scfx_mant.cc

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/*****************************************************************************
 
  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.
 
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  Description of Modification:
 
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// $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