private int IndexOfCharOrdinalIgnoreCase(char value) { if (!char.IsAscii(value)) { return(CompareInfo.Invariant.IndexOf(this, value, CompareOptions.OrdinalIgnoreCase)); } if (char.IsAsciiLetter(value)) { char valueUc = (char)(value | 0x20); char valueLc = (char)(value & ~0x20); return(SpanHelpers.IndexOfAnyChar(ref _firstChar, valueLc, valueUc, Length)); } return(SpanHelpers.IndexOfChar(ref _firstChar, value, Length)); }