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Re: Bit Interleaving, Instruction Set Support for

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On 9/6/11 5:12 AM, Piotr Wyderski wrote:
> Andy "Krazy" Glew wrote:
>
> Thanks for starting the thread, as bit operations are of vital importance in my low-level
> algorithms. Apart the operations
> mentioned previously, I would like to have the following instruction:
>
> bit_chunk_check(x, n):
>
> where x is an unsigned integer and n is a positive integer.
> The instruction checks whether x contains a chunk of n consecutive
> set bits and returns an index of the first/last/some such a chunk.
> It is a generalization of bsf/bsr.

Kind of a run-length-encoding. Would be neat if you could deal
with a bunch of bits. The result would be a count of alternating
zeroes and ones. So for example:

value	result (four 8-bit values in decimal)
0	32,0,0,0	; 32 zeroes, 0 ones
-1	0,32,0,0	; 0 zeroes, 32 ones
257	23,1,7,1	;
13	27,1,1,1	; actual encoding: 27,1,1,1,1,1 but only the first 4 can be returned

Also need a clz (clear leading zeroes) to pick up for example the
last two runs of 13 in the next round. Very useful in array
programming. A == B will yield a bitmap where A[i] == B[i]. To
then pick up those values from A or B (or another related array)
you need indices of places where A & B match.

Probably not doable in one cycle. But even knocking off one run
of zeroes and one of ones can be handy.

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Thread

Bit Interleaving, Instruction Set Support for "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-09-05 16:23 -0700
  Re: Bit Interleaving, Instruction Set Support for Mark Thorson <nospam@sonic.net> - 2011-09-05 20:07 -0800
    Re: Bit Interleaving, Instruction Set Support for "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-09-05 21:25 -0700
      Re: Bit Interleaving, Instruction Set Support for Andrew Reilly <areilly---@bigpond.net.au> - 2011-09-06 05:09 +0000
        Re: Bit Interleaving, Instruction Set Support for torbenm@diku.dk (Torben Ægidius Mogensen) - 2011-09-06 10:20 +0200
          Re: Bit Interleaving, Instruction Set Support for Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-09-06 13:28 +0200
            Re: Bit Interleaving, Instruction Set Support for "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-09-06 11:29 -0700
          Re: Bit Interleaving, Instruction Set Support for "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-09-06 11:21 -0700
          Re: Bit Interleaving, Instruction Set Support for timcaffrey@aol.com (Tim McCaffrey) - 2011-09-09 19:10 +0000
            Re: Bit Interleaving, Instruction Set Support for "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-09-10 12:50 -0700
            Re: Bit Interleaving, Instruction Set Support for torbenm@diku.dk (Torben Ægidius Mogensen) - 2011-09-13 10:34 +0200
      Re: Bit Interleaving, Instruction Set Support for Mark Thorson <nospam@sonic.net> - 2011-09-07 12:43 -0800
        Re: Bit Interleaving, Instruction Set Support for "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-09-10 12:27 -0700
          Re: Bit Interleaving, Instruction Set Support for "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-09-11 21:05 -0700
        Re: Bit Interleaving, Instruction Set Support for EricP <ThatWouldBeTelling@thevillage.com> - 2011-09-10 16:57 -0400
          Re: Bit Interleaving, Instruction Set Support for George Neuner <gneuner2@comcast.net> - 2011-09-10 23:14 -0400
            Re: Bit Interleaving, Instruction Set Support for nmm1@cam.ac.uk - 2011-09-11 10:16 +0100
              Re: Bit Interleaving, Instruction Set Support for EricP <ThatWouldBeTelling@thevillage.com> - 2011-09-11 12:30 -0400
    Re: Bit Interleaving, Instruction Set Support for Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-09-06 13:25 +0200
  Re: Bit Interleaving, Instruction Set Support for Quadibloc <jsavard@ecn.ab.ca> - 2011-09-05 21:02 -0700
  Re: Bit Interleaving, Instruction Set Support for Piotr Wyderski <peter.pan@neverland.mil> - 2011-09-06 14:12 +0200
    Re: Bit Interleaving, Instruction Set Support for Bakul Shah <usenet@bitblocks.com> - 2011-09-06 11:49 -0700
      Re: Bit Interleaving, Instruction Set Support for Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-09-07 11:18 +0200
        Re: Bit Interleaving, Instruction Set Support for Thomas Womack <twomack@chiark.greenend.org.uk> - 2011-09-07 10:54 +0100
          Re: Bit Interleaving, Instruction Set Support for Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-09-07 20:27 +0200
  Re: Bit Interleaving, Instruction Set Support for MitchAlsup <MitchAlsup@aol.com> - 2011-09-07 12:23 -0700

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