xref: /gem5/ext/systemc/src/sysc/utils/sc_pq.cpp

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

  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.
  Accellera licenses this file to you under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with the
  License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  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
  permissions and limitations under the License.

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

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

  sc_pq.cpp - Simple heap implementation of priority queue.

  Original Author: Stan Y. Liao, Synopsys, Inc.

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

// $Log: sc_pq.cpp,v $
// Revision 1.4  2011/08/26 20:46:18  acg
//  Andy Goodrich: moved the modification log to the end of the file to
//  eliminate source line number skew when check-ins are done.
//

#include "sysc/utils/sc_pq.h"

namespace sc_core {

sc_ppq_base::sc_ppq_base( int sz, int (*cmp)( const void*, const void* ) )
    : m_heap(0), m_size_alloc( sz ), m_heap_size( 0 ), m_compar( cmp )
{
    // m_size_alloc must be at least 2, otherwise resizing doesn't work
    if( m_size_alloc < 2 ) {
	m_size_alloc = 2;
    }
    // allocate
    m_heap = new void*[m_size_alloc + 1];
    // initialize
    for( int i = 0; i < m_size_alloc; ++ i ) {
	m_heap[i] = 0;
    }
}

sc_ppq_base::~sc_ppq_base()
{
    delete[] m_heap;
}

void*
sc_ppq_base::extract_top()
{
    assert( m_heap_size > 0 );
    void* topelem = m_heap[1];
    m_heap[1] = m_heap[m_heap_size];
    m_heap_size --;
    heapify( 1 );
    return topelem;
}

void
sc_ppq_base::insert( void* elem )
{
    m_heap_size ++;
    int i = m_heap_size;

    // resize the heap in case there's not enough memory
    if( m_heap_size > m_size_alloc ) {
        m_size_alloc += m_size_alloc / 2;
        void** new_heap = new void*[m_size_alloc + 1];
        for( int j = 1; j < m_heap_size; ++ j ) {
            new_heap[j] = m_heap[j];
        }
        delete[] m_heap;
        m_heap = new_heap;
    }

    while( (i > 1) && (m_compar( m_heap[parent( i )], elem ) < 0) ) {
        m_heap[i] = m_heap[parent( i )];
        i = parent( i );
    }
    m_heap[i] = elem;
}

void
sc_ppq_base::heapify( int i )
{
    int l;
    while( l = left( i ), l <= m_heap_size ) {
        int largest = (m_compar( m_heap[l], m_heap[i] ) > 0) ? l : i;

        int r = right( i );
        if( (r <= m_heap_size) &&
	    (m_compar( m_heap[r], m_heap[largest] ) > 0) ) {
            largest = r;
	}

        if( largest != i ) {
            void* tmp = m_heap[i];
            m_heap[i] = m_heap[largest];
            m_heap[largest] = tmp;
            i = largest;
        } else {
            break;
	}
    }
}

} // namespace sc_core

// Revision 1.3  2011/08/24 22:05:56  acg
//  Torsten Maehne: initialization changes to remove warnings.
//
// Revision 1.2  2011/02/18 20:38:44  acg
//  Andy Goodrich: Updated Copyright notice.
//
// Revision 1.1.1.1  2006/12/15 20:20:06  acg
// SystemC 2.3
//
// Revision 1.3  2006/01/13 18:53:11  acg
// Andy Goodrich: Added $Log command so that CVS comments are reproduced in
// the source.

// taf