/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
- // 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;
- /* BEGIN LOOP */
- for(var x=0; x<500; x++) {
- /* BEGIN LOOP */
- for(var y=0; y<256; y++) func(y);
- /* END LOOP */
- }
- /* END LOOP */
- }
- TimeFunc(fast3bitlookup);