Forums

Verilog VPI

Started by slawc October 10, 2005
Hi,

I'm developing in verilog (Xilinx web pack with Modelsim XE). I came to 
the point I have to use some external c software for generating some 
signals. It's not mine though but I have the source that is using VPI. 
The problem is that this external code is using internal static 
variables for storing data between calls (y[n] = f(x,t,y[n-1])) from 
verilog and while using only one instance like this

always @(posedge clk)
out = $gen(parameters)

it works fine. But now I need to use two or more instances at the same 
time like this:

always @(posedge clk)
out1 = $gen(parameters)
out2 = $gen(parameters)
.
.
outn = $gen(parameters)

Because of internal static variables used in gen this is not working any 
more. I tried to save data like in workarea example (chapter 6) 
(http://www.sutherland.com/pli_book_examples.html) but it doesn't work: 
every time gen function is called different handler is passed to the 
function and diferent workarea is created on the stack. How can I get 
module handle that called my C function so I can save data between calls 
from verilog?

Thanks,
Slawc