scfx_mant.cc

Go to the documentation of this file.

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

  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.

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

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

  scfx_mant.cpp -

  Original Author: Robert Graulich, Synopsys, Inc.
                   Martin Janssen,  Synopsys, Inc.

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

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

  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
  changes you are making here.

      Name, Affiliation, Date:
  Description of Modification:

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


// $Log: scfx_mant.cpp,v $
// Revision 1.1.1.1  2006/12/15 20:20:04  acg
// SystemC 2.3
//
// Revision 1.3  2006/01/13 18:53:58  acg
// Andy Goodrich: added $Log command so that CVS comments are reproduced in
// the source.
//

#include "systemc/ext/dt/fx/scfx_mant.hh"

namespace sc_dt
{

// ----------------------------------------------------------------------------
//  word memory management
// ----------------------------------------------------------------------------

class word_list // Entry in free_words bucket.
{
  public:
    word_list *m_next_p;
};

static inline unsigned
next_pow2_index(std::size_t size)
{
    unsigned index = scfx_find_msb(size);
    // If this was a power of 2 we are one bucket too low.
    if (~(UINT64_ONE << index) & size)
        index++;
    // If this is a 64-bit machine and we are using 32-bit words go down
    // one slot size, as all the slots are 2x in size.
    if (index != 0 && (sizeof(word_list) != sizeof(word))) {
        index -= 1;
    }
    return index;
}

static word_list *free_words[32] = { 0 };

word *
scfx_mant::alloc_word(std::size_t size)
{
    const int ALLOC_SIZE = 128;

    unsigned slot_index = next_pow2_index(size);
    unsigned alloc_size = (UINT64_ONE << slot_index);

    word_list*& slot = free_words[slot_index];

    if (!slot) {
        slot = new word_list[ALLOC_SIZE * alloc_size];
        unsigned i;
        for (i = 0; i < alloc_size * (ALLOC_SIZE - 1) ; i += alloc_size) {
            slot[i].m_next_p = &slot[i + alloc_size];
        }
        slot[i].m_next_p = 0;
    }

    word *result = (word *)slot;
    free_words[slot_index] = slot[0].m_next_p;
    return result;
}

void
scfx_mant::free_word(word *array, std::size_t size)
{
    if (array && size) {
        int slot_index = next_pow2_index(size);
        word_list *wl_p = (word_list *)array;

        wl_p->m_next_p = free_words[slot_index];
        free_words[slot_index] = wl_p;
    }
}

} // namespace sc_dt