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RingBuffer.hpp

00001 /* This file is part of Raul.
00002  * Copyright (C) 2007-2009 David Robillard <http://drobilla.net>
00003  *
00004  * Raul is free software; you can redistribute it and/or modify it under the
00005  * terms of the GNU General Public License as published by the Free Software
00006  * Foundation; either version 2 of the License, or (at your option) any later
00007  * version.
00008  *
00009  * Raul is distributed in the hope that it will be useful, but WITHOUT ANY
00010  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
00011  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for details.
00012  *
00013  * You should have received a copy of the GNU General Public License along
00014  * with this program; if not, write to the Free Software Foundation, Inc.,
00015  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
00016  */
00017 
00018 #ifndef RAUL_RING_BUFFER_HPP
00019 #define RAUL_RING_BUFFER_HPP
00020 
00021 #include <cassert>
00022 #include <cstring>
00023 #include <cstdlib>
00024 #include <iostream>
00025 #include <glib.h>
00026 #include "raul/log.hpp"
00027 
00028 namespace Raul {
00029 
00030 
00035 template <typename T>
00036 class RingBuffer {
00037 public:
00040     RingBuffer(size_t size)
00041         : _size(size)
00042         , _buf(static_cast<char*>(malloc(size)))
00043     {
00044         reset();
00045         assert(read_space() == 0);
00046         assert(write_space() == size - 1);
00047     }
00048 
00049     virtual ~RingBuffer() {
00050         free(_buf);
00051     }
00052 
00056     void reset() {
00057         g_atomic_int_set(&_write_ptr, 0);
00058         g_atomic_int_set(&_read_ptr, 0);
00059     }
00060 
00061     size_t write_space() const {
00062         const size_t w = g_atomic_int_get(&_write_ptr);
00063         const size_t r = g_atomic_int_get(&_read_ptr);
00064 
00065         if (w > r) {
00066             return ((r - w + _size) % _size) - 1;
00067         } else if (w < r) {
00068             return (r - w) - 1;
00069         } else {
00070             return _size - 1;
00071         }
00072     }
00073 
00074     size_t read_space() const {
00075         const size_t w = g_atomic_int_get(&_write_ptr);
00076         const size_t r = g_atomic_int_get(&_read_ptr);
00077 
00078         if (w > r) {
00079             return w - r;
00080         } else {
00081             return (w - r + _size) % _size;
00082         }
00083     }
00084 
00085     size_t capacity() const { return _size; }
00086 
00087     size_t peek(size_t size, T* dst);
00088     bool   full_peek(size_t size, T* dst);
00089 
00090     size_t read(size_t size, T* dst);
00091     bool   full_read(size_t size, T* dst);
00092 
00093     bool   skip(size_t size);
00094 
00095     void   write(size_t size, const T* src);
00096 
00097 protected:
00098     mutable int _write_ptr;
00099     mutable int _read_ptr;
00100 
00101     size_t _size; 
00102     char*  _buf;  
00103 };
00104 
00105 
00112 template<typename T>
00113 size_t
00114 RingBuffer<T>::peek(size_t size, T* dst)
00115 {
00116     const size_t priv_read_ptr = g_atomic_int_get(&_read_ptr);
00117 
00118     const size_t read_size = (priv_read_ptr + size < _size)
00119             ? size
00120             : _size - priv_read_ptr;
00121 
00122     memcpy(dst, &_buf[priv_read_ptr], read_size);
00123 
00124     return read_size;
00125 }
00126 
00127 
00128 template<typename T>
00129 bool
00130 RingBuffer<T>::full_peek(size_t size, T* dst)
00131 {
00132     if (read_space() < size) {
00133         return false;
00134     }
00135 
00136     const size_t read_size = peek(size, dst);
00137 
00138     if (read_size < size) {
00139         peek(size - read_size, dst + read_size);
00140     }
00141 
00142     return true;
00143 }
00144 
00145 
00152 template<typename T>
00153 size_t
00154 RingBuffer<T>::read(size_t size, T* dst)
00155 {
00156     const size_t priv_read_ptr = g_atomic_int_get(&_read_ptr);
00157 
00158     const size_t read_size = (priv_read_ptr + size < _size)
00159             ? size
00160             : _size - priv_read_ptr;
00161 
00162     memcpy(dst, &_buf[priv_read_ptr], read_size);
00163 
00164     g_atomic_int_set(&_read_ptr, (priv_read_ptr + read_size) % _size);
00165 
00166     return read_size;
00167 }
00168 
00169 
00170 template<typename T>
00171 bool
00172 RingBuffer<T>::full_read(size_t size, T* dst)
00173 {
00174     if (read_space() < size) {
00175         return false;
00176     }
00177 
00178     const size_t read_size = read(size, dst);
00179 
00180     if (read_size < size) {
00181         read(size - read_size, dst + read_size);
00182     }
00183 
00184     return true;
00185 }
00186 
00187 
00188 template<typename T>
00189 bool
00190 RingBuffer<T>::skip(size_t size)
00191 {
00192     if (read_space() < size) {
00193         warn << "Attempt to skip past end of RingBuffer" << std::endl;
00194         return false;
00195     }
00196 
00197     const size_t priv_read_ptr = g_atomic_int_get(&_read_ptr);
00198     g_atomic_int_set(&_read_ptr, (priv_read_ptr + size) % _size);
00199 
00200     return true;
00201 }
00202 
00203 
00204 template<typename T>
00205 inline void
00206 RingBuffer<T>::write(size_t size, const T* src)
00207 {
00208     const size_t priv_write_ptr = g_atomic_int_get(&_write_ptr);
00209 
00210     if (priv_write_ptr + size <= _size) {
00211         memcpy(&_buf[priv_write_ptr], src, size);
00212         g_atomic_int_set(&_write_ptr, (priv_write_ptr + size) % _size);
00213     } else {
00214         const size_t this_size = _size - priv_write_ptr;
00215         assert(this_size < size);
00216         assert(priv_write_ptr + this_size <= _size);
00217         memcpy(&_buf[priv_write_ptr], src, this_size);
00218         memcpy(&_buf[0], src+this_size, size - this_size);
00219         g_atomic_int_set(&_write_ptr, size - this_size);
00220     }
00221 }
00222 
00223 
00224 } // namespace Raul
00225 
00226 #endif // RAUL_RING_BUFFER_HPP
00227 

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