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Groups > comp.lang.c > #126304
| From | scott@slp53.sl.home (Scott Lurndal) |
|---|---|
| Subject | Re: Count string in string with loop increase 2, why is this not faster? |
| Newsgroups | comp.lang.c |
| References | (6 earlier) <B30eC.488069$1x.140608@fx30.am4> <c8ccaab5-0429-4a03-8cb2-a8c23c40bb29@googlegroups.com> <gn1eC.1616836$OX.1427743@fx47.am4> <Kz1eC.1462$nY2.602@fx28.iad> <iR2eC.760204$pP1.434568@fx21.am4> |
| Message-ID | <M_3eC.5140$vP3.694@fx15.iad> (permalink) |
| Organization | UsenetServer - www.usenetserver.com |
| Date | 2018-02-05 21:27 +0000 |
bartc <bc@freeuk.com> writes: >On 05/02/2018 18:41, Scott Lurndal wrote: >> bartc <bc@freeuk.com> writes: >>> On 05/02/2018 17:44, Bart Smissaert wrote: >>>> So, are you saying forget about gaining some (little) time by skipping the even bytes? I think it is best to stick with only one, the function called SQLITE_API int sqlite3_CountStringInString. >>> >>> I think that the char-based version that skipped a byte at a time was >>> slowing things down. The one that skipped two bytes is now equivalent to >>> the function taking wchar_t strings that skip a char (= 2 bytes) at a time. >>> >>> So using wchar_t originally would have been better. >>> >>> I can't see any simple way of making this faster... >> >> Use PCMPEQW to compare a vector of wchar_t's against a vector of the first >> character of the search string and compare from there. Or, if the search >> string is less than 8 wchar_t (128 bits), use PCMPEQW with a sliding comparision >> against the source string. >> > >... in C. > >Isn't this the job of memcmp? > >But I've tried a couple of tests and managed 40-60% faster than gcc-O3 >using ordinary inline ASM. (And that's within the framework of my non-C >language and poor compiler, comparing a 16-bit word at a time as I can't >remember how to use string compare instructions.) > >How did you fare with PCMPEQW? http://www.alfredklomp.com/programming/sse-strings/
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Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 00:00 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 11:29 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 03:37 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 12:29 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 04:37 -0800
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-03 13:41 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 06:38 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 15:13 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 15:19 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 07:41 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 11:38 -0500
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 13:50 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-03 11:34 +0000
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 11:32 -0500
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-03 16:41 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 09:02 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 09:06 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 12:39 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 11:56 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 19:54 -0500
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-03 18:00 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 01:53 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 13:23 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 11:11 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 14:48 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 12:17 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 21:53 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 14:35 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 23:32 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-05 06:26 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 16:59 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-05 09:44 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 18:28 +0000
Re: Count string in string with loop increase 2, why is this not faster? scott@slp53.sl.home (Scott Lurndal) - 2018-02-05 18:41 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 20:08 +0000
Re: Count string in string with loop increase 2, why is this not faster? scott@slp53.sl.home (Scott Lurndal) - 2018-02-05 21:27 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 22:04 +0000
Re: Count string in string with loop increase 2, why is this not faster? scott@slp53.sl.home (Scott Lurndal) - 2018-02-05 22:38 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 01:34 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 06:39 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 18:07 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 12:34 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 21:12 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 13:42 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 16:43 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 01:10 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-06 18:47 -0800
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-07 15:13 +0100
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 14:48 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 17:13 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 17:27 +0000
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-07 17:01 +0100
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 02:00 -0800
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 12:02 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 14:46 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 13:56 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 11:17 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 23:59 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 05:10 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 11:01 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 14:24 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 14:44 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 22:59 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-07 15:20 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 23:31 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 15:32 -0800
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-07 16:05 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-05 15:29 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 17:41 -0500
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 23:11 +0000
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 23:45 -0500
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-04 15:11 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 23:37 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-04 18:08 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 23:12 -0500
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-05 13:08 +0100
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-05 08:24 -0500
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-05 14:39 +0100
Re: Count string in string with loop increase 2, why is this not faster? Robert Wessel <robertwessel2@yahoo.com> - 2018-02-05 10:37 -0600
Re: Count string in string with loop increase 2, why is this not faster? supercat@casperkitty.com - 2018-02-05 13:52 -0800
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-05 22:29 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-05 09:01 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 18:44 +0000
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-06 10:42 +0100
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-06 11:17 +0000
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-06 08:40 -0500
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 14:08 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-06 14:42 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-06 12:35 -0800
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-06 23:04 +0100
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 17:35 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 14:38 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 17:57 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 15:22 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 12:19 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 16:42 -0500
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-03 13:38 -0800
Re: Count string in string with loop increase 2, why is this not faster? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-02-03 22:03 +0000
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