AHDL: Cycle-Shared FIFO (csfifo)

This example implements a cycle-shared FIFO with 256 8-bit words. The size of the FIFO is defined with the parameters LPM_WIDTH and LPM_WIDTHAD. This example uses an Include Statement (shown in blue text) to import the contents of the Include File containing the Function Prototype for the csfifo function. An Instance Declaration (shown in red text) implements an instance of the function.

If you are using this function in a FLEX 10K design, MAX+PLUS II will implement the FIFO in embedded array blocks (EABs).

For more information on using this example in your project, go to:

• How to Use AHDL Examples
• Graphic Editor: Cycle-Shared FIFO (csfifo)
• MAX+PLUS II Help

---

fifo.tdf

INCLUDE "csfifo.inc";
 
SUBDESIGN fifo
(
   dataf[7..0]       : INPUT;
   qf[7..0]          : OUTPUT;
      
   wreq              : INPUT;
   rreq              : INPUT;
     
   clk               : INPUT;
   clk2              : INPUT;
   clr               : INPUT;
     
   threshlevel[7..0] : INPUT;
   empty             : OUTPUT;
   full              : OUTPUT;
   threshold         : OUTPUT;
)
     
VARIABLE
  vxififo           : csfifo  
      WITH (LPM_WIDTH = 8, LPM_NUMWORDS = 256);
     
BEGIN
   -- Input definition for VXI FIFO
     
   vxififo.clock = clk;
   vxififo.clockx2 = clk2;
   vxififo.clr = clr;
     
   vxififo.data[7..0] = dataf[7..0];
     
   vxififo.threshlevel[7..0] = threshlevel[7..0];
   vxififo.wreq = wreq;
   vxififo.rreq = rreq;
   
   qf[7..0] = vxififo.q[7..0];
   
   threshold = vxififo.threshold;
   empty = vxififo.empty;
   full = vxififo.full;
      
END;

---

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