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author | David Robillard <d@drobilla.net> | 2007-03-31 01:40:11 +0000 |
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committer | David Robillard <d@drobilla.net> | 2007-03-31 01:40:11 +0000 |
commit | 423cbc959a04b6d54365b943b22936ec6b2a4b62 (patch) | |
tree | 9e349380384b0e8b5532a6507f32e21cfe20a5b9 /raul/RingBuffer.h | |
parent | 9e81a81484aa0142f0c02cf066c41bd2d2c84eea (diff) | |
download | raul-423cbc959a04b6d54365b943b22936ec6b2a4b62.tar.gz raul-423cbc959a04b6d54365b943b22936ec6b2a4b62.tar.bz2 raul-423cbc959a04b6d54365b943b22936ec6b2a4b62.zip |
Added RingBuffer and MIDIRingBuffer classes/tests.
git-svn-id: http://svn.drobilla.net/lad/raul@382 a436a847-0d15-0410-975c-d299462d15a1
Diffstat (limited to 'raul/RingBuffer.h')
-rw-r--r-- | raul/RingBuffer.h | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/raul/RingBuffer.h b/raul/RingBuffer.h new file mode 100644 index 0000000..beaf957 --- /dev/null +++ b/raul/RingBuffer.h @@ -0,0 +1,163 @@ +/* This file is part of Raul. + * Copyright (C) 2007 Dave Robillard <http://drobilla.net> + * + * Raul is free software; you can redistribute it and/or modify it under the + * terms of the GNU General Public License as published by the Free Software + * Foundation; either version 2 of the License, or (at your option) any later + * version. + * + * Raul is distributed in the hope that it will be useful, but WITHOUT ANY + * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS + * FOR A PARTICULAR PURPOSE. See the GNU General Public License for details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef RAUL__RING_BUFFER_H +#define RAUL__RING_BUFFER_H + +#include <cassert> +#include <glib.h> + +namespace Raul { + + +/** A lock-free RingBuffer. + * Read/Write realtime safe. + * Single-reader Single-writer thread safe. + */ +template <typename T> +class RingBuffer { +public: + + /** @param size Size in bytes. + */ + RingBuffer(size_t size) + : _size(size) + , _buf(new T[size]) + { + reset(); + assert(read_space() == 0); + assert(write_space() == size - 1); + } + + virtual ~RingBuffer() { + delete[] _buf; + } + + /** Reset(empty) the ringbuffer. + * NOT thread safe. + */ + void reset() { + g_atomic_int_set(&_write_ptr, 0); + g_atomic_int_set(&_read_ptr, 0); + } + + size_t write_space() const { + + const size_t w = g_atomic_int_get(&_write_ptr); + const size_t r = g_atomic_int_get(&_read_ptr); + + if (w > r) { + return ((r - w + _size) % _size) - 1; + } else if(w < r) { + return (r - w) - 1; + } else { + return _size - 1; + } + } + + size_t read_space() const { + + const size_t w = g_atomic_int_get(&_write_ptr); + const size_t r = g_atomic_int_get(&_read_ptr); + + if (w > r) { + return w - r; + } else { + return (w - r + _size) % _size; + } + } + + size_t capacity() const { return _size; } + + size_t read(size_t size, T* dst); + void write(size_t size, const T* src); + + bool full_read(size_t size, T* dst); + +protected: + mutable gint _write_ptr; + mutable gint _read_ptr; + + size_t _size; ///< Size (capacity) in bytes + T* _buf; ///< size, event, size, event... +}; + + +/** Read from the ringbuffer. + * + * Note that a full read may not be done if the data wraps around. + * Caller must check return value and call again if necessary, or use the + * full_read method which does this automatically. + */ +template<typename T> +size_t +RingBuffer<T>::read(size_t size, T* dst) +{ + const size_t priv_read_ptr = g_atomic_int_get(&_read_ptr); + + const size_t read_size = (priv_read_ptr + size < _size) + ? size + : _size - priv_read_ptr; + + memcpy(dst, &_buf[priv_read_ptr], read_size); + + g_atomic_int_set(&_read_ptr, (priv_read_ptr + read_size) % _size); + + return read_size; +} + + +template<typename T> +inline void +RingBuffer<T>::write(size_t size, const T* src) +{ + const size_t priv_write_ptr = g_atomic_int_get(&_write_ptr); + + if (priv_write_ptr + size <= _size) { + memcpy(&_buf[priv_write_ptr], src, size); + g_atomic_int_set(&_write_ptr, (priv_write_ptr + size) % _size); + } else { + const size_t this_size = _size - priv_write_ptr; + assert(this_size < size); + assert(priv_write_ptr + this_size <= _size); + memcpy(&_buf[priv_write_ptr], src, this_size); + memcpy(&_buf[0], src+this_size, size - this_size); + g_atomic_int_set(&_write_ptr, size - this_size); + } +} + + +template<typename T> +bool +RingBuffer<T>::full_read(size_t size, T* dst) +{ + if (read_space() < size) + return false; + + const size_t read_size = read(size, dst); + + if (read_size < size) + read(size - read_size, dst + read_size); + + return true; +} + + +} // namespace Raul + +#endif // RAUL_RING_BUFFER_H + |