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Groups > comp.lang.c > #19917

Re: ffs16

From jgk@panix.com (Joe keane)
Newsgroups comp.arch, comp.lang.c
Subject Re: ffs16
Date 2012-04-25 20:08 +0000
Organization Public Access Networks Corp.
Message-ID <jn9lk0$hp4$1@reader1.panix.com> (permalink)
References <jn1tku$pga$1@reader1.panix.com> <v65g69-41e2.ln1@ntp6.tmsw.no> <jn6tjv$a39$1@reader1.panix.com> <9kmj69-hhi2.ln1@ntp6.tmsw.no>

Cross-posted to 2 groups.

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In article <9kmj69-hhi2.ln1@ntp6.tmsw.no>,
Terje Mathisen  <"terje.mathisen at tmsw.no"> wrote:
>This is sort of the same as the scan for first/last set bit: You might 
>very well have hw opcodes to do this efficiently, and the compiler might 
>be capable of generating it if you use the proper idiom?

That's the problem.  I don't see how to write it so the compiler will
say 'oh he's trying to do a FFS' and spit out appropriate code.

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ffs16 jgk@panix.com (Joe keane) - 2012-04-22 21:36 +0000
  Re: ffs16 Keith Thompson <kst-u@mib.org> - 2012-04-22 15:23 -0700
  Re: ffs16 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-22 20:37 -0400
    Re: ffs16 Philip Lantz <prl@canterey.us> - 2012-04-24 06:36 -0700
      Re: ffs16 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-24 20:32 -0400
        Re: ffs16 Philip Lantz <prl@canterey.us> - 2012-04-25 00:30 -0700
  Re: ffs16 Terje Mathisen <"terje.mathisen at tmsw.no"> - 2012-04-23 16:22 +0200
    Re: ffs16 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-23 21:46 -0400
      Re: ffs16 Terje Mathisen <"terje.mathisen at tmsw.no"> - 2012-04-24 14:16 +0200
        Re: ffs16 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-24 20:40 -0400
    Re: ffs16 jgk@panix.com (Joe keane) - 2012-04-24 19:06 +0000
      Re: ffs16 Terje Mathisen <"terje.mathisen at tmsw.no"> - 2012-04-25 00:38 +0200
        Re: ffs16 jgk@panix.com (Joe keane) - 2012-04-25 20:08 +0000
          Re: ffs16 "James Van Buskirk" <not_valid@comcast.net> - 2012-04-25 15:06 -0600
            Re: ffs16 "James Van Buskirk" <not_valid@comcast.net> - 2012-04-25 16:30 -0600
        Re: ffs16 jgk@panix.com (Joe keane) - 2012-04-25 21:25 +0000
          Re: ffs16 Terje Mathisen <"terje.mathisen at tmsw.no"> - 2012-04-26 01:38 +0200
            Re: ffs16 jgk@panix.com (Joe keane) - 2012-04-26 19:34 +0000
            Re: ffs16 jgk@panix.com (Joe keane) - 2012-04-26 20:41 +0000
              Re: ffs16 Terje Mathisen <"terje.mathisen at tmsw.no"> - 2012-04-27 02:47 +0200

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