1 // Copyright (c) 2004 by Arthur Langereis (arthur_ext at domain xfinitegames, tld com
3 // 1 op = 6 ANDs, 3 SHRs, 3 SHLs, 4 assigns, 2 ADDs
5 function fast3bitlookup(b) {
6 var c, bi3b = 0xE994; // 0b1110 1001 1001 0100; // 3 2 2 1 2 1 1 0
7 c = 3 & (bi3b >> ((b << 1) & 14));
8 c += 3 & (bi3b >> ((b >> 2) & 14));
9 c += 3 & (bi3b >> ((b >> 5) & 6));
13 lir4,0xE994; 9 instructions, no memory access, minimal register dependence, 6 shifts, 2 adds, 1 inline assign
26 function TimeFunc(func) {
28 for(var x=0; x<500; x++)
29 for(var y=0; y<256; y++) func(y);
32 TimeFunc(fast3bitlookup);