rptr_empty.v

module rptr_empty #(parameter ADDRSIZE = 4)
(output reg rempty,
output [ADDRSIZE-1:0] raddr,
output reg [ADDRSIZE :0] rptr,
input [ADDRSIZE :0] rq2_wptr,
input rinc, rclk, rrst_n);
reg [ADDRSIZE:0] rbin;
wire [ADDRSIZE:0] rgraynext, rbinnext;
//-------------------
// GRAYSTYLE2 pointer
//-------------------
always @(posedge rclk or negedge rrst_n) begin
if (!rrst_n) {rbin, rptr} <=  10'b0000000000;
else {rbin, rptr} <= {rbinnext, rgraynext}; end
// Memory read-address pointer (okay to use binary to address memory)
assign raddr = rbin[ADDRSIZE-1:0];
assign rbinnext = rbin + (rinc & ~rempty);
assign rgraynext = (rbinnext>>1) ^ rbinnext;
//---------------------------------------------------------------
// FIFO empty when the next rptr == synchronized wptr or on reset
//---------------------------------------------------------------
assign rempty_val = (rgraynext == rq2_wptr);
always @(posedge rclk or negedge rrst_n) begin
if (!rrst_n) rempty <= 1'b1;
else rempty <= rempty_val; end
endmodule