Re: [Iverilog-devel] vpi_put_value

[Martin W. <ic...@ma...>]

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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