Re: Cortex-M: share an int between two tasks

From	Hans-Bernhard Bröker <HBBroeker@t-online.de>
Newsgroups	comp.arch.embedded
Subject	Re: Cortex-M: share an int between two tasks
Date	2020-03-18 17:37 +0100
Message-ID	<hdf12vFmjf4U1@mid.dfncis.de> (permalink)
References	<r4g5sc$8jr$1@dont-email.me> <r4gdi2$tn$1@dont-email.me> <r4skvb$tkq$1@dont-email.me>

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Am 18.03.2020 um 09:09 schrieb pozz:

> I think the access could be volatile only in the loop and not in 
> set_waiting_period:

You could do that, but you absolutely should not.

You make the _variable_ volatile, and that's that.

>      volatile uint32_t *vwait_period = (volatile uint32_t *)&wait_period;

Just looking at that line should tell you that this cannot possibly be 
the right way to do anything.

The primary rule about explicitly casting pointers in C code is: don't 
do it.  All the evidently safe casts are already performed implicitly by 
the compiler.  The perceived need for less safe ones almost invariably 
results from an incorrect design decision a few steps earlier.

Thread

Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-13 15:38 +0100
  Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-13 17:49 +0100
    Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-18 09:09 +0100
      Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 09:17 +0100
      Re: Cortex-M: share an int between two tasks Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2020-03-18 17:37 +0100
        Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 19:23 +0100
    Re: Cortex-M: share an int between two tasks Les Cargill <lcargill99@comcast.com> - 2020-03-22 13:42 -0500
      Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-22 21:45 +0100
      Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-22 20:50 -0400
        Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-23 09:09 +0100
          Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-23 08:00 -0400
            Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-23 14:21 +0100
              Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-03-25 09:55 +1100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-30 16:07 +0200
                Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-03-31 09:02 +1100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-31 10:57 +0200
                Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-04-01 12:05 +1100
                Re: Cortex-M: share an int between two tasks Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-03-30 17:49 +0300
                Re: Cortex-M: share an int between two tasks kegs@provalid.com (Kent Dickey) - 2020-05-19 00:34 -0500
                Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-05-19 17:40 +1000
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-05-19 12:00 +0200
                Re: Cortex-M: share an int between two tasks Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-05-19 13:48 +0100
  Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-18 09:20 +0100
    Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 10:06 +0100
      Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-18 10:59 +0100
        Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 11:48 +0100
          Re: Cortex-M: share an int between two tasks upsidedown@downunder.com - 2020-03-18 20:37 +0200
            Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 21:24 +0100
              Re: Cortex-M: share an int between two tasks Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-03-19 14:05 +0200
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 13:16 +0100
                Re: Cortex-M: share an int between two tasks Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-03-19 14:27 +0200
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 14:13 +0100
            Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 08:03 +0100
              Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 09:10 +0100
              Re: Cortex-M: share an int between two tasks upsidedown@downunder.com - 2020-03-19 12:51 +0200
          Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 07:40 +0100
            Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 09:38 +0100
              Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 11:26 +0100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 12:12 +0100
                Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 15:31 +0100
                Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-23 09:22 +0100
                Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-23 08:10 -0400
                Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-23 13:47 +0100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-23 14:31 +0100
                Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-23 13:50 -0400
            Re: Cortex-M: share an int between two tasks Niklas Holsti <niklas.holsti@tidorum.invalid> - 2020-03-19 12:27 +0200
              Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 11:45 +0100
                Re: Cortex-M: share an int between two tasks upsidedown@downunder.com - 2020-03-19 13:27 +0200
    Re: Cortex-M: share an int between two tasks antispam@math.uni.wroc.pl - 2020-03-18 16:24 +0000

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