vm/contexts.cpp

   1 #include "master.hpp"
   2
   3 namespace factor
   4 {
   5
   6 context::context(cell ds_size, cell rs_size) :
   7         callstack_top(NULL),
   8         callstack_bottom(NULL),
   9         datastack(0),
  10         retainstack(0),
  11         datastack_region(new segment(ds_size,false)),
  12         retainstack_region(new segment(rs_size,false)),
  13         next(NULL)
  14 {
  15         reset_datastack();
  16         reset_retainstack();
  17         reset_context_objects();
  18 }
  19
  20 void context::reset_datastack()
  21 {
  22         datastack = datastack_region->start - sizeof(cell);
  23 }
  24
  25 void context::reset_retainstack()
  26 {
  27         retainstack = retainstack_region->start - sizeof(cell);
  28 }
  29
  30 void context::reset_context_objects()
  31 {
  32         memset_cell(context_objects,false_object,context_object_count * sizeof(cell));
  33 }
  34
  35 context *factor_vm::alloc_context()
  36 {
  37         context *new_context;
  38
  39         if(unused_contexts)
  40         {
  41                 new_context = unused_contexts;
  42                 unused_contexts = unused_contexts->next;
  43         }
  44         else
  45                 new_context = new context(ds_size,rs_size);
  46
  47         return new_context;
  48 }
  49
  50 void factor_vm::dealloc_context(context *old_context)
  51 {
  52         old_context->next = unused_contexts;
  53         unused_contexts = old_context;
  54 }
  55
  56 /* called on entry into a compiled callback */
  57 void factor_vm::nest_stacks()
  58 {
  59         context *new_ctx = alloc_context();
  60
  61         new_ctx->callstack_bottom = (stack_frame *)-1;
  62         new_ctx->callstack_top = (stack_frame *)-1;
  63
  64         new_ctx->reset_datastack();
  65         new_ctx->reset_retainstack();
  66         new_ctx->reset_context_objects();
  67
  68         new_ctx->next = ctx;
  69         ctx = new_ctx;
  70 }
  71
  72 void nest_stacks(factor_vm *parent)
  73 {
  74         return parent->nest_stacks();
  75 }
  76
  77 /* called when leaving a compiled callback */
  78 void factor_vm::unnest_stacks()
  79 {
  80         context *old_ctx = ctx;
  81         ctx = old_ctx->next;
  82         dealloc_context(old_ctx);
  83 }
  84
  85 void unnest_stacks(factor_vm *parent)
  86 {
  87         return parent->unnest_stacks();
  88 }
  89
  90 /* called on startup */
  91 void factor_vm::init_stacks(cell ds_size_, cell rs_size_)
  92 {
  93         ds_size = ds_size_;
  94         rs_size = rs_size_;
  95         ctx = NULL;
  96         unused_contexts = NULL;
  97 }
  98
  99 void factor_vm::primitive_context_object()
 100 {
 101         fixnum n = untag_fixnum(ctx->peek());
 102         ctx->replace(ctx->context_objects[n]);
 103 }
 104
 105 void factor_vm::primitive_set_context_object()
 106 {
 107         fixnum n = untag_fixnum(ctx->pop());
 108         cell value = ctx->pop();
 109         ctx->context_objects[n] = value;
 110 }
 111
 112 bool factor_vm::stack_to_array(cell bottom, cell top)
 113 {
 114         fixnum depth = (fixnum)(top - bottom + sizeof(cell));
 115
 116         if(depth < 0)
 117                 return false;
 118         else
 119         {
 120                 array *a = allot_uninitialized_array<array>(depth / sizeof(cell));
 121                 memcpy(a + 1,(void*)bottom,depth);
 122                 ctx->push(tag<array>(a));
 123                 return true;
 124         }
 125 }
 126
 127 void factor_vm::primitive_datastack()
 128 {
 129         if(!stack_to_array(ctx->datastack_region->start,ctx->datastack))
 130                 general_error(ERROR_DS_UNDERFLOW,false_object,false_object,NULL);
 131 }
 132
 133 void factor_vm::primitive_retainstack()
 134 {
 135         if(!stack_to_array(ctx->retainstack_region->start,ctx->retainstack))
 136                 general_error(ERROR_RS_UNDERFLOW,false_object,false_object,NULL);
 137 }
 138
 139 /* returns pointer to top of stack */
 140 cell factor_vm::array_to_stack(array *array, cell bottom)
 141 {
 142         cell depth = array_capacity(array) * sizeof(cell);
 143         memcpy((void*)bottom,array + 1,depth);
 144         return bottom + depth - sizeof(cell);
 145 }
 146
 147 void factor_vm::primitive_set_datastack()
 148 {
 149         ctx->datastack = array_to_stack(untag_check<array>(ctx->pop()),ctx->datastack_region->start);
 150 }
 151
 152 void factor_vm::primitive_set_retainstack()
 153 {
 154         ctx->retainstack = array_to_stack(untag_check<array>(ctx->pop()),ctx->retainstack_region->start);
 155 }
 156
 157 /* Used to implement call( */
 158 void factor_vm::primitive_check_datastack()
 159 {
 160         fixnum out = to_fixnum(ctx->pop());
 161         fixnum in = to_fixnum(ctx->pop());
 162         fixnum height = out - in;
 163         array *saved_datastack = untag_check<array>(ctx->pop());
 164         fixnum saved_height = array_capacity(saved_datastack);
 165         fixnum current_height = (ctx->datastack - ctx->datastack_region->start + sizeof(cell)) / sizeof(cell);
 166         if(current_height - height != saved_height)
 167                 ctx->push(false_object);
 168         else
 169         {
 170                 cell *ds_bot = (cell *)ctx->datastack_region->start;
 171                 for(fixnum i = 0; i < saved_height - in; i++)
 172                 {
 173                         if(ds_bot[i] != array_nth(saved_datastack,i))
 174                         {
 175                                 ctx->push(false_object);
 176                                 return;
 177                         }
 178                 }
 179                 ctx->push(true_object);
 180         }
 181 }
 182
 183 void factor_vm::primitive_load_locals()
 184 {
 185         fixnum count = untag_fixnum(ctx->pop());
 186         memcpy((cell *)(ctx->retainstack + sizeof(cell)),
 187                 (cell *)(ctx->datastack - sizeof(cell) * (count - 1)),
 188                 sizeof(cell) * count);
 189         ctx->datastack -= sizeof(cell) * count;
 190         ctx->retainstack += sizeof(cell) * count;
 191 }
 192
 193 }