// file included directly

bool validate_ascii(const char *buf, size_t len) {
  const char *end = buf + len;
  const __m512i ascii = _mm512_set1_epi8((uint8_t)0x80);
  __m512i running_or = _mm512_setzero_si512();
  for (; end - buf >= 64; buf += 64) {
    const __m512i utf8 = _mm512_loadu_si512((const __m512i *)buf);
    running_or = _mm512_ternarylogic_epi32(running_or, utf8, ascii,
                                           0xf8); // running_or | (utf8 & ascii)
  }
  if (buf < end) {
    const __m512i utf8 = _mm512_maskz_loadu_epi8(
        (uint64_t(1) << (end - buf)) - 1, (const __m512i *)buf);
    running_or = _mm512_ternarylogic_epi32(running_or, utf8, ascii,
                                           0xf8); // running_or | (utf8 & ascii)
  }
  return (_mm512_test_epi8_mask(running_or, running_or) == 0);
}