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Re: volatile in struct member

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Ben Bacarisse <ben.usenet@bsb.me.uk> writes:

> But I suspect the question is more about the placement of the keyword.
> I'd put the volatile on the object declaration:
>
>   struct small { int i; };
>   volatile struct small sm;

But one could easily imagine a struct like

struct register
{
   volatile int * address;
   int last_written_value;
}

void write_reg(struct register*reg,int val)
{
  *reg->address = val;
  last_written_value = val;
}

int read_reg(struct register*reg,int val)
{
  return reg->last_written_value;
}

I wouldn't need to have the cached value marked as volatile (though in a
trivial example like this it would make little difference to performance).

I've programmed FPGAs with "write only" registers like this.

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volatile in struct member Thiago Adams <thiago.adams@gmail.com> - 2016-09-30 04:52 -0700
  Re: volatile in struct member Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-30 05:50 -0700
    Re: volatile in struct member Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 14:42 +0100
      Re: volatile in struct member Gareth Owen <gwowen@gmail.com> - 2016-09-30 22:09 +0100
        Re: volatile in struct member Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 22:24 +0100
  Re: volatile in struct member Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 14:29 +0100
    Re: volatile in struct member David Brown <david.brown@hesbynett.no> - 2016-09-30 16:22 +0200
      Re: volatile in struct member Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 15:51 +0100
        Re: volatile in struct member David Brown <david.brown@hesbynett.no> - 2016-09-30 17:07 +0200
    Re: volatile in struct member Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-08 15:48 -0700
  Re: volatile in struct member David Brown <david.brown@hesbynett.no> - 2016-09-30 15:36 +0200
    Re: volatile in struct member Thiago Adams <thiago.adams@gmail.com> - 2016-09-30 06:47 -0700
      Re: volatile in struct member James Kuyper <jameskuyper@verizon.net> - 2016-09-30 12:53 -0400
        Re: volatile in struct member supercat@casperkitty.com - 2016-09-30 10:18 -0700
          Re: volatile in struct member raltbos@xs4all.nl (Richard Bos) - 2016-09-30 20:57 +0000
            Re: volatile in struct member supercat@casperkitty.com - 2016-09-30 14:46 -0700
        Re: volatile in struct member Thiago Adams <thiago.adams@gmail.com> - 2016-09-30 10:22 -0700
          Re: volatile in struct member jameskuyper@verizon.net - 2016-09-30 14:08 -0700

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