SerialBuffer.cpp

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Digital Voice Modem - Hotspot Firmware
 * GPLv2 Open Source. Use is subject to license terms.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 *  Copyright (C) 2015,2016 Jonathan Naylor, G4KLX
 *  Serial FIFO Control Copyright (C) 2015 by James McLaughlin, KI6ZUM
 *  Copyright (C) 2022 Bryan Biedenkapp, N2PLL
 *
 */
#include "SerialBuffer.h"

// ---------------------------------------------------------------------------
//  Public Class Members
// ---------------------------------------------------------------------------

/* Initializes a new instance of the SerialBuffer class. */

SerialBuffer::SerialBuffer(uint16_t length) :
    m_length(length),
    m_buffer(NULL),
    m_head(0U),
    m_tail(0U),
    m_full(false)
{
    m_buffer = new uint8_t[length];
}

/* Finalizes a instance of the SerialBuffer class. */

SerialBuffer::~SerialBuffer()
{
    delete[] m_buffer;
}

/* Helper to get how much space the ring buffer has for samples. */

uint16_t SerialBuffer::getSpace() const
{
    uint16_t n = 0U;

    if (m_tail == m_head)
        n = m_full ? 0U : m_length;
    else if (m_tail < m_head)
        n = m_length - m_head + m_tail;
    else
        n = m_tail - m_head;

    if (n > m_length)
        n = 0U;

    return n;
}

/* */

uint16_t SerialBuffer::getData() const
{
    if (m_tail == m_head)
        return m_full ? m_length : 0U;
    else if (m_tail < m_head)
        return m_head - m_tail;
    else
        return m_length - m_tail + m_head;
}

/* Helper to reset data values to defaults. */

void SerialBuffer::reset()
{
    m_head = 0U;
    m_tail = 0U;
    m_full = false;
}

/* Helper to reset and reinitialize data values to defaults. */

void SerialBuffer::reinitialize(uint16_t length)
{
    reset();

    m_length = length;

    delete[] m_buffer;
    m_buffer = new uint8_t[length];
}

/* */

bool SerialBuffer::put(uint8_t c)
{
    if (m_full)
        return false;

    m_buffer[m_head] = c;

    m_head++;
    if (m_head >= m_length)
        m_head = 0U;

    if (m_head == m_tail)
        m_full = true;

    return true;
}

/* */

uint8_t SerialBuffer::peek() const
{
    return m_buffer[m_tail];
}

/* */

uint8_t SerialBuffer::get()
{
    uint8_t value = m_buffer[m_tail];

    m_full = false;

    m_tail++;
    if (m_tail >= m_length)
        m_tail = 0U;

    return value;
}