void nghttp2_downcase(uint8_t *s, size_t len) {
  size_t i;
  for (i = 0; i < len; ++i) {
    s[i] = DOWNCASE_TBL[s[i]];
  }
}
void nghttp2_downcase(uint8_t *s, size_t len) {
  size_t i;
  for (i = 0; i < len; ++i) {
    s[i] = DOWNCASE_TBL[s[i]];
  }
}