RingBuffer.cpp

/*
 * Copyright (C) 2022 CERN
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * Created on: 2022-04-07
 *     Author: Michal Mysior <mmysior> <michal.mysior@cern.ch>
 *
 */
 
#include "RingBuffer.hpp"
 
namespace smc {
namespace internal {
 
RingBuffer::RingBuffer(std::size_t size) :
    m_buff(size),
    m_ridx{0},
    m_widx{0},
    m_full{false}
{}
 
std::size_t RingBuffer::write(const char *data, std::size_t sz)
{
    for (std::size_t i = 0; i < sz; i++)
    {
        if (m_full)
            return i;
        m_buff[m_widx] = data[i];
        if (++m_widx >= m_buff.size())
            m_widx = 0;
        if (m_widx == m_ridx)
            m_full = true;
    }
    return sz;
}
 
std::size_t RingBuffer::read(char *data, std::size_t sz)
{
    for (std::size_t i = 0; i < sz; i++)
    {
        if ((m_widx == m_ridx) && !m_full)
            return i;
        m_full = false;
        data[i] = m_buff[m_ridx];
        m_ridx = (m_ridx + 1) % m_buff.size();
    }
    return sz;
}
 
std::size_t RingBuffer::bytesFree() const
{
    if (m_full)
        return 0;
    return ((m_widx >= m_ridx) ? (m_buff.size() - m_widx + m_ridx) :
                                 (m_ridx - m_widx));
}
 
} // namespace internal
} // namespace smc