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[/] [qaz_libs/] [trunk/] [basal/] [src/] [FIFOs/] [CummingsSNUG2002SJ_FIFO1/] [wptr_full.v] - Rev 34

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// --------------------------------------------------------------------
//
 
 
module 
  wptr_full 
  #(
    parameter ADDRSIZE = 4
  )
  (
    output reg                  wfull,
    output      [ADDRSIZE-1:0]  waddr,
    output reg  [ADDRSIZE :0]   wptr,
    input       [ADDRSIZE :0]   wq2_rptr,
    input                       winc,
    input                       wclk,
    input                       wrst_n
  );
 
  reg [ADDRSIZE:0] wbin;
  wire [ADDRSIZE:0] wgraynext, wbinnext;
 
  // GRAYSTYLE2 pointer
  always @(posedge wclk or negedge wrst_n)
    if(!wrst_n) 
      {wbin, wptr} <= 0;
    else 
      {wbin, wptr} <= {wbinnext, wgraynext};
 
  // Memory write-address pointer (okay to use binary to address memory)
  assign waddr = wbin[ADDRSIZE-1:0];
  assign wbinnext = wbin + (winc & ~wfull);
  assign wgraynext = (wbinnext>>1) ^ wbinnext;
 
  //------------------------------------------------------------------
  // Simplified version of the three necessary full-tests:
  // assign wfull_val=((wgnext[ADDRSIZE] !=wq2_rptr[ADDRSIZE] ) &&
  // (wgnext[ADDRSIZE-1] !=wq2_rptr[ADDRSIZE-1]) &&
  // (wgnext[ADDRSIZE-2:0]==wq2_rptr[ADDRSIZE-2:0]));
  //------------------------------------------------------------------
  assign wfull_val = (wgraynext == {~wq2_rptr[ADDRSIZE:ADDRSIZE-1], wq2_rptr[ADDRSIZE-2:0]});
 
  always @(posedge wclk or negedge wrst_n)
    if(!wrst_n) 
      wfull <= 1'b0;
    else 
      wfull <= wfull_val;
 
endmodule
 
 

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