1 #ifndef _DERINGBUFFER_HPP
2 #define _DERINGBUFFER_HPP
3 /*-------------------------------------------------------------------------
4 * drawElements C++ Base Library
5 * -----------------------------
6 *
7 * Copyright 2014 The Android Open Source Project
8 *
9 * Licensed under the Apache License, Version 2.0 (the "License");
10 * you may not use this file except in compliance with the License.
11 * You may obtain a copy of the License at
12 *
13 * http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 *
21 *//*!
22 * \file
23 * \brief Ring buffer template.
24 *//*--------------------------------------------------------------------*/
25
26 #include "deDefs.hpp"
27
28 namespace de
29 {
30
31 void RingBuffer_selfTest (void);
32
33 /** Ring buffer template. */
34 template <typename T>
35 class RingBuffer
36 {
37 public:
38 RingBuffer (int size);
39 ~RingBuffer (void);
40
41 void clear (void);
42 void resize (int newSize);
43
getSize(void) const44 int getSize (void) const { return m_size; }
getNumElements(void) const45 int getNumElements (void) const { return m_numElements; }
getNumFree(void) const46 int getNumFree (void) const { return m_size - m_numElements; }
47
48 void pushFront (const T& elem);
49 void pushFront (const T* elemBuf, int count);
50
51 void peekBack (T* elemBuf, int count) const;
52 T peekBack (int offset) const;
53
54 T popBack (void);
popBack(T * elemBuf,int count)55 void popBack (T* elemBuf, int count) { peekBack(elemBuf, count); popBack(count); }
56 void popBack (int count);
57
58 protected:
59 int m_numElements;
60 int m_front;
61 int m_back;
62
63 T* m_buffer;
64 int m_size;
65 };
66
67 // RingBuffer implementation.
68
69 template <typename T>
RingBuffer(int size)70 RingBuffer<T>::RingBuffer (int size)
71 : m_numElements (0)
72 , m_front (0)
73 , m_back (0)
74 , m_size (size)
75 {
76 DE_ASSERT(size > 0);
77 m_buffer = new T[m_size];
78 }
79
80 template <typename T>
~RingBuffer()81 RingBuffer<T>::~RingBuffer ()
82 {
83 delete[] m_buffer;
84 }
85
86 template <typename T>
clear(void)87 void RingBuffer<T>::clear (void)
88 {
89 m_numElements = 0;
90 m_front = 0;
91 m_back = 0;
92 }
93
94 template <typename T>
resize(int newSize)95 void RingBuffer<T>::resize (int newSize)
96 {
97 DE_ASSERT(newSize >= m_numElements);
98 T* buf = new T[newSize];
99
100 try
101 {
102 // Copy old elements.
103 for (int ndx = 0; ndx < m_numElements; ndx++)
104 buf[ndx] = m_buffer[(m_back + ndx) % m_size];
105
106 // Reset pointers.
107 m_front = m_numElements;
108 m_back = 0;
109 m_size = newSize;
110
111 DE_SWAP(T*, buf, m_buffer);
112 delete[] buf;
113 }
114 catch (...)
115 {
116 delete[] buf;
117 throw;
118 }
119 }
120
121 template <typename T>
pushFront(const T & elem)122 inline void RingBuffer<T>::pushFront (const T& elem)
123 {
124 DE_ASSERT(getNumFree() > 0);
125 m_buffer[m_front] = elem;
126 m_front = (m_front + 1) % m_size;
127 m_numElements += 1;
128 }
129
130 template <typename T>
pushFront(const T * elemBuf,int count)131 void RingBuffer<T>::pushFront (const T* elemBuf, int count)
132 {
133 DE_ASSERT(de::inRange(count, 0, getNumFree()));
134 for (int i = 0; i < count; i++)
135 m_buffer[(m_front + i) % m_size] = elemBuf[i];
136 m_front = (m_front + count) % m_size;
137 m_numElements += count;
138 }
139
140 template <typename T>
popBack()141 inline T RingBuffer<T>::popBack ()
142 {
143 DE_ASSERT(getNumElements() > 0);
144 int ndx = m_back;
145 m_back = (m_back + 1) % m_size;
146 m_numElements -= 1;
147 return m_buffer[ndx];
148 }
149
150 template <typename T>
peekBack(int offset) const151 inline T RingBuffer<T>::peekBack (int offset) const
152 {
153 DE_ASSERT(de::inBounds(offset, 0, getNumElements()));
154 return m_buffer[(m_back + offset) % m_size];
155 }
156
157 template <typename T>
peekBack(T * elemBuf,int count) const158 void RingBuffer<T>::peekBack (T* elemBuf, int count) const
159 {
160 DE_ASSERT(de::inRange(count, 0, getNumElements()));
161 for (int i = 0; i < count; i++)
162 elemBuf[i] = m_buffer[(m_back + i) % m_size];
163 }
164
165 template <typename T>
popBack(int count)166 void RingBuffer<T>::popBack (int count)
167 {
168 DE_ASSERT(de::inRange(count, 0, getNumElements()));
169 m_back = (m_back + count) % m_size;
170 m_numElements -= count;
171 }
172
173 } // de
174
175 #endif // _DERINGBUFFER_HPP
176