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| From | "James Harris" <james.harris.1@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Sequence points and commit to memory |
| Date | 2015-05-17 18:24 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <mjaipk$d77$1@dont-email.me> (permalink) |
| References | (3 earlier) <ovpcla11flbendmoa1vimlk2ht0ll76e5t@4ax.com> <mj6ppc$669$1@dont-email.me> <2ordlatkut0h026ruk5i7fp685b6v3gj2q@4ax.com> <mj6s01$cbi$1@dont-email.me> <4ingla5ndd1krtpomnc6q6cp1g2rlt6ffp@4ax.com> |
"Robert Wessel" <robertwessel2@yahoo.com> wrote in message news:4ingla5ndd1krtpomnc6q6cp1g2rlt6ffp@4ax.com... > On Sat, 16 May 2015 08:36:36 +0100, "James Harris" > <james.harris.1@gmail.com> wrote: > >>"Robert Wessel" <robertwessel2@yahoo.com> wrote in message >>news:2ordlatkut0h026ruk5i7fp685b6v3gj2q@4ax.com... >>> On Sat, 16 May 2015 07:58:54 +0100, "James Harris" >>> <james.harris.1@gmail.com> wrote: >>> ... >>>>Forcing a read is only necessary if something else could have >>>>changed >>>>the value behind our back. >>> >>> >>> Yes, but you need to force the read in those other modules who >>> *will* >>> have that value "changed behind their backs". >> >>Not in this case. That would be true only if their activations >>persist, >>I would have thought, i.e. if the two were running concurrently. For a >>function which starts, executes and stops and only reads the value >>once >>(or reads it multiple times knowing that it cannot be changed while >>this >>function is executing) I don't see that there would be a problem and >>that is the case here. The interrupt handler would read some of these >>values knowing that from the start of the interrupt handler's >>execution >>until it returns the main program will not be able to modify the value >>because it will not be executing concurrently with the interrupt >>handler. > > > This may be due to my having lost track of exactly which case we're > trying to discuss here, but... I know how you feel! > Assuming the interrupt handler is the one to update the field, it > would be the interrupted routine that would need to re-read the value. The case I was thinking of was the converse: the main routine making the updates and the interrupt handler just reading. Nothing would change the value while the interrupt handler was running. >>That said, if I went down the volatile route I would probably declare >>it >>as volatile in both. That would achieve the same effect and be safer >>against future changes. > > > Is it actually legal to *not* declare them as both with the same > volatility? I don't know. There seem to be lots of gotchas. James
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Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-14 11:43 +0100
Re: Sequence points and commit to memory Richard Heathfield <rjh@cpax.org.uk> - 2015-05-14 12:02 +0100
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-14 13:39 +0200
Re: Sequence points and commit to memory Richard Heathfield <rjh@cpax.org.uk> - 2015-05-14 13:18 +0100
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-14 23:11 +0200
Re: Sequence points and commit to memory Stephen Sprunk <stephen@sprunk.org> - 2015-05-14 09:06 -0500
Re: Sequence points and commit to memory Siri Cruz <chine.bleu@yahoo.com> - 2015-05-14 08:35 -0700
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-14 10:23 -0700
Re: Sequence points and commit to memory Siri Cruz <chine.bleu@yahoo.com> - 2015-05-14 10:44 -0700
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-14 11:09 -0700
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-14 12:58 -0700
Re: Sequence points and commit to memory Morris Dovey <mrdovey@iedu.com> - 2015-05-14 16:31 -0500
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-14 17:24 -0700
Re: Sequence points and commit to memory Morris Dovey <mrdovey@iedu.com> - 2015-05-14 20:18 -0500
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-15 09:34 +0200
Re: Sequence points and commit to memory Morris Dovey <mrdovey@iedu.com> - 2015-05-15 10:18 -0500
Re: 'register' attribute (was: Sequence points and commit to memory) Morris Dovey <mrdovey@iedu.com> - 2015-05-16 01:26 -0500
Re: 'register' attribute David Brown <david.brown@hesbynett.no> - 2015-05-17 00:02 +0200
Re: 'register' attribute Morris Dovey <mrdovey@iedu.com> - 2015-05-16 19:29 -0500
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-15 09:52 -0700
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-15 13:27 -0400
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-15 10:50 -0700
Re: Sequence points and commit to memory Morris Dovey <mrdovey@iedu.com> - 2015-05-15 12:32 -0500
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-14 23:23 +0200
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-15 09:42 -0700
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-15 13:13 -0400
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-16 08:32 -0700
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-15 10:35 -0700
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-15 11:08 -0700
Re: Sequence points and commit to memory Robert Wessel <robertwessel2@yahoo.com> - 2015-05-15 16:40 -0500
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-16 08:48 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-15 21:46 +0100
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-16 08:56 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-16 19:35 +0100
