vm/contexts.hpp

   1 namespace factor {
   2
   3 // Context object count and identifiers must be kept in sync with:
   4 //   core/kernel/kernel.factor
   5 static const cell context_object_count = 4;
   6
   7 enum context_object {
   8   OBJ_NAMESTACK,
   9   OBJ_CATCHSTACK,
  10   OBJ_CONTEXT,
  11   OBJ_IN_CALLBACK_P,
  12 };
  13
  14 // When the callstack fills up (e.g by to deep recursion), a callstack
  15 // overflow error is triggered. So before continuing executing on it
  16 // in general_error(), we chop off this many bytes to have some space
  17 // to work with. Mac OSX 64 bit needs more than 8192. See issue #1419.
  18 static const cell stack_reserved = 16384;
  19
  20 struct context {
  21
  22   // First 5 fields accessed directly by compiler. See basis/vm/vm.factor
  23
  24   // Factor callstack pointers
  25   cell callstack_top;
  26   cell callstack_bottom;
  27
  28   // current datastack top pointer
  29   cell datastack;
  30
  31   // current retain stack top pointer
  32   cell retainstack;
  33
  34   // C callstack pointer
  35   cell callstack_save;
  36
  37   segment* datastack_seg;
  38   segment* retainstack_seg;
  39   segment* callstack_seg;
  40
  41   // context-specific special objects, accessed by context-object and
  42   // set-context-object primitives
  43   cell context_objects[context_object_count];
  44
  45   context(cell ds_size, cell rs_size, cell cs_size);
  46   ~context();
  47
  48   void reset_datastack();
  49   void reset_retainstack();
  50   void reset_callstack();
  51   void reset_context_objects();
  52   void reset();
  53   void fix_stacks();
  54   void fill_stack_seg(cell top_ptr, segment* seg, cell pattern);
  55   vm_error_type address_to_error(cell addr);
  56
  57   cell peek() { return *(cell*)datastack; }
  58
  59   void replace(cell tagged) { *(cell*)datastack = tagged; }
  60
  61   cell pop() {
  62     cell value = peek();
  63     datastack -= sizeof(cell);
  64     return value;
  65   }
  66
  67   void push(cell tagged) {
  68     datastack += sizeof(cell);
  69     replace(tagged);
  70   }
  71 };
  72
  73 VM_C_API context* new_context(factor_vm* parent);
  74 VM_C_API void delete_context(factor_vm* parent);
  75 VM_C_API void reset_context(factor_vm* parent);
  76 VM_C_API cell begin_callback(factor_vm* parent, cell quot);
  77 VM_C_API void end_callback(factor_vm* parent);
  78
  79 }