Author: Walter Faxon
Date: 11:55:31 12/22/02
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Hi, Matt.
In your latest bitscan.c, the routine BitSearchReset_IntMatt(), there is a
sequence:
...
mov ecx, eax
shl ecx, 16
add eax, ecx
sub al, ah
mov ecx, DWORD PTR [bb] <=== whaz dis doin' heah?
and eax, 0xFF
mov al, [LSB_64_table+eax-51]
jmp ScanAgain
...
That's all the references to ecx, so the load looks like an artifact. Haven't
checked the other code, but my compiler also sometimes does silly things like
this. (One might expect it to affect the timings... :)
Another suggestion: once you've got the bit number, do something with it. A
little more realistic.
By the way, thanks again for looking into this problem in so much detail. If we
can't scan bits efficiently, it won't be due to your lack of effort!
-- Walter
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