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-18 09:49 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-19 09:04 +0100
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-19 08:42 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-14 22:00 +0100
Re: Sequence points and commit to memory Siri Cruz <chine.bleu@yahoo.com> - 2015-05-14 14:26 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-14 22:33 +0100
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-14 23:38 +0200
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-14 23:04 +0100
Re: Sequence points and commit to memory Stephen Sprunk <stephen@sprunk.org> - 2015-05-15 13:09 -0500
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-15 21:56 +0100
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-15 17:30 -0400
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-16 07:51 +0100
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-16 22:10 -0400
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 00:25 +0200
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-18 18:55 -0400
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 09:10 +0200
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-19 12:05 -0400
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 18:42 +0200
Re: Sequence points and commit to memory Stephen Sprunk <stephen@sprunk.org> - 2015-05-16 16:33 -0500
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 00:27 +0200
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-18 19:05 -0400
Re: Sequence points and commit to memory glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-19 00:09 +0000
Re: Sequence points and commit to memory Richard Heathfield <rjh@cpax.org.uk> - 2015-05-19 01:11 +0100
Re: Sequence points and commit to memory Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-23 07:02 -0700
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-18 23:21 -0400
Re: Sequence points and commit to memory glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-19 06:25 +0000
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 08:58 +0200
Re: Sequence points and commit to memory glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-19 23:20 +0000
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-20 12:31 +0200
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-19 12:10 -0400
Re: Sequence points and commit to memory glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-19 23:24 +0000
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 09:05 +0200
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-19 08:37 -0700
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-19 12:14 -0400
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 19:02 +0200
Re: Sequence points and commit to memory Robert Wessel <robertwessel2@yahoo.com> - 2015-05-15 16:46 -0500
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-17 00:20 +0200
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-17 18:19 +0100
Re: Sequence points and commit to memory Philip Lantz <prl@canterey.us> - 2015-05-17 16:11 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-18 08:30 +0100
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-18 10:31 -0700
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-18 11:11 -0700
Re: Sequence points and commit to memory David Kleinecke <dkleinecke@gmail.com> - 2015-05-19 09:37 -0700
Re: Sequence points and commit to memory Ian Collins <ian-news@hotmail.com> - 2015-05-19 17:40 +1200
Re: Sequence points and commit to memory Morris Dovey <mrdovey@iedu.com> - 2015-05-19 01:31 -0500
Re: Sequence points and commit to memory Ian Collins <ian-news@hotmail.com> - 2015-05-19 20:38 +1200
Re: Sequence points and commit to memory Morris Dovey <mrdovey@iedu.com> - 2015-05-19 10:50 -0500
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 00:46 +0200
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 00:35 +0200
Re: Sequence points and commit to memory Robert Wessel <robertwessel2@yahoo.com> - 2015-05-15 16:42 -0500
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-16 07:58 +0100
Re: Sequence points and commit to memory Robert Wessel <robertwessel2@yahoo.com> - 2015-05-16 02:18 -0500
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-16 08:36 +0100
Re: Sequence points and commit to memory Robert Wessel <robertwessel2@yahoo.com> - 2015-05-17 04:31 -0500
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-17 18:24 +0100
Re: Sequence points and commit to memory David Brown <david.brown@hesbynett.no> - 2015-05-19 00:55 +0200
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-14 11:26 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-14 22:07 +0100
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-14 14:22 -0700
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-14 22:36 +0100
Re: Sequence points and commit to memory Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-22 08:16 -0700
Re: Sequence points and commit to memory Keith Thompson <kst-u@mib.org> - 2015-05-22 11:31 -0700
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-15 00:05 -0400
Re: Sequence points and commit to memory "James Harris" <james.harris.1@gmail.com> - 2015-05-15 22:25 +0100
Re: Sequence points and commit to memory James Kuyper <jameskuyper@verizon.net> - 2015-05-15 17:56 -0400
Re: Sequence points and commit to memory Nobody <nobody@nowhere.invalid> - 2015-05-17 10:04 +0100
Re: Sequence points and commit to memory Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-24 08:11 -0700
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