MtpStringBuffer.cpp revision b14e588bec4d5e39e61b020b5b575f2ce555d316 
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#define LOG_TAG "MtpStringBuffer"
18
19#include <string.h>
20
21#include "MtpDataPacket.h"
22#include "MtpStringBuffer.h"
23
24namespace android {
25
26MtpStringBuffer::MtpStringBuffer()
27    :   mCharCount(0),
28        mByteCount(1)
29{
30    mBuffer[0] = 0;
31}
32
33MtpStringBuffer::MtpStringBuffer(const char* src)
34    :   mCharCount(0),
35        mByteCount(1)
36{
37    set(src);
38}
39
40MtpStringBuffer::MtpStringBuffer(const MtpStringBuffer& src)
41    :   mCharCount(src.mCharCount),
42        mByteCount(src.mByteCount)
43{
44    memcpy(mBuffer, src.mBuffer, mByteCount);
45}
46
47
48MtpStringBuffer::~MtpStringBuffer() {
49}
50
51void MtpStringBuffer::set(const char* src) {
52    int length = strlen(src);
53    if (length >= sizeof(mBuffer))
54        length = sizeof(mBuffer) - 1;
55    memcpy(mBuffer, src, length);
56
57    // count the characters
58    int count = 0;
59    char ch;
60    while ((ch = *src++) != 0) {
61        if ((ch & 0x80) == 0) {
62            // single byte character
63        } else if ((ch & 0xE0) == 0xC0) {
64            // two byte character
65            if (! *src++) {
66                // last character was truncated, so ignore last byte
67                length--;
68                break;
69            }
70        } else if ((ch & 0xF0) == 0xE0) {
71            // 3 byte char
72            if (! *src++) {
73                // last character was truncated, so ignore last byte
74                length--;
75                break;
76            }
77            if (! *src++) {
78                // last character was truncated, so ignore last two bytes
79                length -= 2;
80                break;
81            }
82        }
83        count++;
84    }
85
86    mByteCount = length + 1;
87    mBuffer[length] = 0;
88    mCharCount = count;
89}
90
91void MtpStringBuffer::readFromPacket(MtpDataPacket* packet) {
92    int count = packet->getUInt8();
93    uint8_t* dest = mBuffer;
94    for (int i = 0; i < count; i++) {
95        uint16_t ch = packet->getUInt16();
96        if (ch >= 0x0800) {
97            *dest++ = (uint8_t)(0xE0 | (ch >> 12));
98            *dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
99            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
100        } else if (ch >= 0x80) {
101            *dest++ = (uint8_t)(0xC0 | (ch >> 6));
102            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
103        } else {
104            *dest++ = ch;
105        }
106    }
107    *dest++ = 0;
108    mCharCount = count;
109    mByteCount = dest - mBuffer;
110}
111
112void MtpStringBuffer::writeToPacket(MtpDataPacket* packet) const {
113    int count = mCharCount;
114    const uint8_t* src = mBuffer;
115    packet->putUInt8(count);
116
117    // expand utf8 to 16 bit chars
118    for (int i = 0; i < count; i++) {
119        uint16_t ch;
120        uint16_t ch1 = *src++;
121        if ((ch1 & 0x80) == 0) {
122            // single byte character
123            ch = ch1;
124        } else if ((ch1 & 0xE0) == 0xC0) {
125            // two byte character
126            uint16_t ch2 = *src++;
127            ch = ((ch1 & 0x1F) << 6) | (ch2 & 0x3F);
128        } else {
129            // three byte character
130            uint16_t ch2 = *src++;
131            uint16_t ch3 = *src++;
132            ch = ((ch1 & 0x0F) << 12) | ((ch2 & 0x3F) << 6) | (ch3 & 0x3F);
133        }
134        packet->putUInt16(ch);
135    }
136}
137
138}  // namespace android
139