Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > comp.lang.c > #97990

Re: Counted strings

From Robert Spanjaard <spamtrap@arumes.com>
Newsgroups comp.lang.c
Subject Re: Counted strings
Date 2016-12-04 20:19 +0100
Organization Aioe.org NNTP Server
Message-ID <o21q7d$uoi$1@gioia.aioe.org> (permalink)
References <o1viji$9d6$1@dont-email.me> <o21cu9$b7k$1@dont-email.me>

Show all headers | View raw


On 04-12-16 16:33, David Brown wrote:
> > What are your ideas about counted strings?
>>
>> How could it be done?
>
> I would be inclined to simplify to only two possible choices - an 7-bit
> length that covers most small strings, and a 31-bit length that covers
> any string (data that is more than 2GB is size is not a "string").
>
> You could use the LSB of the first byte of the string to determine if
> the rest of the byte gives the 7-bit length, or if the rest of the first
> 4 bytes gives the 31-bit length.  Distinguishing between the two is just
> a bit test, and decoding the length is a simple shift instruction
> (especially if you have a little-endian platform with 32-bit unsigned
> ints and misaligned load support).
>
> I think there is little to be gained by supporting 16-bit length fields.

That depends on what type of data you're going to count. For normal text
(books, papers, etc), 16 bit seems to be a sensible length. I never
encountered a single paragraph longer than 65535 characters, while
paragraphs longer than 255 characters are quite common (seems to be between
15 and 20% based on a quick scan of a couple of random books). In those 
cases, Jacob's original approach produces the smallest amount of counting 
data with about 80% 1-byte values and 20% 2-byte values.

-- 
Robert Spanjaard

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread


Thread

Counted strings jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-03 23:58 +0100
  Re: Counted strings supercat@casperkitty.com - 2016-12-03 15:40 -0800
  Counted stringsl Thiago Adams <thiago.adams@gmail.com> - 2016-12-03 15:40 -0800
  Re: Counted strings BartC <bc@freeuk.com> - 2016-12-04 00:20 +0000
  Re: Counted strings Richard Damon <Richard@Damon-Family.org> - 2016-12-03 21:26 -0500
    Re: Counted strings jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-04 18:11 +0100
    Re: Counted strings Mark Storkamp <mstorkamp@yahoo.com> - 2016-12-04 19:25 -0600
  Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-03 18:57 -0800
  Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 16:33 +0100
    Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-04 07:52 -0800
      Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 17:10 +0100
        Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-04 10:14 -0800
          Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 20:20 +0100
            Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-04 16:49 -0800
              Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 10:40 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 05:51 -0800
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 16:10 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 07:38 -0800
                Re: Counted strings Melzzzzz <mel@zzzzz.com> - 2016-12-05 16:56 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 08:04 -0800
                Re: Counted strings Melzzzzz <mel@zzzzz.com> - 2016-12-05 17:16 +0100
                Re: Counted strings Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-05 16:12 -0500
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 13:24 -0800
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 10:53 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 03:52 -0800
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 13:32 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 04:48 -0800
                Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 13:42 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 05:16 -0800
                Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 14:39 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 05:24 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 05:41 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 05:47 -0800
                Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 14:48 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 05:54 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 06:21 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 06:24 -0800
                Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 18:06 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 10:19 -0800
                Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 19:45 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 11:10 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 12:58 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 14:08 -0800
                Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-06 11:25 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 05:28 -0800
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 16:21 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 07:29 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 07:39 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 08:32 -0800
                Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 08:32 -0800
                Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 16:28 +0000
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 08:34 -0800
                Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 18:27 +0000
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 10:36 -0800
                Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 08:19 +1300
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 11:22 -0800
                Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 08:26 +1300
                Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 19:36 +0000
                Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 08:41 +1300
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 11:48 -0800
                Re: Counted strings Thiago Adams <thiago.adams@gmail.com> - 2016-12-05 11:59 -0800
                Re: Counted strings jameskuyper@verizon.net - 2016-12-05 12:12 -0800
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 12:18 -0800
                Re: Counted strings jameskuyper@verizon.net - 2016-12-05 13:17 -0800
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 13:29 -0800
                Re: Counted strings jameskuyper@verizon.net - 2016-12-05 15:37 -0800
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 15:43 -0800
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 13:40 +0100
                Re: Counted strings "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-06 12:00 -0500
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 10:09 -0800
                Re: Counted strings Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-06 13:33 -0500
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 21:24 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 12:56 -0800
                Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-05 12:22 -0800
                Re: Counted strings supercat@casperkitty.com - 2016-12-05 08:36 -0800
                Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 17:31 +0000
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 22:07 +0100
                Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 10:14 +1300
                Re: Counted strings Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-05 22:11 +0000
                Re: Counted strings BartC <bc@freeuk.com> - 2016-12-06 02:13 +0000
                Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 21:57 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 13:01 -0800
                Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 21:22 +0000
                Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 10:25 +1300
                Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 21:36 +0000
                Re: Counted strings jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-05 22:33 +0100
                Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 17:03 -0500
    Re: Counted strings supercat@casperkitty.com - 2016-12-04 08:57 -0800
    Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-04 20:19 +0100
      Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 20:24 +0100
        Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-04 20:37 +0100
          Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 21:04 +0100
            Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-04 21:22 +0100
              Re: Counted strings BartC <bc@freeuk.com> - 2016-12-04 22:37 +0000
              Re: Counted strings David Thompson <dave.thompson2@verizon.net> - 2016-12-10 22:42 -0500
                Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-10 23:17 -0800
                Re: Counted strings Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 11:48 +0000
                Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-11 04:40 -0800
                Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-11 10:56 +0100
      Re: Counted strings Robert Wessel <robertwessel2@yahoo.com> - 2016-12-05 15:47 -0600
        Re: Counted strings Gareth Owen <gwowen@gmail.com> - 2016-12-05 22:01 +0000
          Re: Counted strings Robert Wessel <robertwessel2@yahoo.com> - 2016-12-05 22:28 -0600
        Re: Counted strings "Chris M. Thomasson" <invalid@invalid.invalid> - 2016-12-05 20:18 -0800
        Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 11:05 +0100
  Re: Counted strings luser droog <luser.droog@gmail.com> - 2016-12-04 13:13 -0800
  Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-05 09:30 -0800
    Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-05 09:41 -0800
      Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-06 11:19 -0800
        Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-06 11:44 -0800
  Re: Counted strings Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-10 10:29 -0800
    Re: Counted strings supercat@casperkitty.com - 2016-12-10 11:08 -0800

csiph-web