Witch of Git - nan-gate/blob - example/mult.sv

   1 module mult #(
   2     parameter WIDTH=32,
   3     parameter STAGES=4
   4 ) (
   5     input clock,
   6     input enable,
   7     input [WIDTH-1:0] A,
   8     input [WIDTH-1:0] B,
   9     output valid,
  10     output [WIDTH-1:0] O
  11 );
  12
  13 // Retiming really is magical...
  14 wire [WIDTH-1:0] prod = A * B;
  15 shift_reg #(.WIDTH(1), .DEPTH(STAGES)) shr_valid (.clock(clock), .in(enable), .out(valid));
  16 shift_reg #(.WIDTH(WIDTH), .DEPTH(STAGES)) shr_mul (.clock(clock), .in(prod), .out(O));
  17
  18 endmodule
  19
  20 module shift_reg #(
  21     parameter WIDTH=1,
  22     parameter DEPTH=4
  23 ) (
  24     input clock,
  25     input [WIDTH-1:0] in,
  26     output [WIDTH-1:0] out
  27 );
  28
  29 reg [WIDTH-1:0] state [DEPTH-1:0];
  30 assign out = state[DEPTH-1];
  31
  32 integer i;
  33 always @(posedge clock) begin
  34     state[0] <= in;
  35     for (i = 1; i < DEPTH; i=i+1) begin
  36         state[i] <= state[i-1];
  37     end
  38 end
  39
  40 endmodule
  41