Re: gEDA-user: icarus, fork, and recursive tasks

[DJ Delorie <dj@xxxxxxxxxxx>]

> What you want to do is make mcu_cson mcu_wron etc registers.

hmmmm...

Those values are clock counts programmed into the MCU's bus control
registers.  There's a different count for turning the signal on vs
turning it off, and the counts depend on the address as well.  I'm
modelling a chip select-style addr/data bus, so the timing parameters
depend on which memory area is being addressed.

This is in the testbench, not the FPGA code.

Here's a bigger chunk of code.  BCLK is the bus clock; all things
happen on a rising edge, and bclk1 and bclk2 are tasks that wait for
the two edges to happen.  twait() is supposed to wait for the right
number of bclk edges.

initial
  begin
     cson[1] = 0;
     csrwait[1] = 6;
     rdon[1] = 2;
     csroff[1] = 1;
     wdon[1] = 0;
     wron[1] = 0;
     cswwait[1] = 6;
     wdoff[1] = 1;
     cswoff[1] = 1;
     
     cson[3] = 0;
     rdon[3] = 1;
     csrwait[3] = 2;
     csroff[3] = 1;
     wdon[3] = 0;
     wron[3] = 0;
     cswwait[3] = 0;
     wdoff[3] = 1;
     cswoff[3] = 1;
     
     cson[4] = 0;
     rdon[4] = 1;
     csrwait[4] = 2;
     csroff[4] = 1;
     wdon[4] = 0;
     wron[4] = 0;
     cswwait[4] = 0;
     wdoff[4] = 1;
     cswoff[4] = 1;
  end

reg mcu_cson_running = 0;
task mcu_cson;
   input [23:0] address;
   begin
      mcu_cson_running = 1;
      
      twait(cson[cs]);
       case (address[23:20])
	 3: cs3 = 0;
	 4: cs4 = 0;
       endcase
      mcu_cson_running = 0;
   end
endtask
      
reg mcu_cswoff_running = 0;
task mcu_cswoff;
   input [23:0] address;
   begin
      mcu_cswoff_running = 1;
      twait(cswoff[cs]);
      cs3 = 1;
      cs4 = 1;
      mcu_cswoff_running = 0;
   end
endtask

task mcu_write;
   input [23:0] address;
   input [15:0] data;
   input [1:0] 	bhl;
   begin
      cs = address[23:20];

      bclk1;
      a = address;
      d_val = data;
      rd = 1;
      mcu_state = 1;
      fork
	 mcu_cson (address);
	 mcu_wron (address);
	 mcu_wdon (address);
	 mcu_cswwait (address);
      join
      mcu_state = 2;

      bclk0;
      bclk1;
      wr0 = 1;
      wr1 = 1;

      mcu_state = 3;
      fork
	 mcu_wdoff (address);
	 mcu_cswoff (address);
      join
      mcu_state = 4;
   end
endtask


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