cache_fetch.cpp

国外开源的一个片上网络系统的源代码

/*
 *  TU Eindhoven
 *  Eindhoven, The Netherlands
 *
 *  Name            :   cache_fetch.cpp
 *
 *  Author          :   [e-mail]
 *
 *  Date            :   
 *
 *  Function        :   Cache fetch/store unit
 *
 *
 */


#include "cache_fetch.h"

void CACHE_FETCH::update_state()
{
  //busy = (next_state != IDLE);
  current_state = next_state;
  storing = n_storing;
}

void CACHE_FETCH::word_latch()
{
  if( word_clr.read() ) { word = 0; word_out = 0; }
  else if( word_inc.read() ) { word_out = word.read(); word = word.read()+1; }
}

void CACHE_FETCH::store_latch()
{
  if( storew.read() || storeb.read() || fetch.read() ){
    din_reg.write( din.read() );
    addr_reg.write( addr.read() );
  }
}

void CACHE_FETCH::logic()
{
  sc_bv<28> ma;
  sc_bv<2> off;
  sc_bv<2> byte;
  bool store_byte, store_word;

  store_byte = storeb.read();
  store_word = storew.read();

  if( current_state == IDLE ){
    ma = addr.read().range(31,4);
    off = addr.read().range(3,2);
    byte = addr.read().range(1,0);
    mem_din.write( din.read() );
  }
  else{
    ma = addr_reg.read().range(31,4);
    off = addr_reg.read().range(3,2);
    byte = addr_reg.read().range(1,0);
    mem_din.write( din_reg.read() );
  }
  
  
  if( store_word ) byte = 0;  // storing word - ignore byte number
  else if( !store_byte ) { byte=0; off = word; } // fetching word - replace word offset
  mem_addr.write( (ma,off,byte) );

  dout.write(mem_dout.read());  

  word_rdy.write(false);
  mem_ww.write(false);
  mem_wb.write(false);
  mem_r.write(false);
  busy.write(false);
  
  word_inc=false; word_clr=true;
  next_state = current_state.read();
  n_storing = 0;
  
  switch( current_state.read() )
    {
    case IDLE : 
      if( fetch.read() ){
        next_state = WAIT_MEM;
        mem_r.write(true);
        word_clr = false;
        word_inc = true;
        busy.write(true);
      }
      else if( storing.read()!=0 && !mem_rdy.read() ){
        mem_ww.write( storing.read()[0]==true );
        mem_wb.write( storing.read()[1]==true );
        next_state = IDLE;
        n_storing = storing.read();
        busy.write(true);
      }
      else if( storew.read() || storeb.read() ){
        next_state = IDLE;
        
        mem_ww.write( storew.read() );
        mem_wb.write( storeb.read() );
        sc_bv<2> s;
        s[0] = storew.read();
        s[1] = storeb.read();
        n_storing = s;
      }
      else {
        next_state = IDLE;
      }
      break;
      
    case WAIT_MEM : 
      word_clr = false;
      busy.write(true);
      n_storing = storing.read();
      
      if( mem_rdy.read() ){
        if( storing.read()==0 ) word_rdy.write(true);
        
        if( storing.read() != 0 || word.read() == 0 ){          
          mem_ww.write( false );
          mem_wb.write( false );
          mem_r.write( false );

          n_storing = 0;
          next_state = IDLE;
          word_clr = true;

          busy.write(false);
//           if( storing.read()!=0 ){ 
//             mem_ww.write( false );
//             mem_wb.write( false );
//             mem_r.write( false );
//             n_storing = 0;
//             next_state = IDLE;
//             busy.write(false);
//           }
//           else {
//             next_state = LAST_WORD;
//           }
        }
        else {
          mem_r.write( storing.read()==0 );
          mem_ww.write( storing.read()[0]==true );
          mem_wb.write( storing.read()[1]==true );
          word_inc = true;
        }
      }
      else {
        next_state = WAIT_MEM;
      }
      break;
      
   case LAST_WORD :
      word_rdy.write(true);
      busy.write(true);
      n_storing = 0;
      next_state = IDLE;
      break;
    }
}