`include "macros.v"

// fifo *ship*: a 16-deep word-wide fifo
module fifo (clk, 
             in_r,  in_a, in_d,
             out_r, out_a, out_d);

  input  clk;
  input  in_r;
  input  out_a;
  output in_a;
  output out_r;
  input  [(`DATAWIDTH-1):0] in_d;
  output [(`DATAWIDTH-1):0] out_d;

  wire   [(`DATAWIDTH-1):0] d12;
  wire   [(`DATAWIDTH-1):0] d23;
  wire   [(`DATAWIDTH-1):0] d34;

  fifo4 s1(clk, in_r, in_a, in_d, r12, a12,     d12);
  fifo4 s2(clk, r12,  a12,  d12,  r23, a23,     d23);
  fifo4 s3(clk, r23,  a23,  d23,  r34, a34,     d34);
  fifo4 s4(clk, r34,  a34,  d34,  out_r, out_a, out_d);

endmodule