0xe0) == 0xc0) { if (count >= utfSize) { throw new UTFDataFormatException("bad second byte at " + count); } int b = in[offset + count++]; if ((b & 0xC0) != 0x80) { throw new UTFDataFormatException("bad second byte at " + (count - 1)); } out[s++] = (char) (((a & 0x1F) << 6) | (b & 0x3F)); } else if ((a & 0xf0) == 0xe0) { if (count + 1 >= utfSize) { throw new UTFDataFormatException("bad third byte at " + (count + 1)); } int b = in[offset + count++]; int c = in[offset + count++]; if (((b & 0xC0) != 0x80) || ((c & 0xC0) != 0x80)) { throw new UTFDataFormatException("bad second or third byte at " + (count - 2)); } out[s++] = (char) (((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F)); } else { throw new UTFDataFormatException("bad byte at " + (count - 1)); } } return new String(out, 0, s); } /** * Returns the number of bytes the modified UTF-8 representation of 's' would take. Note * that this is just the space for the bytes representing the characters, not the length * which precedes those bytes, because different callers represent the length differently, * as two, four, or even eight bytes. If {@code shortLength} is true, we'll throw an * exception if the string is too long for its length to be represented by a short. */ public static long countBytes(String s, boolean shortLength) throws UTFDataFormatException { long result = 0; final int length = s.length(); for (int i = 0; i < length; ++i) { char ch = s.charAt(i); if (ch != 0 && ch <= 127) { // U+0000 uses two bytes. ++result; } else if (ch <= 2047) { result += 2; } else { result += 3; } if (shortLength && result > 65535) { throw new UTFDataFormatException("String more than 65535 UTF bytes long"); } } return result; } /** * Encodes the modified UTF-8 bytes corresponding to string {@code s} into the * byte array {@code dst}, starting at the given {@code offset}. */ public static void encode(byte[] dst, int offset, String s) { final int length = s.length(); for (int i = 0; i < length; i++) { char ch = s.charAt(i); if (ch != 0 && ch <= 127) { // U+0000 uses two bytes. dst[offset++] = (byte) ch; } else if (ch <= 2047) { dst[offset++] = (byte) (0xc0 | (0x1f & (ch >> 6))); dst[offset++] = (byte) (0x80 | (0x3f & ch)); } else { dst[offset++] = (byte) (0xe0 | (0x0f & (ch >> 12))); dst[offset++] = (byte) (0x80 | (0x3f & (ch >> 6))); dst[offset++] = (byte) (0x80 | (0x3f & ch)); } } } /** * Returns an array containing the modified UTF-8 form of {@code s}, using a * big-endian 16-bit length. Throws UTFDataFormatException if {@code s} is too long * for a two-byte length. */ public static byte[] encode(String s) throws UTFDataFormatException { int utfCount = (int) ModifiedUtf8.countBytes(s, true); byte[] result = new byte[SizeOf.SHORT + utfCount]; Memory.pokeShort(result, 0, (short) utfCount, ByteOrder.BIG_ENDIAN); ModifiedUtf8.encode(result, SizeOf.SHORT, s); return result; } private ModifiedUtf8() { } }





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