include/AD/memory/freelist.h

   1 //////////////////////////////////////////////////////////////////////////////
   2 // NOTICE:
   3 //
   4 // ADLib, Prop and their related set of tools and documentation are in the
   5 // public domain.   The author(s) of this software reserve no copyrights on
   6 // the source code and any code generated using the tools.  You are encouraged
   7 // to use ADLib and Prop to develop software, in both academic and commercial
   8 // settings, and are free to incorporate any part of ADLib and Prop into
   9 // your programs.
  10 //
  11 // Although you are under no obligation to do so, we strongly recommend that
  12 // you give away all software developed using our tools.
  13 //
  14 // We also ask that credit be given to us when ADLib and/or Prop are used in
  15 // your programs, and that this notice be preserved intact in all the source
  16 // code.
  17 //
  18 // This software is still under development and we welcome any suggestions
  19 // and help from the users.
  20 //
  21 // Allen Leung
  22 // 1994
  23 //////////////////////////////////////////////////////////////////////////////
  24
  25 #ifndef free_lists_h
  26 #define free_lists_h
  27
  28 //////////////////////////////////////////////////////////////////////////////
  29 //  This trick is borrowed from the LEDA library.
  30 //////////////////////////////////////////////////////////////////////////////
  31
  32 #include <new.h>
  33
  34 #define Max_free_list_cell_size 1023 // we keep free lists up to 1023 bytes.
  35
  36 struct Free_list_cell { Free_list_cell * next; };
  37 extern Free_list_cell * free_lists[];
  38
  39 #define Use_free_list_manager(type)                                        \
  40    void * operator new (int)                                               \
  41       {  Free_list_cell * cell = free_lists[sizeof(type)];                 \
  42          if (cell) { free_lists[sizeof(type)] = cell->next; return cell; } \
  43          else return ::new char [sizeof(type)];                            \
  44       }                                                                    \
  45    void operator delete(void * t)                                          \
  46       {  Free_list_cell * cell = (Free_list_cell*)t;                       \
  47          cell->next = free_lists[sizeof(type)];                            \
  48          free_lists[sizeof(type)] = cell;                                  \
  49       }                                                                    \
  50
  51 #define Implement_free_list_manager(max_size) \
  52    Free_list_cell * free_lists[max_size];
  53
  54 #endif