tlm_fifo.h

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/*****************************************************************************

  The following code is derived, directly or indirectly, from the SystemC
  source code Copyright (c) 1996-2014 by all Contributors.
  All Rights reserved.

  The contents of this file are subject to the restrictions and limitations
  set forth in the SystemC Open Source License (the "License");
  You may not use this file except in compliance with such restrictions and
  limitations. You may obtain instructions on how to receive a copy of the
  License at http://www.accellera.org/. Software distributed by Contributors
  under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
  ANY KIND, either express or implied. See the License for the specific
  language governing rights and limitations under the License.

 *****************************************************************************/

#ifndef __TLM_FIFO_H__
#define __TLM_FIFO_H__

//
// This implements put, get and peek
//
// It also implements 0 and infinite size fifos - but the size
// zero fifos aren't rendezvous like zero length fifos, they simply are both
// full and empty at the same time.
//
// The size can be dynamically changed using the resize interface
//
// To get an infinite fifo use a -ve size in the constructor.
// The absolute value of the size is taken as the starting size of the
// actual physical buffer.
//

//#include <systemc>

#include "tlm_core/tlm_1/tlm_req_rsp/tlm_1_interfaces/tlm_fifo_ifs.h"
#include "tlm_core/tlm_1/tlm_req_rsp/tlm_channels/tlm_fifo/circular_buffer.h"

namespace tlm {

template <typename T>
class tlm_fifo :
  public virtual tlm_fifo_get_if<T>,
  public virtual tlm_fifo_put_if<T>,
  public sc_core::sc_prim_channel
{
public:

    // constructors

    explicit tlm_fifo( int size_ = 1 )
      : sc_core::sc_prim_channel( sc_core::sc_gen_unique_name( "fifo" ) ) {

      init( size_ );

    }

    explicit tlm_fifo( const char* name_, int size_ = 1 )
      : sc_core::sc_prim_channel( name_ ) {

      init( size_ );

    }

    // destructor

    virtual ~tlm_fifo() {}

    // tlm get interface

    T get( tlm_tag<T> * = 0 );

    bool nb_get( T& );
    bool nb_can_get( tlm_tag<T> * = 0 ) const;
    const sc_core::sc_event &ok_to_get( tlm_tag<T> * = 0 ) const {
      return m_data_written_event;
    }

    // tlm peek interface

    T peek( tlm_tag<T> * = 0 ) const;

    bool nb_peek( T& ) const;
    bool nb_can_peek( tlm_tag<T> * = 0 ) const;
    const sc_core::sc_event &ok_to_peek( tlm_tag<T> * = 0 ) const {
      return m_data_written_event;
    }

    // tlm put interface

    void put( const T& );

    bool nb_put( const T& );
    bool nb_can_put( tlm_tag<T> * = 0 ) const;

    const sc_core::sc_event& ok_to_put( tlm_tag<T> * = 0 ) const {
      return m_data_read_event;
    }

    // resize if

    void nb_expand( unsigned int n = 1 );
    void nb_unbound( unsigned int n = 16 );

    bool nb_reduce( unsigned int n = 1 );
    bool nb_bound( unsigned int n );

    // debug interface

    bool nb_peek( T & , int n ) const;
    bool nb_poke( const T & , int n = 0 );

    int used() const {
      return m_num_readable - m_num_read;
    }

    int size() const {
      return m_size;
    }

    void debug() const {

      if( is_empty() ) std::cout << "empty" << std::endl;
      if( is_full() ) std::cout << "full" << std::endl;

      std::cout << "size " << size() << " - " << used() << " used "
                << std::endl;
      std::cout << "readable " << m_num_readable
                << std::endl;
      std::cout << "written/read " << m_num_written << "/" << m_num_read
                << std::endl;

    }

    // support functions

    static const char* const kind_string;

    const char* kind() const
        { return kind_string; }


protected:
    sc_core::sc_event &read_event( tlm_tag<T> * = 0 ) {
      return m_data_read_event;
    }

protected:

    void update();

    // support methods

    void init( int );

protected:

    circular_buffer<T> buffer;

    int m_size;                  // logical size of fifo

    int m_num_readable;          // #samples readable
    int m_num_read;          // #samples read during this delta cycle
    int m_num_written;           // #samples written during this delta cycle
    bool m_expand;               // has an expand occurred during this delta cycle ?
    int m_num_read_no_notify;    // #samples read without notify during this delta cycle

    sc_core::sc_event m_data_read_event;
    sc_core::sc_event m_data_written_event;

private:

    // disabled
    tlm_fifo( const tlm_fifo<T>& );
    tlm_fifo& operator = ( const tlm_fifo<T>& );

    //
    // use nb_can_get() and nb_can_put() rather than the following two
    // private functions
    //

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

    bool is_full() const {
      //return size() == m_num_readable + m_num_written; // Old buggy code
      if( size() < 0 )
        return false;
      else
        return size() <= m_num_readable + m_num_written;
    }

};

template <typename T>
const char* const tlm_fifo<T>::kind_string = "tlm_fifo";


/******************************************************************
//
// init and update
//
******************************************************************/

template< typename T >
inline
void
tlm_fifo<T>::init( int size_ ) {

  if( size_ > 0 ) {
    buffer.resize( size_ );
  }

  else if( size_ < 0 ) {
    buffer.resize( -size_ );
  }

  else {
    buffer.resize( 16 );
  }

  m_size = size_;
  m_num_readable = 0;
  m_num_read = 0;
  m_num_written = 0;
  m_expand = false;
  m_num_read_no_notify = false;

}

template < typename T>
inline
void
tlm_fifo<T>::update()
{
    if( m_num_read > m_num_read_no_notify || m_expand ) {
  m_data_read_event.notify( sc_core::SC_ZERO_TIME );
    }

    if( m_num_written > 0 ) {
  m_data_written_event.notify( sc_core::SC_ZERO_TIME );
    }

    m_expand = false;
    m_num_read = 0;
    m_num_written = 0;
    m_num_readable = buffer.used();
    m_num_read_no_notify = 0;

}

} // namespace tlm

#include "tlm_core/tlm_1/tlm_req_rsp/tlm_channels/tlm_fifo/tlm_fifo_put_get.h"
#include "tlm_core/tlm_1/tlm_req_rsp/tlm_channels/tlm_fifo/tlm_fifo_peek.h"
#include "tlm_core/tlm_1/tlm_req_rsp/tlm_channels/tlm_fifo/tlm_fifo_resize.h"

#endif