<!DOCTYPE html> <head> <!-- Copyright (C) 2007 Apple Inc. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. --> <title>SunSpider bitops-3bit-bits-in-byte</title> </head> <body> <h3>bitops-3bit-bits-in-byte</h3> <div id="console"> </div> <script> var _sunSpiderStartDate = new Date(); // 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<500; x++) for(var y=0; y<256; y++) func(y); } TimeFunc(fast3bitlookup); var _sunSpiderInterval = new Date() - _sunSpiderStartDate; document.getElementById("console").innerHTML = _sunSpiderInterval; </script> </body> </html>