MtpStringBuffer.cpp revision 7850ef999740f214a1990a9c090d3f3865d435aa 
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
17#include <string.h>
18
19#include "MtpDataPacket.h"
20#include "MtpStringBuffer.h"
21
22namespace android {
23
24MtpStringBuffer::MtpStringBuffer()
25    :   mCharCount(0),
26        mByteCount(1)
27{
28    mBuffer[0] = 0;
29}
30
31MtpStringBuffer::MtpStringBuffer(const char* src)
32    :   mCharCount(0),
33        mByteCount(1)
34{
35    set(src);
36}
37
38MtpStringBuffer::MtpStringBuffer(const MtpStringBuffer& src)
39    :   mCharCount(src.mCharCount),
40        mByteCount(src.mByteCount)
41{
42    memcpy(mBuffer, src.mBuffer, mByteCount);
43}
44
45
46MtpStringBuffer::~MtpStringBuffer() {
47}
48
49void MtpStringBuffer::set(const char* src) {
50    int length = strlen(src);
51    if (length >= sizeof(mBuffer))
52        length = sizeof(mBuffer) - 1;
53    memcpy(mBuffer, src, length);
54
55    // count the characters
56    int count = 0;
57    char ch;
58    while ((ch = *src++) != 0) {
59        if ((ch & 0x80) == 0) {
60            // single byte character
61        } else if ((ch & 0xE0) == 0xC0) {
62            // two byte character
63            if (! *src++) {
64                // last character was truncated, so ignore last byte
65                length--;
66                break;
67            }
68        } else if ((ch & 0xF0) == 0xE0) {
69            // 3 byte char
70            if (! *src++) {
71                // last character was truncated, so ignore last byte
72                length--;
73                break;
74            }
75            if (! *src++) {
76                // last character was truncated, so ignore last two bytes
77                length -= 2;
78                break;
79            }
80        }
81        count++;
82    }
83
84    mByteCount = length + 1;
85    mBuffer[length] = 0;
86    mCharCount = count;
87}
88
89void MtpStringBuffer::readFromPacket(MtpDataPacket* packet) {
90    int count = packet->getUInt8();
91    uint8_t* dest = mBuffer;
92    for (int i = 0; i < count; i++) {
93        uint16_t ch = packet->getUInt16();
94        if (ch >= 0x0800) {
95            *dest++ = (uint8_t)(0xE0 | (ch >> 12));
96            *dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
97            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
98        } else if (ch >= 0x80) {
99            *dest++ = (uint8_t)(0xC0 | (ch >> 6));
100            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
101        } else {
102            *dest++ = ch;
103        }
104    }
105    *dest++ = 0;
106    mCharCount = count;
107    mByteCount = dest - mBuffer;
108}
109
110void MtpStringBuffer::writeToPacket(MtpDataPacket* packet) const {
111    int count = mCharCount;
112    const uint8_t* src = mBuffer;
113    packet->putUInt8(count);
114
115    // expand utf8 to 16 bit chars
116    for (int i = 0; i < count; i++) {
117        uint16_t ch;
118        uint16_t ch1 = *src++;
119        if ((ch1 & 0x80) == 0) {
120            // single byte character
121            ch = ch1;
122        } else if ((ch1 & 0xE0) == 0xC0) {
123            // two byte character
124            uint16_t ch2 = *src++;
125            ch = ((ch1 & 0x1F) << 6) | (ch2 & 0x3F);
126        } else {
127            // three byte character
128            uint16_t ch2 = *src++;
129            uint16_t ch3 = *src++;
130            ch = ((ch1 & 0x0F) << 12) | ((ch2 & 0x3F) << 6) | (ch3 & 0x3F);
131        }
132        packet->putUInt16(ch);
133    }
134}
135
136}  // namespace android
137