vm/callbacks.cpp

   1 #include "master.hpp"
   2
   3 namespace factor
   4 {
   5
   6 callback_heap::callback_heap(cell size, factor_vm *parent_) :
   7         seg(new segment(size,true)),
   8         here(seg->start),
   9         parent(parent_) {}
  10
  11 callback_heap::~callback_heap()
  12 {
  13         delete seg;
  14         seg = NULL;
  15 }
  16
  17 void factor_vm::init_callbacks(cell size)
  18 {
  19         callbacks = new callback_heap(size,this);
  20 }
  21
  22 void callback_heap::store_callback_operand(code_block *stub, cell index, cell value)
  23 {
  24         tagged<array> code_template(parent->special_objects[CALLBACK_STUB]);
  25
  26         cell rel_class = untag_fixnum(array_nth(code_template.untagged(),3 * index + 1));
  27         cell rel_type  = untag_fixnum(array_nth(code_template.untagged(),3 * index + 2));
  28         cell offset    = untag_fixnum(array_nth(code_template.untagged(),3 * index + 3));
  29
  30         relocation_entry rel(
  31                 (relocation_type)rel_type,
  32                 (relocation_class)rel_class,
  33                 offset);
  34
  35         instruction_operand op(rel,stub,0);
  36         op.store_value(value);
  37 }
  38
  39 void callback_heap::update(code_block *stub)
  40 {
  41         store_callback_operand(stub,1,(cell)callback_entry_point(stub));
  42         stub->flush_icache();
  43 }
  44
  45 code_block *callback_heap::add(cell owner, cell return_rewind)
  46 {
  47         tagged<array> code_template(parent->special_objects[CALLBACK_STUB]);
  48         tagged<byte_array> insns(array_nth(code_template.untagged(),0));
  49         cell size = array_capacity(insns.untagged());
  50
  51         cell bump = align(size + sizeof(code_block),data_alignment);
  52         if(here + bump > seg->end) fatal_error("Out of callback space",0);
  53
  54         free_heap_block *free_block = (free_heap_block *)here;
  55         free_block->make_free(bump);
  56         here += bump;
  57
  58         code_block *stub = (code_block *)free_block;
  59         stub->owner = owner;
  60         stub->parameters = false_object;
  61         stub->relocation = false_object;
  62
  63         memcpy(stub->entry_point(),insns->data<void>(),size);
  64
  65         /* Store VM pointer */
  66         store_callback_operand(stub,0,(cell)parent);
  67         store_callback_operand(stub,2,(cell)parent);
  68
  69         /* On x86, the RET instruction takes an argument which depends on
  70         the callback's calling convention */
  71 #if defined(FACTOR_X86) || defined(FACTOR_AMD64)
  72         store_callback_operand(stub,3,return_rewind);
  73 #endif
  74
  75         update(stub);
  76
  77         return stub;
  78 }
  79
  80 struct callback_updater {
  81         callback_heap *callbacks;
  82
  83         explicit callback_updater(callback_heap *callbacks_) : callbacks(callbacks_) {}
  84
  85         void operator()(code_block *stub)
  86         {
  87                 callbacks->update(stub);
  88         }
  89 };
  90
  91 void callback_heap::update()
  92 {
  93         callback_updater updater(this);
  94         each_callback(updater);
  95 }
  96
  97 void factor_vm::primitive_callback()
  98 {
  99         cell return_rewind = to_cell(ctx->pop());
 100         tagged<word> w(ctx->pop());
 101
 102         w.untag_check(this);
 103         ctx->push(allot_alien(callbacks->add(w.value(),return_rewind)->entry_point()));
 104 }
 105
 106 }