vm/object_start_map.cpp

   1 #include "master.hpp"
   2
   3 namespace factor
   4 {
   5
   6 object_start_map::object_start_map(cell size_, cell start_) :
   7         size(size_), start(start_)
   8 {
   9         object_start_offsets = new card[addr_to_card(size_)];
  10         object_start_offsets_end = object_start_offsets + addr_to_card(size_);
  11 }
  12
  13 object_start_map::~object_start_map()
  14 {
  15         delete[] object_start_offsets;
  16 }
  17
  18 cell object_start_map::first_object_in_card(cell card_index)
  19 {
  20         return object_start_offsets[card_index];
  21 }
  22
  23 cell object_start_map::find_object_containing_card(cell card_index)
  24 {
  25         if(card_index == 0)
  26                 return start;
  27         else
  28         {
  29                 card_index--;
  30
  31                 while(first_object_in_card(card_index) == card_starts_inside_object)
  32                 {
  33 #ifdef FACTOR_DEBUG
  34                         /* First card should start with an object */
  35                         assert(card_index > 0);
  36 #endif
  37                         card_index--;
  38                 }
  39
  40                 return start + (card_index << card_bits) + first_object_in_card(card_index);
  41         }
  42 }
  43
  44 /* we need to remember the first object allocated in the card */
  45 void object_start_map::record_object_start_offset(object *obj)
  46 {
  47         cell idx = addr_to_card((cell)obj - start);
  48         card obj_start = ((cell)obj & addr_card_mask);
  49         object_start_offsets[idx] = std::min(object_start_offsets[idx],obj_start);
  50 }
  51
  52 void object_start_map::clear_object_start_offsets()
  53 {
  54         memset(object_start_offsets,card_starts_inside_object,addr_to_card(size));
  55 }
  56
  57 }