/* 
 * delayqueue.h
 *
 * Copyright (c) 2009 by Tor M. Aamodt, Wilson W. L. Fung, Ali Bakhoda,
 * Ivan Sham, Henry Tran and the University of British Columbia
 * Vancouver, BC  V6T 1Z4
 * All Rights Reserved.
 * 
 * THIS IS A LEGAL DOCUMENT BY DOWNLOADING GPGPU-SIM, YOU ARE AGREEING TO THESE
 * TERMS AND CONDITIONS.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * NOTE: The files libcuda/cuda_runtime_api.c and src/cuda-sim/cuda-math.h
 * are derived from the CUDA Toolset available from http://www.nvidia.com/cuda
 * (property of NVIDIA).  The files benchmarks/BlackScholes/ and 
 * benchmarks/template/ are derived from the CUDA SDK available from 
 * http://www.nvidia.com/cuda (also property of NVIDIA).  The files from 
 * src/intersim/ are derived from Booksim (a simulator provided with the 
 * textbook "Principles and Practices of Interconnection Networks" available 
 * from http://cva.stanford.edu/books/ppin/). As such, those files are bound by 
 * the corresponding legal terms and conditions set forth separately (original 
 * copyright notices are left in files from these sources and where we have 
 * modified a file our copyright notice appears before the original copyright 
 * notice).  
 * 
 * Using this version of GPGPU-Sim requires a complete installation of CUDA 
 * which is distributed seperately by NVIDIA under separate terms and 
 * conditions.  To use this version of GPGPU-Sim with OpenCL requires a
 * recent version of NVIDIA's drivers which support OpenCL.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. Neither the name of the University of British Columbia nor the names of
 * its contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * 4. This version of GPGPU-SIM is distributed freely for non-commercial use only.  
 *  
 * 5. No nonprofit user may place any restrictions on the use of this software,
 * including as modified by the user, by any other authorized user.
 * 
 * 6. GPGPU-SIM was developed primarily by Tor M. Aamodt, Wilson W. L. Fung, 
 * Ali Bakhoda, George L. Yuan, at the University of British Columbia, 
 * Vancouver, BC V6T 1Z4
 */

#include <stdio.h>
#include <assert.h>
#include <stdlib.h>

#ifndef DELAYQUEUE_H
#define DELAYQUEUE_H

#include "../intersim/statwraper.h"
#include "gpu-misc.h"

template <class T>
struct fifo_data {
   T *m_data;
   fifo_data *m_next;
   unsigned long long  push_time; //for stat collection
};

template <class T> 
class fifo_pipeline {
public:
   fifo_pipeline(const char* nm, unsigned int minlen, unsigned int maxlen, unsigned long long current_time ) 
   {
      m_name = nm;
      m_min_len = minlen;
      m_max_len = maxlen;
      m_length = 0;
      m_n_element = 0;
      m_head = NULL;
      m_tail = NULL;
      for (unsigned i=0;i<m_min_len;i++) 
         push(NULL,current_time);
      m_lat_stat = StatCreate(m_name,1,32);  
   }

   ~fifo_pipeline() 
   {
      while (m_head) {
         m_tail = m_head;
         m_head = m_head->m_next;
         delete m_tail;
      }
   }

   void push(T* data, unsigned long long current_time ) 
   {
      if (m_max_len) assert(m_length < m_max_len);
      if (m_head) {
         if (m_tail->m_data || m_length < m_min_len) {
            m_tail->m_next = new fifo_data<T>();
            m_tail = m_tail->m_next;
            m_length++;
            m_n_element++;
         }
      } else {
         m_head = m_tail = new fifo_data<T>();
         m_length++;
         m_n_element++;
      }
      m_tail->m_next = NULL;
      m_tail->m_data = data;
      m_tail->push_time = current_time;
   }

   T* pop( unsigned long long current_time ) 
   {
      fifo_data<T>* next;
      T* data;
      if (m_head) {
        next = m_head->m_next;
        data = m_head->m_data;
        StatAddSample(m_lat_stat, LOGB2 (current_time - m_head->push_time));
        if ( m_head == m_tail ) {
           assert( next == NULL );
           m_tail = NULL;     
        }
        delete m_head;
        m_head = next;
        m_length--;
        if (m_length == 0) {
           assert( m_head == NULL );
           m_tail = m_head;
        }
        m_n_element--; 
         if (m_min_len && m_length < m_min_len) {
            push(NULL,current_time);
            m_n_element--; // uncount NULL elements inserted to create delays
         }
      } else {
         data = NULL;
      }
      return data;
   }

   T* top() 
   {
      if (m_head) {
         return m_head->m_data;
      } else {
         return NULL;
      }
   }

   void set_min_length(unsigned int new_min_len, unsigned long long current_time) 
   {
      if (new_min_len == m_min_len) return;
   
      if (new_min_len > m_min_len) {
         m_min_len = new_min_len;
         while (m_length < m_min_len) {
            push(NULL,current_time);
            m_n_element--; // uncount NULL elements inserted to create delays
         }
      } else {
         // in this branch imply that the original min_len is larger then 0
         // ie. head != 0
         assert(m_head);
         m_min_len = new_min_len;
         while ((m_length > m_min_len) && (m_tail->m_data == 0)) {
            fifo_data<T> *iter;
            iter = m_head;
            while (iter && (iter->m_next != m_tail))
               iter = iter->m_next;
            if (!iter) {
               // there is only one node, and that node is empty
               assert(m_head->m_data == 0);
               pop(current_time);
            } else {
               // there are more than one node, and tail node is empty
               assert(iter->m_next == m_tail);
               delete m_tail;
               m_tail = iter;
               m_tail->m_next = 0;
               m_length--;
            }
         }
      }
   }

   bool full() const { return (m_max_len && m_length >= m_max_len); }
   bool empty() const { return m_head == NULL; }
   unsigned get_n_element() const { return m_n_element; }
   unsigned get_length() const { return m_length; }
   unsigned get_max_len() const { return m_max_len; }
   void* get_lat_stat() { return m_lat_stat; }

   void print() const
   {
      fifo_data<T>* ddp = m_head;
      printf("%s(%d): ", m_name, m_length);
      while (ddp) {
         printf("%p ", ddp->m_data);
         ddp = ddp->m_next;
      }
      printf("\n");
   }

private:
   const char* m_name;

   unsigned int m_min_len;
   unsigned int m_max_len;
   unsigned int m_length;
   unsigned int m_n_element;

   fifo_data<T> *m_head;
   fifo_data<T> *m_tail;

   void* m_lat_stat; //a pointer to latency stats distribution structure
};

#endif