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         clear_object_start_offsets();
  12 }
  13
  14 object_start_map::~object_start_map()
  15 {
  16         delete[] object_start_offsets;
  17 }
  18
  19 cell object_start_map::first_object_in_card(cell card_index)
  20 {
  21         return object_start_offsets[card_index];
  22 }
  23
  24 cell object_start_map::find_object_containing_card(cell card_index)
  25 {
  26         if(card_index == 0)
  27                 return start;
  28         else
  29         {
  30                 card_index--;
  31
  32                 while(first_object_in_card(card_index) == card_starts_inside_object)
  33                 {
  34 #ifdef FACTOR_DEBUG
  35                         /* First card should start with an object */
  36                         assert(card_index > 0);
  37 #endif
  38                         card_index--;
  39                 }
  40
  41                 return start + (card_index << card_bits) + first_object_in_card(card_index);
  42         }
  43 }
  44
  45 /* we need to remember the first object allocated in the card */
  46 void object_start_map::record_object_start_offset(object *obj)
  47 {
  48         cell idx = addr_to_card((cell)obj - start);
  49         card obj_start = ((cell)obj & addr_card_mask);
  50         object_start_offsets[idx] = std::min(object_start_offsets[idx],obj_start);
  51 }
  52
  53 void object_start_map::clear_object_start_offsets()
  54 {
  55         memset(object_start_offsets,card_starts_inside_object,addr_to_card(size));
  56 }
  57
  58 void object_start_map::update_card_for_sweep(cell index, u16 mask)
  59 {
  60         cell offset = object_start_offsets[index];
  61         if(offset != card_starts_inside_object)
  62         {
  63                 mask >>= (offset / data_alignment);
  64
  65                 if(mask == 0)
  66                 {
  67                         /* The rest of the block after the old object start is free */
  68                         object_start_offsets[index] = card_starts_inside_object;
  69                 }
  70                 else
  71                 {
  72                         /* Move the object start forward if necessary */
  73                         object_start_offsets[index] = (card)(offset + (rightmost_set_bit(mask) * data_alignment));
  74                 }
  75         }
  76 }
  77
  78 void object_start_map::update_for_sweep(mark_bits<object> *state)
  79 {
  80         for(cell index = 0; index < state->bits_size; index++)
  81         {
  82                 cell mask = state->marked[index];
  83 #ifdef FACTOR_64
  84                 update_card_for_sweep(index * 4,      mask        & 0xffff);
  85                 update_card_for_sweep(index * 4 + 1, (mask >> 16) & 0xffff);
  86                 update_card_for_sweep(index * 4 + 2, (mask >> 32) & 0xffff);
  87                 update_card_for_sweep(index * 4 + 3, (mask >> 48) & 0xffff);
  88 #else
  89                 update_card_for_sweep(index * 2,      mask        & 0xffff);
  90                 update_card_for_sweep(index * 2 + 1, (mask >> 16) & 0xffff);
  91 #endif
  92         }
  93 }
  94
  95 }