Boolean Operations on Fields and Signals

[willy134]

Looking through the compiler examples and test cases, I never could find an example of the boolean operations.

I was looking for something like this

reg {
    field {
       desc="Write 0x9A to unlock register"
       sw=rw;
       hw=na;
     } unlock[31:16];
    field {
      desc="locked field";
      sw=rw;
      hw=r;
    } locked[7:0];
    locked->swwe = unlock->next == 0x9A || unlock == 0x9A;
}

The hope is that the boolean == and || operations actually result in a boolean value for the swwe signal in this case. I also see use cases where a register is reset when a magic key is written to it (think watchdog timer).

Are there any known examples of these boolean operations? Does my interpretation of the spec make sense? I could create similar things with the external swwe signal, but it would lack the ability to use the next reference.

The error I am seeing when I try this is:
fatal: Left and right operands of expression are not compatible types

[amykyta3]

Currently, this compiler only supports constant expressions that resolve to an integral value or a single reference (See https://systemrdl-compiler.readthedocs.io/en/stable/known_issues.html#property-assignments-using-references-shall-be-constant)

Eventually I may support this by preserving non-constant expressions as an AST so that developers can transcribe them to the output language. This would likely be part of #58 since the concepts are closely related.