Implement buffering of visualizer samples read from the fifo

src/utility/sample_buffer.cpp

@@ -0,0 +1,93 @@
+/***************************************************************************
+ *   Copyright (C) 2008-2017 by Andrzej Rybczak                            *
+ *   electricityispower@gmail.com                                          *
+ *                                                                         *
+ *   This program 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.                                   *
+ *                                                                         *
+ *   This program 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 more 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.              *
+ ***************************************************************************/
+
+#include <stdexcept>
+
+#include "utility/sample_buffer.h"
+
+void SampleBuffer::put(SampleBuffer::Iterator begin, SampleBuffer::Iterator end)
+{
+	size_t elems = end - begin;
+	if (elems > m_buffer.size())
+		throw std::out_of_range("Size of the buffer is smaller than the amount of elements");
+
+	size_t free_elems = m_buffer.size() - m_offset;
+	if (elems > free_elems)
+	{
+		size_t to_remove = elems - free_elems;
+		std::copy(m_buffer.begin() + to_remove, m_buffer.end() - free_elems,
+		          m_buffer.begin());
+		m_offset -= to_remove;
+	}
+	std::copy(begin, end, m_buffer.begin() + m_offset);
+	m_offset += elems;
+}
+
+size_t SampleBuffer::move(size_t elems, std::vector<int16_t> &dest)
+{
+	if (m_offset == 0)
+		return 0;
+
+	// If the amount of requested samples is bigger than available, return only
+	// available.
+	if (elems > m_offset)
+		elems = m_offset;
+
+	if (elems >= dest.size())
+	{
+		// If dest is smaller than the available amount of samples, discard the
+		// ones that come first.
+		size_t elems_lost = elems - dest.size();
+		std::copy(m_buffer.begin() + elems_lost, m_buffer.begin() + elems, dest.begin());
+	}
+	else
+	{
+		// Copy samples to the destination buffer.
+		std::copy(dest.begin() + elems, dest.end(), dest.begin());
+		std::copy(m_buffer.begin(), m_buffer.begin() + elems, dest.end() - elems);
+	}
+
+	// Remove them from the internal buffer.
+	std::copy(m_buffer.begin() + elems, m_buffer.begin() + m_offset, m_buffer.begin());
+	m_offset -= elems;
+
+	return elems;
+}
+
+void SampleBuffer::resize(size_t n)
+{
+	m_buffer.resize(n);
+	clear();
+}
+
+void SampleBuffer::clear()
+{
+	m_offset = 0;
+}
+
+size_t SampleBuffer::size() const
+{
+	return m_offset;
+}
+
+const std::vector<int16_t> &SampleBuffer::buffer() const
+{
+	return m_buffer;
+}