lib-src/gc/gcbitmap.cc

   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 welcomed 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(read crave for)
  19 // any suggestions and help from the users.
  20 //
  21 // Allen Leung (leunga@cs.nyu.edu)
  22 // 1994-1995
  23 //////////////////////////////////////////////////////////////////////////////
  24
  25 #include <iostream.h>
  26 #include <string.h>
  27 #include <assert.h>
  28 #include <AD/gc/gcbitmap.h>
  29 #include <AD/gc/gcheaps.h>
  30 #include <AD/gc/gcmacros.h>
  31
  32 // #define DEBUG_GC
  33
  34 //////////////////////////////////////////////////////////////////////////////
  35 //  Constructor
  36 //////////////////////////////////////////////////////////////////////////////
  37 GCBitMap::GCBitMap()
  38    : lowest_addr(0), highest_addr(0),
  39      bitmap(0), bitmap_bot(0), bitmap_top(0), bitmap_core(0),
  40      bitmap_size(0) {}
  41
  42 //////////////////////////////////////////////////////////////////////////////
  43 //  Destructor
  44 //////////////////////////////////////////////////////////////////////////////
  45 GCBitMap::~GCBitMap() { release(); }
  46
  47 //////////////////////////////////////////////////////////////////////////////
  48 //  Method to clear the entire bitmap
  49 //////////////////////////////////////////////////////////////////////////////
  50 void GCBitMap::clear()
  51 {  memset(bitmap_bot, 0, bitmap_size);
  52 }
  53
  54 //////////////////////////////////////////////////////////////////////////////
  55 //  Method to release all the memory of a bitmap
  56 //////////////////////////////////////////////////////////////////////////////
  57 void GCBitMap::release()
  58 {
  59    if (bitmap_core) {
  60       HM::deallocate_pages_on_boundaries(bitmap_core, bitmap_size);
  61       lowest_addr  = 0;
  62       highest_addr = 0;
  63       bitmap       = 0;
  64       bitmap_bot   = 0;
  65       bitmap_top   = 0;
  66       bitmap_core  = 0;
  67       bitmap_size  = 0;
  68    }
  69 }
  70
  71 //////////////////////////////////////////////////////////////////////////////
  72 //  Method to grow the bitmap.
  73 //////////////////////////////////////////////////////////////////////////////
  74 void GCBitMap::grow (void * low, void * high)
  75 {
  76    // roundup to page size
  77    void * real_low  = GC_TRUNC_PAGE_ADDR(low);
  78    void * real_high = GC_ROUNDUP_PAGE_ADDR((Byte*)high + 1);
  79
  80    // compute new address boundaries
  81    void * new_low   = (real_low < lowest_addr || lowest_addr == 0)
  82                         ? real_low : lowest_addr;
  83    void * new_high  = real_high > highest_addr ? real_high : highest_addr;
  84
  85    // Check whether the boundaries have changed.
  86    // If so, expand the bitmap
  87    if (new_low != lowest_addr || new_high != highest_addr) {
  88       size_t new_size        = ((Byte*)new_high - (Byte*)new_low) /
  89                                    (8 * GC_ALIGNMENT);
  90       new_size = GC_ROUNDUP_PAGE_SIZE(new_size);
  91       void * new_bitmap_core;
  92       Glob * new_bitmap_bot  =
  93          (Glob*)HM::allocate_pages_on_boundaries(new_size, new_bitmap_core);
  94       size_t shift           =
  95          lowest_addr == 0 ? 0 :
  96               (((Byte*)lowest_addr - (Byte*)new_low) /
  97                        (8 * GC_ALIGNMENT * sizeof(Glob)));
  98
  99       // copy old bitmap to new
 100       memcpy(new_bitmap_bot + shift, bitmap_bot, bitmap_size);
 101
 102       // clean up old bitmap and delete it
 103       HM::deallocate_pages_on_boundaries(bitmap_core, bitmap_size);
 104
 105       // readjust bitmap pointers and offsets
 106       lowest_addr  = new_low;
 107       highest_addr = new_high;
 108       bitmap_size  = new_size;
 109       bitmap_core  = new_bitmap_core;
 110       bitmap_bot   = new_bitmap_bot;
 111       bitmap       = new_bitmap_bot -
 112                         ((size_t)new_low / (sizeof(Glob) * 8 * GC_ALIGNMENT));
 113       bitmap_top   = bitmap_bot + new_size / sizeof(Glob);
 114
 115 #ifdef DEBUG_GC
 116       cerr << "[ New bitmap at " << (void*)bitmap_bot
 117            << " ... " << (void*)bitmap_top << " ]\n";
 118 #endif
 119    }
 120 }