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Subject: Re: FirstBit() in assembler

Author: Dan Newman

Date: 12:19:31 01/14/02

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On January 13, 2002 at 16:32:01, David Rasmussen wrote:

>On January 13, 2002 at 13:20:52, Dan Newman wrote:
>
>>On January 13, 2002 at 08:48:13, David Rasmussen wrote:
>>
>>
>>I do something like this (Dann Corbit's trick):
>>
>>        bsf eax dword ptr bitboard+4
>>        add eax 32
>>        bsf eax dword ptr bitboard
>>
>
>I get it now... Is there a similar trick for a "LastBit()" function?
>
>/David

I think something like this should work:

        bsr eax dword ptr bitboard
        sub eax 32
        bsr eax dword ptr bitboard+4
        add eax 32

which makes using last-bit a bit more expensive, but it's still
straight line code...

-Dan.

• Re: FirstBit() in assembler - the fastest LastBit() Severi Salminen 05:49:16 01/15/02
  • Re: FirstBit() in assembler - the fastest LastBit() David Rasmussen 06:00:37 01/15/02
    • Re: FirstBit() in assembler - the fastest LastBit() Severi Salminen 11:52:07 01/15/02
• Re: FirstBit() in assembler David Rasmussen 14:43:41 01/14/02
  • Re: FirstBit() in assembler Severi Salminen 01:36:17 01/15/02
    • Re: FirstBit() in assembler Dan Newman 09:53:02 01/15/02
      • Re: FirstBit() in assembler Bo Persson 10:58:56 01/15/02

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