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Accessing Packed Arrays using Tcl Interface

GaneshAMBA

I am exploring options to access and modify the contents of a packed array in the simulation hierarchy, with the aim of replicating some VPI functionality using the Tcl scripting interface.

I have a small test-case to clarify the issue that I am facing:

The design has a packed array defined as below:

logic [5:0][5:0] packed_array_test;

With vpi_put_value, packed_array_test can be accessed as a single-dimensional array of [35:0], and it is possible to deposit, say, any 32-bit value to packed_array_test[31:0]

Is it possible to get a similar functionality with the Tcl interface?

I have currently tried the following:

xcelium> value %b TB.DUT0.packed_array_test
36'b000000000001000000000000000001000000
xcelium> force TB.DUT0.packed_array_test = 36'h12345FFFF
xcelium> value %b TB.DUT0.packed_array_test
36'b000100100011010001011111111111111111
xcelium> force TB.DUT0.packed_array_test[31:0] = 32'hFFFF1234
xmsim: *E,PINRNG: Index value out of range: [31:0].

It appears that the force command will either work on the full packed array, or, if accessing a particular set of bits, with all the dimensions explicitly specified.

Do the Tcl force / value commands have any options that would allow for packed array access functionality similar to vpi_put_value / vpi_get_value?

  • TCL cannot access [31:0] because the array is defined as [5:0][5:0]. 

    xcelium> force TB.DUT0.packed_array_test[3][5:0] = 6'hFF
    xcelium> force TB.DUT0.packed_array_test[2][5:0] = 6'hFF
    xcelium> force TB.DUT0.packed_array_test[1][5:0] = 6'h12
    xcelium> force TB.DUT0.packed_array_test[0][5:0] = 6'h34

    Or 

    xcelium> force TB.DUT0.packed_array_test = 32''hFFFF1234

    Tim

  • in reply to tpylant

    Tim,

    Thank you for the response. I understand the first solution, but it is something not readily implementable in my current setup. The second solution doesn't work always because I might want to access packed_array_test[35:32] alone - something that IS possible with a single call to vpi_put_value / vpi_get_value.

    I was looking to avoid multiple force statements, and also parsing of the 'describe' command output - as they both complicate the overall environment in which the scheme has to work. The input to the Tcl script is just the hierarchical path to the signal and its unrolled packed dimensions - now, it looks like I have to find a way to get the original dimensions of the signal definition from within the Tcl script.

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