vm/contexts.hpp

   1 namespace factor
   2 {
   3
   4 // Context object count and identifiers must be kept in sync with:
   5 //   core/kernel/kernel.factor
   6
   7 static const cell context_object_count = 10;
   8
   9 enum context_object {
  10         OBJ_NAMESTACK,
  11         OBJ_CATCHSTACK,
  12         OBJ_CONTEXT,
  13         OBJ_IN_CALLBACK_P,
  14 };
  15
  16 static const cell stack_reserved = 1024;
  17
  18 struct context {
  19
  20         // First 4 fields accessed directly by compiler. See basis/vm/vm.factor
  21
  22         /* Factor callstack pointers */
  23         stack_frame *callstack_top;
  24         stack_frame *callstack_bottom;
  25
  26         /* current datastack top pointer */
  27         cell datastack;
  28
  29         /* current retain stack top pointer */
  30         cell retainstack;
  31
  32         /* C callstack pointer */
  33         cell callstack_save;
  34
  35         segment *datastack_seg;
  36         segment *retainstack_seg;
  37         segment *callstack_seg;
  38
  39         /* context-specific special objects, accessed by context-object and
  40         set-context-object primitives */
  41         cell context_objects[context_object_count];
  42
  43         context(cell datastack_size, cell retainstack_size, cell callstack_size);
  44         ~context();
  45
  46         void reset_datastack();
  47         void reset_retainstack();
  48         void reset_callstack();
  49         void reset_context_objects();
  50         void reset();
  51         void fix_stacks();
  52         void scrub_stacks(gc_info *info, cell index);
  53
  54         cell peek()
  55         {
  56                 return *(cell *)datastack;
  57         }
  58
  59         void replace(cell tagged)
  60         {
  61                 *(cell *)datastack = tagged;
  62         }
  63
  64         cell pop()
  65         {
  66                 cell value = peek();
  67                 datastack -= sizeof(cell);
  68                 return value;
  69         }
  70
  71         void push(cell tagged)
  72         {
  73                 datastack += sizeof(cell);
  74                 replace(tagged);
  75         }
  76
  77         stack_frame *bottom_frame()
  78         {
  79                 return callstack_bottom - 1;
  80         }
  81 };
  82
  83 VM_C_API context *new_context(factor_vm *parent);
  84 VM_C_API void delete_context(factor_vm *parent, context *old_context);
  85 VM_C_API void reset_context(factor_vm *parent, context *ctx);
  86 VM_C_API cell begin_callback(factor_vm *parent, cell quot);
  87 VM_C_API void end_callback(factor_vm *parent);
  88
  89 }