Table lookups - this is pretty definitive

[Alix Pexton via Digitalmars-d]

I tested this against the others...
(with "-inline -release -O" of course)

===

uint[8] tab4; // bitop function only work on uints
static this()
{
     for (size_t u = 0; u < 0x100; ++u)
     {
         if (isIdentifierChar0(cast(ubyte)u))
         {
             bts(tab4.ptr, u);
         }
     }
}

bool isIdentifierChar4(ubyte c)
{
	return bt(tab4.ptr, c) != 0;
}

===

it takes about 3 times as long (about the same as the original 
isIdentifierChar1, that used lots of &&s and ||s).

So 2 shifts, 2 ands and a compare to zero, beats core.bitop.

for clarity, the output of my benchmark for all 5 version was

Milliseconds 21 15 2 5 15

the 2 (which on some runs was a 3) is Walter's table of bools, the 5 is 
my table of ulongs and the 15 on the end is core.bitop.

Short of delving into the asm, which I'm trying to avoid, any other 
suggestions for speed-ups?

A...