Author: Dave Gomboc
Date: 00:04:30 09/20/99
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On September 17, 1999 at 10:14:19, Dave Gomboc wrote: >On September 17, 1999 at 10:00:47, Brian Richardson wrote: > >>On September 16, 1999 at 17:07:08, J. Wesley Cleveland wrote: >> >>>On September 15, 1999 at 16:57:30, Brian Richardson wrote: >>> >>>>I have looked at Intel's IA64 architecture guide and can't find these >>>>instructions, although there is a popcnt. Am I missing something? >>> >>>There is a Compute Zero Index, which would allow you to do it in 3 instructions. >> >>I saw the czx instructions, but they find the first zero byte (or 2 bytes). >>How would you use czx to find the first non-zero element? >>Also, seems like table lookup would still be needed to find the first/last bit >>set? > >xor all of the bits first > >Dave Sorry, I misunderstood the operation that czx performs. I thought it was acting as a "find first zero (bit! :-)" Dave
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