gr_buffer.h

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/* -*- c++ -*- */
/*
 * Copyright 2004 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio 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, or (at your option)
 * any later version.
 * 
 * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifndef INCLUDED_GR_BUFFER_H
#define INCLUDED_GR_BUFFER_H

#include <gr_runtime.h>

class gr_vmcircbuf;

gr_buffer_sptr gr_make_buffer (int nitems, size_t sizeof_item);


class gr_buffer {
 public:
  virtual ~gr_buffer ();

  int space_available () const;

  void *write_pointer ();

  void update_write_pointer (int nitems);


  void set_done (bool done)   { d_done = done; }
  bool done () const { return d_done; }

  // -------------------------------------------------------------------------

 private:

  friend class gr_buffer_reader;
  friend gr_buffer_sptr gr_make_buffer (int nitems, size_t sizeof_item);
  friend gr_buffer_reader_sptr gr_buffer_add_reader (gr_buffer_sptr buf, int history);

 protected:
  char                                 *d_base;         // base address of buffer
  unsigned int                          d_bufsize;      // in items
 private:
  gr_vmcircbuf                         *d_vmcircbuf;
  size_t                                d_sizeof_item;  // in bytes
  unsigned int                          d_write_index;  // in items [0,d_bufsize)
  std::vector<gr_buffer_reader *>       d_readers;
  bool                                  d_done;
  
  unsigned
  index_add (unsigned a, unsigned b)
  {
    unsigned s = a + b;

    if (s >= d_bufsize)
      s -= d_bufsize;

    assert (s < d_bufsize);
    return s;
  }

  unsigned
  index_sub (unsigned a, unsigned b)
  {
    int s = a - b;

    if (s < 0)
      s += d_bufsize;

    assert ((unsigned) s < d_bufsize);
    return s;
  }

  virtual bool allocate_buffer (int nitems, size_t sizeof_item);

  gr_buffer (int nitems, size_t sizeof_item);

  void drop_reader (gr_buffer_reader *reader);

};

gr_buffer_reader_sptr gr_buffer_add_reader (gr_buffer_sptr buf, int history);

long gr_buffer_ncurrently_allocated ();


// ---------------------------------------------------------------------------

class gr_buffer_reader {

 public:
  ~gr_buffer_reader ();

  int items_available () const;

  int max_possible_items_available () const { return d_buffer->d_bufsize - 1; }

  const void *read_pointer ();

  /*
   * \brief tell buffer we read \p items from it
   */
  void update_read_pointer (int nitems);

  void set_done (bool done)   { d_buffer->set_done (done); }
  bool done () const { return d_buffer->done (); }

  // -------------------------------------------------------------------------

 private:

  friend class gr_buffer;
  friend gr_buffer_reader_sptr gr_buffer_add_reader (gr_buffer_sptr buf, int history);


  gr_buffer_sptr                d_buffer;
  unsigned int                  d_read_index;   // in items [0,d->buffer.d_bufsize)

  gr_buffer_reader (gr_buffer_sptr buffer, unsigned int read_index);
};

long gr_buffer_reader_ncurrently_allocated ();


#endif /* INCLUDED_GR_BUFFER_H */

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