1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package libcore.util;
18
19import dalvik.annotation.optimization.FastNative;
20
21/**
22 * Various special-case charset conversions (for performance).
23 *
24 * @hide internal use only
25 */
26public final class CharsetUtils {
27    /**
28     * Returns a new byte array containing the bytes corresponding to the characters in the given
29     * string, encoded in US-ASCII. Unrepresentable characters are replaced by (byte) '?'.
30     */
31    @FastNative
32    public static native byte[] toAsciiBytes(String s, int offset, int length);
33
34    /**
35     * Returns a new byte array containing the bytes corresponding to the characters in the given
36     * string, encoded in ISO-8859-1. Unrepresentable characters are replaced by (byte) '?'.
37     */
38    @FastNative
39    public static native byte[] toIsoLatin1Bytes(String s, int offset, int length);
40
41    /**
42     * Returns a new byte array containing the bytes corresponding to the characters in the given
43     * string, encoded in UTF-8. All characters are representable in UTF-8.
44     */
45    @FastNative
46    public static native byte[] toUtf8Bytes(String s, int offset, int length);
47
48    /**
49     * Returns a new byte array containing the bytes corresponding to the characters in the given
50     * string, encoded in UTF-16BE. All characters are representable in UTF-16BE.
51     */
52    public static byte[] toBigEndianUtf16Bytes(String s, int offset, int length) {
53        byte[] result = new byte[length * 2];
54        int end = offset + length;
55        int resultIndex = 0;
56        for (int i = offset; i < end; ++i) {
57            char ch = s.charAt(i);
58            result[resultIndex++] = (byte) (ch >> 8);
59            result[resultIndex++] = (byte) ch;
60        }
61        return result;
62    }
63
64    /**
65     * Decodes the given US-ASCII bytes into the given char[]. Equivalent to but faster than:
66     *
67     * for (int i = 0; i < count; ++i) {
68     *     char ch = (char) (data[start++] & 0xff);
69     *     value[i] = (ch <= 0x7f) ? ch : REPLACEMENT_CHAR;
70     * }
71     */
72    @FastNative
73    public static native void asciiBytesToChars(byte[] bytes, int offset, int length, char[] chars);
74
75    /**
76     * Decodes the given ISO-8859-1 bytes into the given char[]. Equivalent to but faster than:
77     *
78     * for (int i = 0; i < count; ++i) {
79     *     value[i] = (char) (data[start++] & 0xff);
80     * }
81     */
82    @FastNative
83    public static native void isoLatin1BytesToChars(byte[] bytes, int offset, int length, char[] chars);
84
85    private CharsetUtils() {
86    }
87}
88