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s3_fifo_queue.h

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/*
 * Stone Three Foundation Class (s3fc) provides a number of utility classes.
 * Copyright (C) 2001 by Stone Three Signal Processing (Pty) Ltd.
 *
 * Authored by Stone Three Signal Processing (Pty) Ltd.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * Please see the file 'COPYING' in the source root directory.
 */

#ifndef S3_FIFO_QUEUE_H
#define S3_FIFO_QUEUE_H

#include <pthread.h>

#include <s3fc/s3_inplace_fifo_base.h>
#include <s3fc/s3_macros.h>

#if 0
#define DEBUG_STR(x) x
#include <iostream>
#else
#define DEBUG_STR(x) 
#endif


template<typename T>
class s3_fifo_queue : public s3_inplace_fifo_base<T>
{
  protected:
   unsigned int num_slots;
   pthread_mutex_t state_lock;
   bool* p_rdy;
   bool* c_rdy;
   pthread_cond_t p_rdy_changed;
   pthread_cond_t c_rdy_changed;
   unsigned int p_candidate;
   unsigned int c_candidate;
   T* slots;
  public:
   s3_fifo_queue(unsigned int n_num_slots) :
      num_slots(n_num_slots),
      p_rdy(new bool[n_num_slots]),
      c_rdy(new bool[n_num_slots]),
      p_candidate(0),
      c_candidate(0),
      slots(new T[n_num_slots])
   {
      // init flags
      for ( unsigned int i = 0; i < n_num_slots; i++ ) 
      {
    p_rdy[i] = true;
    c_rdy[i] = false;
      }
      // init threadstuff
      pthread_mutex_init(&state_lock, 0);
      pthread_cond_init(&p_rdy_changed, 0);
      pthread_cond_init(&c_rdy_changed, 0);
   }
   virtual ~s3_fifo_queue()
   {
      pthread_mutex_destroy(&state_lock);
      pthread_cond_destroy(&p_rdy_changed);
      pthread_cond_destroy(&c_rdy_changed);
      delete[] slots;
      delete[] p_rdy;
      delete[] c_rdy;
   }
   bool empty() const 
   {
      bool isempty = true;
      pthread_mutex_lock(NONCONST_MUTEXP(&state_lock));
      isempty = (c_rdy[c_candidate] == false);
      pthread_mutex_unlock(NONCONST_MUTEXP(&state_lock));
      return isempty;
   }
   bool full() const
   {
      bool isfull = true;
      pthread_mutex_lock(NONCONST_MUTEXP(&state_lock));
      isfull = (p_rdy[p_candidate] == false);
      pthread_mutex_unlock(NONCONST_MUTEXP(&state_lock));
      return isfull;
   }
   unsigned int size() const 
   {
      unsigned int cnt = 0;
      pthread_mutex_lock(NONCONST_MUTEXP(&state_lock));
      for (unsigned int i = 0; i < num_slots; i++) 
      {
    if (c_rdy[i]) cnt++;
      }
      pthread_mutex_unlock(NONCONST_MUTEXP(&state_lock));
      return cnt;
   }
  protected:
   T* open_input(bool blocking) 
   {
      T* ptr = 0;
      // set unlock handler and lock the state
      pthread_cleanup_push(s3_fifo_base<T>::unlock_mutex, &state_lock);
      pthread_mutex_lock(&state_lock);
      while (true)
      {
    if ( p_rdy[p_candidate] ) 
    {
       p_rdy[p_candidate] = false;
       ptr = &slots[p_candidate];
       p_candidate = (p_candidate+1) % num_slots;
       break;
    }
    else 
    {
       if (blocking)
       {
          // wait on p_rdy changed
          pthread_cond_wait(&p_rdy_changed, &state_lock);
       }
       else
       {
          ptr = 0;
          break;
       }
    }
      }
      DEBUG_STR( show_status("P", ptr-slots) );
      // remove handler AND unlock mutex
      pthread_cleanup_pop(0);
      pthread_mutex_unlock(&state_lock);
      // return slot data
      return ptr;
   }
  public:
   T* open_input()
   {
      return open_input(true);
   }
   T* nbl_open_input()
   {
      return open_input(false);
   }
   void close_input(const T* ptr) 
   {
      // return on null pointer
      if ( ! ptr ) 
      {
    return;
      }
      pthread_mutex_lock(&state_lock);
      p_rdy[ptr - slots] = false;
      c_rdy[ptr - slots] = true;
      pthread_cond_broadcast(&c_rdy_changed);
      s3_fifo_base<T>::notify_consumers();   // let all the consumers know
      DEBUG_STR( show_status("p", ptr-slots) );
      pthread_mutex_unlock(&state_lock);
   }
  protected:
   T* open_output(bool blocking) 
   {
      T* ptr = 0;
      // set unlock handler and lock the state
      pthread_cleanup_push(s3_fifo_base<T>::unlock_mutex, &state_lock);
      pthread_mutex_lock(&state_lock);
      // test availability
      while (true)
      {
    if ( c_rdy[c_candidate] ) 
    {
       c_rdy[c_candidate] = false;
       ptr = &slots[c_candidate];
       c_candidate = (c_candidate+1) % num_slots;
       break;
    }
    else 
    {
       if (blocking)
       {
          // wait on c_rdy changed
          pthread_cond_wait(&c_rdy_changed, &state_lock);
       }
       else
       {
          ptr = 0;
          break;
       }
    }
      }
      // we're done - give lock back
      DEBUG_STR( show_status("C", ptr-slots) );
      // remove handler AND unlock mutex
      pthread_cleanup_pop(0);
      pthread_mutex_unlock(&state_lock);
      // return slot data
      return ptr;
   }
  public:
   T* open_output()
   {
      return open_output(true);
   }
   T* nbl_open_output()
   {
      return open_output(false);
   }
   void close_output(const T* ptr) 
   {
      // return on null pointer
      if ( ! ptr ) 
      {
    return;
      }
      pthread_mutex_lock(&state_lock);
      c_rdy[ptr - slots] = false;
      p_rdy[ptr - slots] = true;
      pthread_cond_broadcast(&p_rdy_changed);
      s3_fifo_base<T>::notify_producers();   // let all the producers know
      DEBUG_STR( show_status("c", ptr-slots) );
      pthread_mutex_unlock(&state_lock);
   }
   void show_status(const char* str = 0, int slot = -1) const
   {
      std::cerr << std::endl << std::flush;
      if ( str ) std::cerr << str << std::flush;
      if ( slot != -1) std::cerr << "[" << slot << "]" << std::flush;
      std::cerr << " " << std::flush;
      for (unsigned int i = 0; i < num_slots; i++) 
      {
    if (p_rdy[i])
    {
       std::cerr << ((i == p_candidate) ? 'P' : 'p') << std::flush;
    }
    else if (c_rdy[i])
    {
       std::cerr << (( i == c_candidate) ? 'C' : 'c') << std::flush;
    }
    else 
    {
       std::cerr << '!' << std::flush;
    }
      }
   }

   unsigned int get_capacity( void ) const
   {  
      return num_slots;
   }
};

#endif

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