factor/vm/strings.cpp

#include "master.hpp"

namespace factor {

/* Allocates memory */
string* factor_vm::allot_string_internal(cell capacity) {
  string* str = allot<string>(string_size(capacity));

  str->length = tag_fixnum(capacity);
  str->hashcode = false_object;
  str->aux = false_object;

  return str;
}

/* Allocates memory */
void factor_vm::fill_string(string* str_, cell start, cell capacity,
                            cell fill) {
  data_root<string> str(str_, this);

  if (fill <= 0x7f)
    memset(&str->data()[start], (uint8_t)fill, capacity - start);
  else {
    byte_array* aux;
    if (to_boolean(str->aux))
      aux = untag<byte_array>(str->aux);
    else {
      aux =
          allot_uninitialized_array<byte_array>(untag_fixnum(str->length) * 2);
      str->aux = tag<byte_array>(aux);
      write_barrier(&str->aux);
    }

    uint8_t lo_fill = (uint8_t)((fill & 0x7f) | 0x80);
    uint16_t hi_fill = (uint16_t)((fill >> 7) ^ 0x1);
    memset(&str->data()[start], lo_fill, capacity - start);
    memset_2(&aux->data<uint16_t>()[start], hi_fill,
             (capacity - start) * sizeof(uint16_t));
  }
}

/* Allocates memory */
string* factor_vm::allot_string(cell capacity, cell fill) {
  data_root<string> str(allot_string_internal(capacity), this);
  fill_string(str.untagged(), 0, capacity, fill);
  return str.untagged();
}

/* Allocates memory */
void factor_vm::primitive_string() {
  cell initial = to_cell(ctx->pop());
  cell length = unbox_array_size();
  ctx->push(tag<string>(allot_string(length, initial)));
}

bool factor_vm::reallot_string_in_place_p(string* str, cell capacity) {
  return data->nursery->contains_p(str) &&
         (!to_boolean(str->aux) ||
          data->nursery->contains_p(untag<byte_array>(str->aux))) &&
         capacity <= string_capacity(str);
}

/* Allocates memory */
string* factor_vm::reallot_string(string* str_, cell capacity) {
  data_root<string> str(str_, this);

  if (reallot_string_in_place_p(str.untagged(), capacity)) {
    str->length = tag_fixnum(capacity);

    if (to_boolean(str->aux)) {
      byte_array* aux = untag<byte_array>(str->aux);
      aux->capacity = tag_fixnum(capacity * 2);
    }

    return str.untagged();
  } else {
    cell to_copy = string_capacity(str.untagged());
    if (capacity < to_copy)
      to_copy = capacity;

    data_root<string> new_str(allot_string_internal(capacity), this);

    memcpy(new_str->data(), str->data(), to_copy);

    if (to_boolean(str->aux)) {
      byte_array* new_aux = allot_uninitialized_array<byte_array>(capacity * 2);
      new_str->aux = tag<byte_array>(new_aux);
      write_barrier(&new_str->aux);

      byte_array* aux = untag<byte_array>(str->aux);
      memcpy(new_aux->data<uint16_t>(), aux->data<uint16_t>(),
             to_copy * sizeof(uint16_t));
    }

    fill_string(new_str.untagged(), to_copy, capacity, '\0');
    return new_str.untagged();
  }
}

/* Allocates memory */
void factor_vm::primitive_resize_string() {
  data_root<string> str(ctx->pop(), this);
  check_tagged(str);
  cell capacity = unbox_array_size();
  ctx->push(tag<string>(reallot_string(str.untagged(), capacity)));
}

void factor_vm::primitive_set_string_nth_fast() {
  string* str = untag<string>(ctx->pop());
  cell index = untag_fixnum(ctx->pop());
  cell value = untag_fixnum(ctx->pop());
  str->data()[index] = (uint8_t)value;
}

}