path: root/cpp/042new.cc

//: A simple memory allocator to create space for new variables at runtime.

:(scenarios run)
:(scenario new)
# call new two times with identical arguments; you should get back different results
recipe main [
  1:address:integer/raw <- new integer:type
  2:address:integer/raw <- new integer:type
  3:boolean/raw <- equal 1:address:integer/raw, 2:address:integer/raw
]
+mem: storing 0 in location 3

:(before "End Globals")
size_t Reserved_for_tests = 1000;
index_t Memory_allocated_until = Reserved_for_tests;
size_t Initial_memory_per_routine = 100000;
:(before "End Setup")
Memory_allocated_until = Reserved_for_tests;
Initial_memory_per_routine = 100000;
:(before "End routine Fields")
index_t alloc, alloc_max;
:(before "End routine Constructor")
alloc = Memory_allocated_until;
Memory_allocated_until += Initial_memory_per_routine;
alloc_max = Memory_allocated_until;
trace("new") << "routine allocated memory from " << alloc << " to " << alloc_max;

//:: First handle 'type' operands.

:(before "End Mu Types Initialization")
Type_number["type"] = 0;
:(after "Per-recipe Transforms")
// replace type names with type_numbers
if (inst.operation == Recipe_number["new"]) {
  // first arg must be of type 'type'
  assert(inst.ingredients.size() >= 1);
//?   cout << inst.ingredients[0].to_string() << '\n'; //? 1
  assert(isa_literal(inst.ingredients[0]));
  if (inst.ingredients[0].properties[0].second[0] == "type") {
    inst.ingredients[0].set_value(Type_number[inst.ingredients[0].name]);
  }
  trace("new") << inst.ingredients[0].name << " -> " << inst.ingredients[0].value;
}

//:: Now implement the primitive recipe.

:(before "End Primitive Recipe Declarations")
NEW,
:(before "End Primitive Recipe Numbers")
Recipe_number["new"] = NEW;
:(before "End Primitive Recipe Implementations")
case NEW: {
  // compute the space we need
  size_t size = 0;
  size_t array_length = 0;
  {
    vector<type_number> type;
    type.push_back(current_instruction().ingredients[0].value);
    if (current_instruction().ingredients.size() > 1) {
      // array
      vector<long long int> capacity = read_memory(current_instruction().ingredients[1]);
      array_length = capacity[0];
      trace("mem") << "array size is " << array_length;
      size = array_length*size_of(type) + /*space for length*/1;
    }
    else {
      // scalar
      size = size_of(type);
    }
  }
  // compute the resulting location
  // really crappy at the moment
  assert(size <= Initial_memory_per_routine);
  if (Current_routine->alloc + size >= Current_routine->alloc_max) {
    // waste the remaining space and create a new chunk
    Current_routine->alloc = Memory_allocated_until;
    Memory_allocated_until += Initial_memory_per_routine;
    Current_routine->alloc_max = Memory_allocated_until;
    trace("new") << "routine allocated memory from " << Current_routine->alloc << " to " << Current_routine->alloc_max;
  }
  const index_t result = Current_routine->alloc;
  trace("mem") << "new alloc: " << result;
  if (current_instruction().ingredients.size() > 1) {
    // initialize array
    Memory[result] = array_length;
  }
  // write result to memory
  vector<long long int> tmp;
  tmp.push_back(Current_routine->alloc);
  write_memory(current_instruction().products[0], tmp);
  // bump
  Current_routine->alloc += size;
  // no support for reclaiming memory
  assert(Current_routine->alloc <= Current_routine->alloc_max);
  break;
}

:(scenario new_array)
recipe main [
  1:address:array:integer/raw <- new integer:type, 5:literal
  2:address:integer/raw <- new integer:type
  3:integer/raw <- subtract 2:address:integer/raw, 1:address:array:integer/raw
]
+run: instruction main/0
+mem: array size is 5
+run: instruction main/1
+run: instruction main/2
+mem: storing 6 in location 3

//: Make sure that each routine gets a different alloc to start.
:(scenario new_concurrent)
recipe f1 [
  start-running f2:recipe
  1:address:integer/raw <- new integer:type
]
recipe f2 [
  2:address:integer/raw <- new integer:type
  # hack: assumes scheduler implementation
  3:boolean/raw <- equal 1:address:integer/raw, 2:address:integer/raw
]
+mem: storing 0 in location 3

//: If a routine runs out of its initial allocation, it should allocate more.
:(scenario new_overflow)
% Initial_memory_per_routine = 2;
recipe main [
  1:address:integer/raw <- new integer:type
  2:address:point/raw <- new point:type  # not enough room in initial page
]
+new: routine allocated memory from 1000 to 1002
+new: routine allocated memory from 1002 to 1004

//:: Next, extend 'new' to handle a string literal argument.

:(scenario new_string)
recipe main [
  1:address:array:character <- new [abc def]
  2:character <- index 1:address:array:character/deref, 5:literal
]
# integer code for 'e'
+mem: storing 101 in location 2

:(after "case NEW" following "Primitive Recipe Implementations")
if (current_instruction().ingredients[0].properties[0].second[0] == "literal-string") {
  // allocate an array just large enough for it
  vector<long long int> result;
  result.push_back(Current_routine->alloc);
  write_memory(current_instruction().products[0], result);
  // assume that all characters fit in a single location
//?   cout << "new string literal: " << current_instruction().ingredients[0].name << '\n'; //? 1
  Memory[Current_routine->alloc++] = current_instruction().ingredients[0].name.size();
  for (index_t i = 0; i < current_instruction().ingredients[0].name.size(); ++i) {
    Memory[Current_routine->alloc++] = current_instruction().ingredients[0].name[i];
  }
  // mu strings are not null-terminated in memory
  break;
}