Re: [Iverilog-devel] vpi_put_value

[fuyong <fuy...@gm...>]

Hi, Martin,

Finally figure out the reason. In the original example, the 1999 version I
have, intention of the test is to override the system defined function,
such as $pow. In your example, you used $my_pow() instead. Guess that in
Iverilog, system defined function calls could not be overwritten yet.
Actually I did noticed in my test with $pow(), the first $pow() called the
system pre-defined function, the second one goes to user defined function.
This is why the first $pow() passed, and the second one get error.

The version I have is:
version 11.0 (devel) (s20150603-641-ga8318db2)

Many thanks for the help!

Yong



On Sun, Oct 13, 2019 at 2:29 AM Martin Whitaker <
ic...@ma...> wrote:

> I can't reproduce the failure. We have that example in the test suite
> already - see
>
>    https://github.com/steveicarus/ivtest/blob/master/vpi/pr1693971.c
>    https://github.com/steveicarus/ivtest/blob/master/vpi/pr1693971.v
>
> Please tell us what version of iverilog you are using, and what changes
> you
> have made to the example. Just changing the type of 'result' to 'int' made
> no difference for me.
>
> fuyong wrote:
> > Hi,
> >
> > This is a test in Stuart Sutherland's PLI handbook, and it works well
> with
> > commercial tools. In Iverilog, we can have compile done, but run time
> show:
> >
> > $pow(2, 3) returns 8
> > Unsupported format 6.
> > vvp: vpi_tasks.cc:179:virtual __vpiHandle*
> > sysfunc_real::vpi_put_value(p_vpi_value, int): Assertion `0` failed.
> >
> > There are two $pow() calls .First one returns correct result, second one
> > failed. with vpi_print, we find seems like the first pow() did not even
> > called  our defined function (might be using the $pow in build-in
> $pow()?).
> > Any way, "result" is defined as int, not sure why the assertion is
> trigger
> > in run time.
> >
> >
> >
> > === Verilog side:
> >    initial
> >      begin
> >        a = 1;
> >        b = 0;
> >        #1 $display("$pow(2,3) returns %d", $pow(2,3));
> >        #1 result = $pow(a,b);
> >        #1 $display("$pow(a,b) returns %d (a=%d b=%d)", result, a, b);
> >
> > === C side:
> >
> >    tf_data.type        = vpiSysFunc;
> >    tf_data.sysfunctype = vpiSysFuncSized;
> >    tf_data.tfname      = "$pow";
> >    tf_data.calltf      = PLIbook_PowCalltf;
> >    tf_data.compiletf   = PLIbook_PowCompiletf;
> >    tf_data.sizetf      = PLIbook_PowSizetf;
> >    vpi_register_systf(&tf_data);
> >
> >
> > int PLIbook_PowCalltf(char *user_data)
> > {
> >    s_vpi_value value_s;
> >    vpiHandle   systf_handle, arg_itr, arg_handle;
> >    int         base, exp, result;
> >
> >    systf_handle = vpi_handle(vpiSysTfCall, NULL);
> >    arg_itr = vpi_iterate(vpiArgument, systf_handle);
> >    if (arg_itr == NULL) {
> >      vpi_printf("ERROR: $pow failed to obtain systf arg handles\n");
> >      return(0);
> >    }
> >
> >    /* read base from systf arg 1 (compiletf has already verified) */
> >    arg_handle = vpi_scan(arg_itr);
> >    value_s.format = vpiIntVal;
> >    vpi_get_value(arg_handle, &value_s);
> >    base = value_s.value.integer;
> >
> >    /* read exponent from systf arg 2 (compiletf has already verified) */
> >    arg_handle = vpi_scan(arg_itr);
> >    vpi_free_object(arg_itr); /* not calling scan until returns null */
> >    vpi_get_value(arg_handle, &value_s);
> >    exp = value_s.value.integer;
> >
> >    /* calculate result of base to power of exponent */
> >    result = (int)pow( (double)base, (double)exp );
> >
> >    /* write result to simulation as return value $pow */
> >    value_s.value.integer = result;
> >    vpi_put_value(systf_handle, &value_s, NULL, vpiNoDelay);
> >    return(0);
> > }
> >
> >
> >
> >
> >
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> >
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