/js/src/metrics/jint/sunspider/bitops-3bit-bits-in-byte.js

http://github.com/zpao/v8monkey · JavaScript · 37 lines · 14 code · 5 blank · 18 comment · 2 complexity · 68289bcc2de42778b9baee081d3e02f9 MD5 · raw file

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