How to set the subroutine permissions for the dot access of an algorithm input?

[at91rm9200]

Hello Sylvain,

I am trying to set the subroutine permission to access "a1.value" in the algorithm "a" without success.

algorithm a(input uint1 value) <autorun>
{
   uint1 local_value = uninitialized;

   while (1) {
      local_value = value;
   }
}

algorithm main(output uint5 leds, inout uint8 pmod)
{
   a a1;

   subroutine s(writes _a1_value) {
                   //  ^ this should not be here

      a1.value = 1;
   }

   while (1) {
      () <- s <- ();
   }
} 

Without any permissions, the compiler realizes: "variable '_a1_value' is written by subroutine 's' without explicit permission". So I tried it with the permission "writes _a1_value", but this leads to the error: "^ this should not be here". Is this a bug?

Regards, Bernd.

[sylefeb]

Hello Bernd,

There is a special calls keyword, which applies both to other subroutines and algorithm instances. I made an example here.

[at91rm9200]

Hello Sylvain,

thank you. The permission "calls" indeed works. I would not have guessed this, since I am using the dot access to the (auto running) algorithm and do not call it (I think).

Regards, Bernd.

[sylefeb]

That is an excellent point, calls does not really match the usage here. I wonder, shall I add an extra (equivalent) keyword uses?

Regards, Sylvain

[at91rm9200]

Maybe the permission uses would fit a bit better than calls in this case.

But I am wondering, why the permission writes should not be the right one. Exactly this tells the Silice compiler, if I intentional omit the permission completely in the subroutine declaration: variable '_a1_value' is written by subroutine 's' without explicit permission.

In my opinion, the subroutine should be declared like:

subroutine s(writes a1.value)

But I could be totally wrong.

[sylefeb]

Indeed, it does make sense -- that might be either of reads/writes/readwrites, perhaps not having to specify each member, e.g. simply writes a1. Let's keep the issue open and I'll come back to it - thank you!

[at91rm9200]

Hello Sylvain,

compiling the following code with the latest draft version produces a warning in line 7:

unit main(output uint5 leds, inout uint8 pmod)
{
   algorithm
   {
      subroutine sub(readwrites pmod)
      {
         pmod.o = 33; // <----- [warning] variable 'pmod_o' is written by subroutine 'sub' without explicit permission
      }

      while (1) {
         () <- sub <- ();
      }

   }
}

How can I avoid the warning?

With an earlier Silice version it was possible to declare the subroutine as follows:

subroutine sub(readwrites pmod_o)

But this leads now to an error: cannot find referenced identifier 'pmod_o'...

Regards, Bernd.

Edit 10.04. I mixed up master with draft version. The warning occurs with the current master version. I did not check the draft version.

[sylefeb]

Hi Bernd, thanks for the report, will look into it.

[sylefeb]

This issue should be fixed in draft branch.