1// Copyright (c) 2004 by Arthur Langereis (arthur_ext at domain xfinitegames, tld com 2 3var result = 0; 4 5// 1 op = 6 ANDs, 3 SHRs, 3 SHLs, 4 assigns, 2 ADDs 6// O(1) 7function fast3bitlookup(b) { 8var c, bi3b = 0xE994; // 0b1110 1001 1001 0100; // 3 2 2 1 2 1 1 0 9c = 3 & (bi3b >> ((b << 1) & 14)); 10c += 3 & (bi3b >> ((b >> 2) & 14)); 11c += 3 & (bi3b >> ((b >> 5) & 6)); 12return c; 13 14/* 15lir4,0xE994; 9 instructions, no memory access, minimal register dependence, 6 shifts, 2 adds, 1 inline assign 16rlwinmr5,r3,1,28,30 17rlwinmr6,r3,30,28,30 18rlwinmr7,r3,27,29,30 19rlwnmr8,r4,r5,30,31 20rlwnmr9,r4,r6,30,31 21rlwnmr10,r4,r7,30,31 22addr3,r8,r9 23addr3,r3,r10 24*/ 25} 26 27 28function TimeFunc(func) { 29var x, y, t; 30var sum = 0; 31for(var x=0; x<500; x++) 32for(var y=0; y<256; y++) sum += func(y); 33return sum; 34} 35 36sum = TimeFunc(fast3bitlookup); 37