module fifo_2clock_cascade #(parameter WIDTH=32, SIZE=9) (input wclk, input [WIDTH-1:0] datain, input src_rdy_i, output dst_rdy_o, output [15:0] space, input rclk, output [WIDTH-1:0] dataout, output src_rdy_o, input dst_rdy_i, output [15:0] occupied, input arst); wire [WIDTH-1:0] data_int1, data_int2; wire src_rdy_int1, src_rdy_int2, dst_rdy_int1, dst_rdy_int2; wire [SIZE-1:0] level_wclk, level_rclk; wire [4:0] s1_space, s1_occupied, s2_space, s2_occupied; wire [15:0] l_space, l_occupied; fifo_short #(.WIDTH(WIDTH)) shortfifo (.clk(wclk), .reset(arst), .clear(0), .datain(datain), .src_rdy_i(src_rdy_i), .dst_rdy_o(dst_rdy_o), .dataout(data_int1), .src_rdy_o(src_rdy_int1), .dst_rdy_i(dst_rdy_int1), .space(s1_space), .occupied(s1_occupied) ); fifo_2clock #(.WIDTH(WIDTH),.SIZE(SIZE)) fifo_2clock (.wclk(wclk), .datain(data_int1), .src_rdy_i(src_rdy_int1), .dst_rdy_o(dst_rdy_int1), .space(l_space), .rclk(rclk), .dataout(data_int2), .src_rdy_o(src_rdy_int2), .dst_rdy_i(dst_rdy_int2), .occupied(l_occupied), .arst(arst) ); fifo_short #(.WIDTH(WIDTH)) shortfifo2 (.clk(rclk), .reset(arst), .clear(0), .datain(data_int2), .src_rdy_i(src_rdy_int2), .dst_rdy_o(dst_rdy_int2), .dataout(dataout), .src_rdy_o(src_rdy_o), .dst_rdy_i(dst_rdy_i), .space(s2_space), .occupied(s2_occupied)); // Be conservative -- Only advertise space from input side of fifo, occupied from output side assign space = {11'b0,s1_space} + l_space; assign occupied = {11'b0,s2_occupied} + l_occupied; endmodule // fifo_2clock_cascade