sunspider-bitops-3bit-bits-in-byte.html

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// Copyright (c) 2004 by Arthur Langereis (arthur_ext at domain xfinitegames, tld com

// 1 op = 6 ANDs, 3 SHRs, 3 SHLs, 4 assigns, 2 ADDs

// O(1)

function fast3bitlookup(b) {

var c, bi3b = 0xE994; // 0b1110 1001 1001 0100; // 3 2 2 1  2 1 1 0

c  = 3 & (bi3b >> ((b << 1) & 14));

c += 3 & (bi3b >> ((b >> 2) & 14));

c += 3 & (bi3b >> ((b >> 5) & 6));

return c;

/*

lir4,0xE994; 9 instructions, no memory access, minimal register dependence, 6 shifts, 2 adds, 1 inline assign

rlwinmr5,r3,1,28,30

rlwinmr6,r3,30,28,30

rlwinmr7,r3,27,29,30

rlwnmr8,r4,r5,30,31

rlwnmr9,r4,r6,30,31

rlwnmr10,r4,r7,30,31

addr3,r8,r9

addr3,r3,r10

*/

function TimeFunc(func) {

var x, y, t;

for(var x=0; x<250; x++)

for(var y=0; y<256; y++) func(y);

window.onload = function(){ startTest("sunspider-bitops-3bit-bits-in-byte", '3664f684');

test("3bit bits in byte", function(){

	TimeFunc(fast3bitlookup);

});

endTest(); };

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