vm/contexts.hpp

   1 namespace factor
   2 {
   3
   4 static const cell context_object_count = 10;
   5
   6 enum context_object {
   7         OBJ_NAMESTACK,
   8         OBJ_CATCHSTACK,
   9 };
  10
  11 struct context {
  12
  13         // First 4 fields accessed directly by compiler. See basis/vm/vm.factor
  14
  15         /* Factor callstack pointers */
  16         stack_frame *callstack_top;
  17         stack_frame *callstack_bottom;
  18
  19         /* current datastack top pointer */
  20         cell datastack;
  21
  22         /* current retain stack top pointer */
  23         cell retainstack;
  24
  25         /* C callstack pointer */
  26         cell callstack_save;
  27
  28         /* context-specific special objects, accessed by context-object and
  29         set-context-object primitives */
  30         cell context_objects[context_object_count];
  31
  32         segment *datastack_seg;
  33         segment *retainstack_seg;
  34         segment *callstack_seg;
  35
  36         context(cell datastack_size, cell retainstack_size, cell callstack_size);
  37         ~context();
  38
  39         void reset_datastack();
  40         void reset_retainstack();
  41         void reset_callstack();
  42         void reset_context_objects();
  43         void reset();
  44
  45         cell peek()
  46         {
  47                 return *(cell *)datastack;
  48         }
  49
  50         void replace(cell tagged)
  51         {
  52                 *(cell *)datastack = tagged;
  53         }
  54
  55         cell pop()
  56         {
  57                 cell value = peek();
  58                 datastack -= sizeof(cell);
  59                 return value;
  60         }
  61
  62         void push(cell tagged)
  63         {
  64                 datastack += sizeof(cell);
  65                 replace(tagged);
  66         }
  67
  68         static const cell stack_reserved = (64 * sizeof(cell));
  69
  70         void fix_stacks()
  71         {
  72                 if(datastack + sizeof(cell) < datastack_seg->start
  73                         || datastack + stack_reserved >= datastack_seg->end)
  74                         reset_datastack();
  75
  76                 if(retainstack + sizeof(cell) < retainstack_seg->start
  77                         || retainstack + stack_reserved >= retainstack_seg->end)
  78                         reset_retainstack();
  79         }
  80 };
  81
  82 VM_C_API void begin_callback(factor_vm *vm);
  83 VM_C_API void end_callback(factor_vm *vm);
  84
  85 }