Function insert_utf8_char

base/string.cpp:26–63

Based on Allegro Unicode code (allegro/src/unicode.c)

// Based on Allegro Unicode code (allegro/src/unicode.c)
static std::size_t insert_utf8_char(const codepoint_t chr, std::string* result = nullptr)
{
  int size, bits, b, i;

  if (chr < 128) {
    if (result)
      result->push_back(chr);
    return 1;
  }

  bits = 7;
  while (chr >= (1 << bits))
    bits++;

  size = 2;
  b = 11;

  while (b < bits) {
    size++;
    b += 5;
  }

  if (result) {
    b -= (7 - size);
    int firstbyte = chr >> b;
    for (i = 0; i < size; i++)
      firstbyte |= (0x80 >> i);

    result->push_back(firstbyte);

    for (i = 1; i < size; i++) {
      b -= 6;
      result->push_back(0x80 | ((chr >> b) & 0x3F));
    }
  }

  return size;
}

std::string string_printf(const char* format, ...)
{