xref: /gem5/src/systemc/ext/tlm_core/1/req_rsp/channels/fifo/circular_buffer.hh

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  more contributor license agreements.  See the NOTICE file distributed
  with this work for additional information regarding copyright ownership.
  Accellera licenses this file to you under the Apache License, Version 2.0
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#ifndef __TLM_CORE_1_REQ_RSP_CHANNELS_FIFO_CIRCULAR_BUFFER_HH__
#define __TLM_CORE_1_REQ_RSP_CHANNELS_FIFO_CIRCULAR_BUFFER_HH__

#include <iostream>

namespace tlm
{

template <typename T>
class circular_buffer
{
  public:
    explicit circular_buffer(int size=0);
    ~circular_buffer();

    void resize(int size);
    void clear();

    T read();
    void write(const T &);

    bool is_empty() const { return used() == 0; }
    bool is_full() const { return free() == 0; }

    int size() const { return m_size; }
    int used() const { return m_used; }
    int free() const { return m_free; }

    const T &read_data() const { return buf_read(m_buf, m_ri); }
    const T &
    peek_data(int i) const
    {
        return buf_read(m_buf, (m_ri + i) % size());
    }

    T &
    poke_data(int i)
    {
        return buf_read(m_buf, (m_wi + i) % size());
    }

    void debug() const;

  private:
    void increment_write_pos(int i=1);
    void increment_read_pos(int i=1);

    void init();

    // Disabled.
    circular_buffer(const circular_buffer<T> &b);
    circular_buffer<T> &operator = (const circular_buffer<T> &);

    void *buf_alloc(int size);
    void buf_free(void *&buf);
    void buf_write(void *buf, int n, const T &t);
    T &buf_read(void *buf, int n) const;
    void buf_clear(void *buf, int n);

  private:
    int m_size; // size of the buffer
    void *m_buf; // the buffer
    int m_free; // number of free spaces
    int m_used; // number of used spaces
    int m_ri; // index of next read
    int m_wi; // index of next write
};

template <typename T>
void
circular_buffer<T>::debug() const
{
    std::cout << "Buffer debug" << std::endl;
    std::cout << "Size : " << size() << std::endl;
    std::cout << "Free/Used " << free() << "/" << used() << std::endl;
    std::cout << "Indices : r/w = " << m_ri << "/" << m_wi << std::endl;

    if (is_empty()) {
        std::cout << "empty" << std::endl;
    }

    if (is_full()) {
        std::cout << "full" << std::endl;
    }

    std::cout << "Data : " << std::endl;
    for (int i = 0; i < used(); i++) {
        std::cout << peek_data( i ) << std::endl;
    }
}

template <typename T>
circular_buffer<T>::circular_buffer(int size) : m_size(size), m_buf(0)
{
    init();
}

template <typename T>
void
circular_buffer<T>::clear()
{
    for (int i = 0; i < used(); i++) {
        buf_clear(m_buf, (m_ri + i) % m_size);
    }
    m_free = m_size;
    m_used = m_ri = m_wi = 0;
}

template <typename T>
circular_buffer<T>::~circular_buffer()
{
    clear();
    buf_free(m_buf);
}

template <typename T>
void
circular_buffer<T>::resize(int size)
{
    int i;
    void *new_buf = buf_alloc(size);

    for (i = 0; i < size && i < used(); i++) {
        buf_write(new_buf, i, peek_data(i));
        buf_clear(m_buf, (m_ri + i) % m_size);
    }

    buf_free(m_buf);

    m_size = size;
    m_ri = 0;
    m_wi = i % m_size;
    m_used = i;
    m_free = m_size - m_used;

    m_buf = new_buf;
}


template <typename T>
void
circular_buffer<T>::init()
{
    if (m_size > 0) {
        m_buf = buf_alloc(m_size);
    }

    m_free = m_size;
    m_used = 0;
    m_ri = 0;
    m_wi = 0;
}

template <typename T>
T
circular_buffer<T>::read()
{
    T t = read_data();

    buf_clear(m_buf, m_ri);
    increment_read_pos();

    return t;
}

template <typename T>
void
circular_buffer<T>::write(const T &t)
{
    buf_write(m_buf, m_wi, t);
    increment_write_pos();
}

template <typename T>
void
circular_buffer<T>::increment_write_pos(int i)
{
    m_wi = (m_wi + i) % m_size;
    m_used += i;
    m_free -= i;
}

template <typename T>
void
circular_buffer<T>::increment_read_pos(int i)
{
    m_ri = (m_ri + i) % m_size;
    m_used -= i;
    m_free += i;
}

template <typename T>
inline void *
circular_buffer<T>::buf_alloc(int size)
{
    return new unsigned char [size * sizeof(T)];
}

template <typename T>
inline void
circular_buffer<T>::buf_free(void *&buf)
{
    delete [] static_cast<unsigned char *>(buf);
    buf = nullptr;
}

template <typename T>
inline void
circular_buffer<T>::buf_write(void *buf, int n, const T &t)
{
    T *p = static_cast<T *>(buf) + n;
    new (p)T(t);
}

template <typename T>
inline T &
circular_buffer<T>::buf_read(void *buf, int n) const
{
    T *p = static_cast<T *>(buf) + n;
    return *p;
}

template <typename T>
inline void
circular_buffer<T>::buf_clear(void *buf, int n)
{
    T *p = static_cast<T *>(buf) + n;
    p->~T();
}

} // namespace tlm

#endif /* __TLM_CORE_1_REQ_RSP_CHANNELS_FIFO_CIRCULAR_BUFFER_HH__ */