testing/performance/talos/page_load_test/sunspider/bitops-3bit-bits-in-byte.html

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  27
  28 <title>SunSpider bitops-3bit-bits-in-byte</title>
  29 <link rel="stylesheet" href="sunspider.css"></link>
  30 </head>
  31
  32 <body>
  33 <h3>bitops-3bit-bits-in-byte</h3>
  34 <div id="console">
  35 </div>
  36 <script>
  37
  38
  39 // Copyright (c) 2004 by Arthur Langereis (arthur_ext at domain xfinitegames, tld com
  40
  41 // 1 op = 6 ANDs, 3 SHRs, 3 SHLs, 4 assigns, 2 ADDs
  42 // O(1)
  43 function fast3bitlookup(b) {
  44 var c, bi3b = 0xE994; // 0b1110 1001 1001 0100; // 3 2 2 1  2 1 1 0
  45 c  = 3 & (bi3b >> ((b << 1) & 14));
  46 c += 3 & (bi3b >> ((b >> 2) & 14));
  47 c += 3 & (bi3b >> ((b >> 5) & 6));
  48 return c;
  49
  50 /*
  51 lir4,0xE994; 9 instructions, no memory access, minimal register dependence, 6 shifts, 2 adds, 1 inline assign
  52 rlwinmr5,r3,1,28,30
  53 rlwinmr6,r3,30,28,30
  54 rlwinmr7,r3,27,29,30
  55 rlwnmr8,r4,r5,30,31
  56 rlwnmr9,r4,r6,30,31
  57 rlwnmr10,r4,r7,30,31
  58 addr3,r8,r9
  59 addr3,r3,r10
  60 */
  61 }
  62
  63
  64 function TimeFunc(func) {
  65 var x, y, t;
  66 for(var x=0; x<500; x++)
  67 for(var y=0; y<256; y++) func(y);
  68 }
  69
  70 TimeFunc(fast3bitlookup);
  71
  72
  73
  74 </script>
  75
  76
  77 </body>
  78 </html>