MtpStringBuffer.cpp revision 16864bae0f51c32c456da2c43adf7a057c0c4882 
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
22
23MtpStringBuffer::MtpStringBuffer()
24    :   mCharCount(0),
25        mByteCount(1)
26{
27    mBuffer[0] = 0;
28}
29
30MtpStringBuffer::MtpStringBuffer(const char* src)
31    :   mCharCount(0),
32        mByteCount(1)
33{
34    set(src);
35}
36
37MtpStringBuffer::MtpStringBuffer(const MtpStringBuffer& src)
38    :   mCharCount(src.mCharCount),
39        mByteCount(src.mByteCount)
40{
41    memcpy(mBuffer, src.mBuffer, mByteCount);
42}
43
44
45MtpStringBuffer::~MtpStringBuffer() {
46}
47
48void MtpStringBuffer::set(const char* src) {
49    int length = strlen(src);
50    if (length >= sizeof(mBuffer))
51        length = sizeof(mBuffer) - 1;
52    memcpy(mBuffer, src, length);
53
54    // count the characters
55    int count = 0;
56    char ch;
57    while ((ch = *src++) != 0) {
58        if ((ch & 0x80) == 0) {
59            // single byte character
60        } else if ((ch & 0xE0) == 0xC0) {
61            // two byte character
62            if (! *src++) {
63                // last character was truncated, so ignore last byte
64                length--;
65                break;
66            }
67        } else if ((ch & 0xF0) == 0xE0) {
68            // 3 byte char
69            if (! *src++) {
70                // last character was truncated, so ignore last byte
71                length--;
72                break;
73            }
74            if (! *src++) {
75                // last character was truncated, so ignore last two bytes
76                length -= 2;
77                break;
78            }
79        }
80        count++;
81    }
82
83    mByteCount = length + 1;
84    mBuffer[length] = 0;
85    mCharCount = count;
86}
87
88void MtpStringBuffer::readFromPacket(MtpDataPacket* packet) {
89    int count = packet->getUInt8();
90    uint8_t* dest = mBuffer;
91    for (int i = 0; i < count; i++) {
92        uint16_t ch = packet->getUInt16();
93        if (ch >= 0x0800) {
94            *dest++ = (uint8_t)(0xE0 | (ch >> 12));
95            *dest++ = (uint8_t)(0x80 | ((ch >> 6) & 0x3F));
96            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
97        } else if (ch >= 0x80) {
98            *dest++ = (uint8_t)(0xC0 | (ch >> 6));
99            *dest++ = (uint8_t)(0x80 | (ch & 0x3F));
100        } else {
101            *dest++ = ch;
102        }
103    }
104    *dest++ = 0;
105    mCharCount = count;
106    mByteCount = dest - mBuffer;
107}
108
109void MtpStringBuffer::writeToPacket(MtpDataPacket* packet) const {
110    int count = mCharCount;
111    const uint8_t* src = mBuffer;
112    packet->putUInt8(count);
113
114    // expand utf8 to 16 bit chars
115    for (int i = 0; i < count; i++) {
116        uint16_t ch;
117        uint16_t ch1 = *src++;
118        if ((ch1 & 0x80) == 0) {
119            // single byte character
120            ch = ch1;
121        } else if ((ch1 & 0xE0) == 0xC0) {
122            // two byte character
123            uint16_t ch2 = *src++;
124            ch = ((ch1 & 0x1F) << 6) | (ch2 & 0x3F);
125        } else {
126            // three byte character
127            uint16_t ch2 = *src++;
128            uint16_t ch3 = *src++;
129            ch = ((ch1 & 0x0F) << 12) | ((ch2 & 0x3F) << 6) | (ch3 & 0x3F);
130        }
131        packet->putUInt16(ch);
132    }
133}
134