1/****************************************************************************
2**
3** Copyright (C) 2016 The Qt Company Ltd.
4** Contact: https://www.qt.io/licensing/
5**
6** This file is part of the QtBluetooth module of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:LGPL$
9** Commercial License Usage
10** Licensees holding valid commercial Qt licenses may use this file in
11** accordance with the commercial license agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and The Qt Company. For licensing terms
14** and conditions see https://www.qt.io/terms-conditions. For further
15** information use the contact form at https://www.qt.io/contact-us.
16**
17** GNU Lesser General Public License Usage
18** Alternatively, this file may be used under the terms of the GNU Lesser
19** General Public License version 3 as published by the Free Software
20** Foundation and appearing in the file LICENSE.LGPL3 included in the
21** packaging of this file. Please review the following information to
22** ensure the GNU Lesser General Public License version 3 requirements
23** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
24**
25** GNU General Public License Usage
26** Alternatively, this file may be used under the terms of the GNU
27** General Public License version 2.0 or (at your option) the GNU General
28** Public license version 3 or any later version approved by the KDE Free
29** Qt Foundation. The licenses are as published by the Free Software
30** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
31** included in the packaging of this file. Please review the following
32** information to ensure the GNU General Public License requirements will
33** be met: https://www.gnu.org/licenses/gpl-2.0.html and
34** https://www.gnu.org/licenses/gpl-3.0.html.
35**
36** $QT_END_LICENSE$
37**
38****************************************************************************/
39
40#ifndef QPRIVATELINEARBUFFER_P_H
41#define QPRIVATELINEARBUFFER_P_H
42
43//
44// W A R N I N G
45// -------------
46//
47// This file is not part of the Qt API. It exists purely as an
48// implementation detail. This header file may change from version to
49// version without notice, or even be removed.
50//
51// We mean it.
52//
53
54// This is QIODevice's read buffer, optimised for read(), isEmpty() and getChar()
55class QPrivateLinearBuffer
56{
57public:
58 QPrivateLinearBuffer() : len(0), first(0), buf(0), capacity(0) {
59 }
60 ~QPrivateLinearBuffer() {
61 delete [] buf;
62 }
63 void clear() {
64 first = buf;
65 len = 0;
66 }
67 int size() const {
68 return len;
69 }
70 bool isEmpty() const {
71 return len == 0;
72 }
73 void skip(int n) {
74 if (n >= len) {
75 clear();
76 } else {
77 len -= n;
78 first += n;
79 }
80 }
81 int getChar() {
82 if (len == 0)
83 return -1;
84 int ch = uchar(*first);
85 len--;
86 first++;
87 return ch;
88 }
89 int read(char* target, int size) {
90 int r = qMin(size, len);
91 memcpy(target, first, r);
92 len -= r;
93 first += r;
94 return r;
95 }
96 char* reserve(int size) {
97 makeSpace(size + len, freeSpaceAtEnd);
98 char* writePtr = first + len;
99 len += size;
100 return writePtr;
101 }
102 void chop(int size) {
103 if (size >= len) {
104 clear();
105 } else {
106 len -= size;
107 }
108 }
109 QByteArray readAll() {
110 char* f = first;
111 int l = len;
112 clear();
113 return QByteArray(f, l);
114 }
115 int readLine(char* target, int size) {
116 int r = qMin(size, len);
117 char* eol = static_cast<char*>(memchr(first, '\n', r));
118 if (eol)
119 r = 1+(eol-first);
120 memcpy(target, first, r);
121 len -= r;
122 first += r;
123 return int(r);
124 }
125 bool canReadLine() const {
126 return memchr(first, '\n', len);
127 }
128 void ungetChar(char c) {
129 if (first == buf) {
130 // underflow, the existing valid data needs to move to the end of the (potentially bigger) buffer
131 makeSpace(len+1, freeSpaceAtStart);
132 }
133 first--;
134 len++;
135 *first = c;
136 }
137 void ungetBlock(const char* block, int size) {
138 if ((first - buf) < size) {
139 // underflow, the existing valid data needs to move to the end of the (potentially bigger) buffer
140 makeSpace(len + size, freeSpaceAtStart);
141 }
142 first -= size;
143 len += size;
144 memcpy(first, block, size);
145 }
146
147private:
148 enum FreeSpacePos {freeSpaceAtStart, freeSpaceAtEnd};
149 void makeSpace(size_t required, FreeSpacePos where) {
150 size_t newCapacity = qMax(capacity, size_t(QPRIVATELINEARBUFFER_BUFFERSIZE));
151 while (newCapacity < required)
152 newCapacity *= 2;
153 const int moveOffset = (where == freeSpaceAtEnd) ? 0 : int(newCapacity) - len;
154 if (newCapacity > capacity) {
155 // allocate more space
156 char* newBuf = new char[newCapacity];
157 memmove(newBuf + moveOffset, first, len);
158 delete [] buf;
159 buf = newBuf;
160 capacity = newCapacity;
161 } else {
162 // shift any existing data to make space
163 memmove(buf + moveOffset, first, len);
164 }
165 first = buf + moveOffset;
166 }
167
168private:
169 // length of the unread data
170 int len;
171 // start of the unread data
172 char* first;
173 // the allocated buffer
174 char* buf;
175 // allocated buffer size
176 size_t capacity;
177};
178
179#endif // QPRIVATELINEARBUFFER_P_H
180

source code of qtconnectivity/src/bluetooth/qprivatelinearbuffer_p.h