Re: Academic Q: Why doesn't Quartus Synthesis Allow Some Restricted Classes?

Altera_Forum · ‎12-23-2017

Was pleased to discover SV supports scalable tasks/functions to the extent that if you bury it in a class you can set the 'type' by parameter.

Why then can't this be synthesized? For example, why can't I synthesize this:

    class generic# (type T=logic);
        static function int find_first_msb(input T vector); 
            for(int i=$bits(vector)-1;i>=0;i--)
                if(vector) 
                    return i;
            return -1;
        endfunction//find_first_msb
    endclass
    ...
    msb  = generic#(uint32)::find_first_msb(decimal);

Rather, I have to create a fixed-width version.

    function int find_first_msb(input uint32 vector);
        for(int i=$bits(vector)-1;i>=0;i--)
            if(vector) 
                return i;
        return -1;
    endfunction//find_first_msb

There's nothing to prevent this limited (but useful!) functionality from being synthesized.

~SysTom

Altera_Forum · ‎12-23-2017

I don't think classes are supported for syntheses at all.

Altera_Forum · ‎12-23-2017

Static class methods are synthesizable in other tools, but apparently not in the tool you are using. They allow you to have parameterizable functions.

Altera_Forum · ‎12-28-2017

Thanks Tricky, dave_59.

Yep, the tool is Quartus.

Thanks again, Tom