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[/] [qaz_libs/] [trunk/] [basal/] [src/] [FIFOs/] [CummingsSNUG2002SJ_FIFO1/] [wptr_full.v] - Blame information for rev 34

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1 34 qaztronic
// --------------------------------------------------------------------
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//
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module
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  wptr_full
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  #(
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    parameter ADDRSIZE = 4
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  )
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  (
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    output reg                  wfull,
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    output      [ADDRSIZE-1:0]  waddr,
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    output reg  [ADDRSIZE :0]   wptr,
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    input       [ADDRSIZE :0]   wq2_rptr,
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    input                       winc,
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    input                       wclk,
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    input                       wrst_n
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  );
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  reg [ADDRSIZE:0] wbin;
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  wire [ADDRSIZE:0] wgraynext, wbinnext;
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  // GRAYSTYLE2 pointer
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  always @(posedge wclk or negedge wrst_n)
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    if(!wrst_n)
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      {wbin, wptr} <= 0;
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    else
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      {wbin, wptr} <= {wbinnext, wgraynext};
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  // Memory write-address pointer (okay to use binary to address memory)
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  assign waddr = wbin[ADDRSIZE-1:0];
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  assign wbinnext = wbin + (winc & ~wfull);
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  assign wgraynext = (wbinnext>>1) ^ wbinnext;
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  //------------------------------------------------------------------
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  // Simplified version of the three necessary full-tests:
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  // assign wfull_val=((wgnext[ADDRSIZE] !=wq2_rptr[ADDRSIZE] ) &&
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  // (wgnext[ADDRSIZE-1] !=wq2_rptr[ADDRSIZE-1]) &&
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  // (wgnext[ADDRSIZE-2:0]==wq2_rptr[ADDRSIZE-2:0]));
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  //------------------------------------------------------------------
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  assign wfull_val = (wgraynext == {~wq2_rptr[ADDRSIZE:ADDRSIZE-1], wq2_rptr[ADDRSIZE-2:0]});
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  always @(posedge wclk or negedge wrst_n)
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    if(!wrst_n)
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      wfull <= 1'b0;
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    else
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      wfull <= wfull_val;
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endmodule
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