Function FastUInt64ToBufferLeft

be/src/gutil/strings/numbers.cc:1023–1063

}

char* FastUInt64ToBufferLeft(uint64 u64, char* buffer) {
  uint digits;
  const char *ASCII_digits = nullptr;

  uint32 u = static_cast<uint32>(u64);
  if (u == u64) return FastUInt32ToBufferLeft(u, buffer);

  uint64 top_11_digits = u64 / 1000000000;
  buffer = FastUInt64ToBufferLeft(top_11_digits, buffer);
  u = u64 - (top_11_digits * 1000000000);

  digits = u / 10000000;  // 10,000,000
  DCHECK_LT(digits, 100);
  ASCII_digits = two_ASCII_digits[digits];
  buffer[0] = ASCII_digits[0];
  buffer[1] = ASCII_digits[1];
  buffer += 2;
  u -= digits * 10000000;  // 10,000,000
  digits = u / 100000;  // 100,000
  ASCII_digits = two_ASCII_digits[digits];
  buffer[0] = ASCII_digits[0];
  buffer[1] = ASCII_digits[1];
  buffer += 2;
  u -= digits * 100000;  // 100,000
  digits = u / 1000;  // 1,000
  ASCII_digits = two_ASCII_digits[digits];
  buffer[0] = ASCII_digits[0];
  buffer[1] = ASCII_digits[1];
  buffer += 2;
  u -= digits * 1000;  // 1,000
  digits = u / 10;
  ASCII_digits = two_ASCII_digits[digits];
  buffer[0] = ASCII_digits[0];
  buffer[1] = ASCII_digits[1];
  buffer += 2;
  u -= digits * 10;
  digits = u;
  *buffer++ = '0' + digits;
  *buffer = 0;
  return buffer;
}

char* FastInt64ToBufferLeft(int64 i, char* buffer) {
  uint64 u = i;