Subversion Repositories qaz_libs

// --------------------------------------------------------------------
//
 
 
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,
    input                       rclk,
    input                       rrst_n
  );
 
  reg [ADDRSIZE:0] rbin;
  wire [ADDRSIZE:0] rgraynext, rbinnext;
 
  //-------------------
  // GRAYSTYLE2 pointer
  //-------------------
  always @(posedge rclk or negedge rrst_n)
    if(!rrst_n)
      {rbin, rptr} <= 0;
    else
      {rbin, rptr} <= {rbinnext, rgraynext};
 
  // 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)
    if(!rrst_n)
      rempty <= 1'b1;
    else
      rempty <= rempty_val;
 
endmodule