xref: /gem5/ext/systemc/src/sysc/communication/sc_mutex.cpp

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  Licensed to Accellera Systems Initiative Inc. (Accellera) under one or
  more contributor license agreements.  See the NOTICE file distributed
  with this work for additional information regarding copyright ownership.
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  (the "License"); you may not use this file except in compliance with the
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  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  implied.  See the License for the specific language governing
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 *****************************************************************************/

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

  sc_mutex.cpp -- The sc_mutex primitive channel class.

  Original Author: Martin Janssen, Synopsys, Inc., 2001-05-21

  CHANGE LOG IS AT THE END OF THE FILE
 *****************************************************************************/

#include "sysc/communication/sc_mutex.h"
#include "sysc/kernel/sc_simcontext.h"

namespace sc_core {

// ----------------------------------------------------------------------------
//  CLASS : sc_mutex
//
//  The sc_mutex primitive channel class.
// ----------------------------------------------------------------------------

// constructors

sc_mutex::sc_mutex()
: sc_object( sc_gen_unique_name( "mutex" ) ),
  m_owner( 0 ),
  m_free( (std::string(SC_KERNEL_EVENT_PREFIX)+"_free_event").c_str() )
{}

sc_mutex::sc_mutex( const char* name_ )
: sc_object( name_ ),
  m_owner( 0 ),
  m_free( (std::string(SC_KERNEL_EVENT_PREFIX)+"_free_event").c_str() )
{}


// destructor

sc_mutex::~sc_mutex()
{}

// interface methods

// blocks until mutex could be locked

int
sc_mutex::lock()
{
    if ( m_owner == sc_get_current_process_b()) return 0;
    while( in_use() ) {
	sc_core::wait( m_free, sc_get_curr_simcontext() );
    }
    m_owner = sc_get_current_process_b();
    return 0;
}


// returns -1 if mutex could not be locked

int
sc_mutex::trylock()
{
    if ( m_owner == sc_get_current_process_b()) return 0;
    if( in_use() ) {
	return -1;
    }
    m_owner = sc_get_current_process_b();
    return 0;
}


// returns -1 if mutex was not locked by caller

int
sc_mutex::unlock()
{
    if( m_owner != sc_get_current_process_b() ) {
	return -1;
    }
    m_owner = 0;
    m_free.notify();
    return 0;
}

} // namespace sc_core

// $Log: sc_mutex.cpp,v $
// Revision 1.7  2011/08/26 20:45:40  acg
//  Andy Goodrich: moved the modification log to the end of the file to
//  eliminate source line number skew when check-ins are done.
//
// Revision 1.6  2011/03/28 13:02:29  acg
//  Andy Goodrich: removed sc_event in sc_mutex class from the object
//  hierarchy since it is considered a "kernel" event.
//
// Revision 1.5  2011/02/18 20:23:45  acg
//  Andy Goodrich: Copyright update.
//
// Revision 1.4  2010/11/02 16:31:01  acg
//  Andy Goodrich: changed object derivation to use sc_object rather than
//  sc_prim_channel as the parent class.
//
// Revision 1.3  2008/11/13 15:29:46  acg
//  David C. Black, ESLX, Inc: lock & trylock now allow owner to apply
//  lock more than once without incident. Previous behavior locked up the
//  owning process.
//
// Revision 1.2  2008/05/20 16:46:18  acg
//  Andy Goodrich: added checks for multiple writers.
//
// Revision 1.1.1.1  2006/12/15 20:20:04  acg
// SystemC 2.3
//
// Revision 1.4  2006/03/21 00:00:27  acg
//   Andy Goodrich: changed name of sc_get_current_process_base() to be
//   sc_get_current_process_b() since its returning an sc_process_b instance.
//
// Revision 1.3  2006/01/13 18:47:42  acg
// Added $Log command so that CVS comments are reproduced in the source.
//

// Taf!