path: root/032array.cc

//: Arrays contain a variable number of elements of the same type. Their value
//: starts with the length of the array.
//:
//: You can create arrays of containers, but containers can only contain
//: elements of a fixed size, so you can't create containers containing arrays.
//: Create containers containing addresses to arrays instead.

//: Tests in this layer often explicitly setup memory before reading it as an
//: array. Don't do this in general. I'm tagging exceptions with /raw to
//: avoid warnings.
:(scenario copy_array)
# Arrays can be copied around with a single instruction just like numbers,
# no matter how large they are.
recipe main [
  1:number <- copy 3:literal  # length
  2:number <- copy 14:literal
  3:number <- copy 15:literal
  4:number <- copy 16:literal
  5:array:number <- copy 1:array:number/raw  # unsafe
]
+mem: storing 3 in location 5
+mem: storing 14 in location 6
+mem: storing 15 in location 7
+mem: storing 16 in location 8

:(scenario copy_array_indirect)
recipe main [
  1:number <- copy 3:literal  # length
  2:number <- copy 14:literal
  3:number <- copy 15:literal
  4:number <- copy 16:literal
  5:address:array:number <- copy 1:literal
  6:array:number <- copy 5:address:array:number/deref
]
+mem: storing 3 in location 6
+mem: storing 14 in location 7
+mem: storing 15 in location 8
+mem: storing 16 in location 9

//: disable the size mismatch check since the destination array need not be initialized
:(after "bool size_mismatch(const reagent& x, const vector<double>& data)")
if (x.types.at(0) == Type_number["array"]) return false;
:(after "long long int size_of(const reagent& r)")
  if (r.types.at(0) == Type_number["array"]) {
    assert(SIZE(r.types) > 1);
    // skip the 'array' type to get at the element type
    return 1 + Memory[r.value]*size_of(array_element(r.types));
  }

//:: To access elements of an array, use 'index'

:(scenario index)
recipe main [
  1:number <- copy 3:literal  # length
  2:number <- copy 14:literal
  3:number <- copy 15:literal
  4:number <- copy 16:literal
  5:number <- index 1:array:number/raw, 0:literal  # unsafe
]
+mem: storing 14 in location 5

:(scenario index_direct_offset)
recipe main [
  1:number <- copy 3:literal  # length
  2:number <- copy 14:literal
  3:number <- copy 15:literal
  4:number <- copy 16:literal
  5:number <- copy 0:literal
  6:number <- index 1:array:number/raw, 5:number  # unsafe
]
+mem: storing 14 in location 6

:(before "End Primitive Recipe Declarations")
INDEX,
:(before "End Primitive Recipe Numbers")
Recipe_number["index"] = INDEX;
:(before "End Primitive Recipe Implementations")
case INDEX: {
//?   if (Trace_stream) Trace_stream->dump_layer = "run"; //? 1
  reagent base = canonize(current_instruction().ingredients.at(0));
//?   trace(Primitive_recipe_depth, "run") << "ingredient 0 after canonize: " << base.to_string(); //? 1
  long long int base_address = base.value;
  assert(base.types.at(0) == Type_number["array"]);
  reagent offset = canonize(current_instruction().ingredients.at(1));
//?   trace(Primitive_recipe_depth, "run") << "ingredient 1 after canonize: " << offset.to_string(); //? 1
  vector<double> offset_val(read_memory(offset));
  vector<type_number> element_type = array_element(base.types);
//?   trace(Primitive_recipe_depth, "run") << "offset: " << offset_val.at(0); //? 1
//?   trace(Primitive_recipe_depth, "run") << "size of elements: " << size_of(element_type); //? 1
  long long int src = base_address + 1 + offset_val.at(0)*size_of(element_type);
  trace(Primitive_recipe_depth, "run") << "address to copy is " << src;
  trace(Primitive_recipe_depth, "run") << "its type is " << Type[element_type.at(0)].name;
  reagent tmp;
  tmp.set_value(src);
  copy(element_type.begin(), element_type.end(), inserter(tmp.types, tmp.types.begin()));
  products.push_back(read_memory(tmp));
  break;
}

:(code)
vector<type_number> array_element(const vector<type_number>& types) {
  return vector<type_number>(++types.begin(), types.end());
}

:(scenario index_address)
recipe main [
  1:number <- copy 3:literal  # length
  2:number <- copy 14:literal
  3:number <- copy 15:literal
  4:number <- copy 16:literal
  5:number <- index-address 1:array:number/raw, 0:literal  # unsafe
]
+mem: storing 2 in location 5

//:: To write to elements of containers, you need their address.

:(scenario index_indirect)
recipe main [
  1:number <- copy 3:literal  # length
  2:number <- copy 14:literal
  3:number <- copy 15:literal
  4:number <- copy 16:literal
  5:address:array:number <- copy 1:literal
  6:number <- index 5:address:array:number/deref, 1:literal
]
+mem: storing 15 in location 6

:(before "End Primitive Recipe Declarations")
INDEX_ADDRESS,
:(before "End Primitive Recipe Numbers")
Recipe_number["index-address"] = INDEX_ADDRESS;
:(before "End Primitive Recipe Implementations")
case INDEX_ADDRESS: {
  reagent base = canonize(current_instruction().ingredients.at(0));
  long long int base_address = base.value;
  assert(base.types.at(0) == Type_number["array"]);
  reagent offset = canonize(current_instruction().ingredients.at(1));
  vector<double> offset_val(read_memory(offset));
  vector<type_number> element_type = array_element(base.types);
  long long int result = base_address + 1 + offset_val.at(0)*size_of(element_type);
  products.resize(1);
  products.at(0).push_back(result);
  break;
}

//:: compute the length of an array

:(scenario array_length)
recipe main [
  1:number <- copy 3:literal  # length
  2:number <- copy 14:literal
  3:number <- copy 15:literal
  4:number <- copy 16:literal
  5:number <- length 1:array:number/raw  # unsafe
]
+mem: storing 3 in location 5

:(before "End Primitive Recipe Declarations")
LENGTH,
:(before "End Primitive Recipe Numbers")
Recipe_number["length"] = LENGTH;
:(before "End Primitive Recipe Implementations")
case LENGTH: {
  reagent x = canonize(current_instruction().ingredients.at(0));
  if (x.types.at(0) != Type_number["array"]) {
    raise << "tried to calculate length of non-array " << x.to_string() << '\n';
    break;
  }
  products.resize(1);
  products.at(0).push_back(Memory[x.value]);
  break;
}