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[/] [qaz_libs/] [trunk/] [basal/] [src/] [FIFOs/] [CummingsSNUG2002SJ_FIFO1/] [rptr_empty.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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  rptr_empty
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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                  rempty,
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    output      [ADDRSIZE-1:0]  raddr,
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    output reg  [ADDRSIZE :0]   rptr,
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    input       [ADDRSIZE :0]   rq2_wptr,
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    input                       rinc,
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    input                       rclk,
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    input                       rrst_n
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  );
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  reg [ADDRSIZE:0] rbin;
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  wire [ADDRSIZE:0] rgraynext, rbinnext;
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  //-------------------
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  // GRAYSTYLE2 pointer
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  //-------------------
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  always @(posedge rclk or negedge rrst_n)
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    if(!rrst_n)
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      {rbin, rptr} <= 0;
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    else
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      {rbin, rptr} <= {rbinnext, rgraynext};
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  // Memory read-address pointer (okay to use binary to address memory)
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  assign raddr = rbin[ADDRSIZE-1:0];
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  assign rbinnext = rbin + (rinc & ~rempty);
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  assign rgraynext = (rbinnext>>1) ^ rbinnext;
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  //---------------------------------------------------------------
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  // FIFO empty when the next rptr == synchronized wptr or on reset
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  //---------------------------------------------------------------
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  assign rempty_val = (rgraynext == rq2_wptr);
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  always @(posedge rclk or negedge rrst_n)
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    if(!rrst_n)
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      rempty <= 1'b1;
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    else
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      rempty <= rempty_val;
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endmodule
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