design/sys/iop/niu/rtl/tx_byte_counter.v

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/*******************************************************************
 *
 * File Name    : tx_byte_counter.v
 * Author Name  : John Lo
 * Description  :
 * Parent Module: xmac
 * Child  Module:
 * Interface Mod:
 * Date Created : 3/24/04
 *
 * Copyright (c) 2020, Sun Microsystems, Inc.
 * Sun Proprietary and Confidential
 *
 *
 * Modification :
 *
 * Synthesis Notes:
 *
 ******************************************************************/

module tx_byte_counter (
       tx_clk,
       tx_reset,
       last_byte_position,
       eop_tag,
       tx_byte_count_en,
// outputs
       tx_byte_count,
       nx_tx_byte_count
       );

   input           tx_clk;
   input           tx_reset;
   input [2:0]     last_byte_position;
   input           eop_tag;
   input           tx_byte_count_en;
   output [13:0]   tx_byte_count;
   output [13:0]   nx_tx_byte_count;

   reg [13:0]   nx_tx_byte_count;

always @ (tx_byte_count_en or eop_tag or tx_byte_count or last_byte_position)
  if (tx_byte_count_en)
    casex (eop_tag) // synopsys parallel_case full_case
       1'b0:    nx_tx_byte_count = tx_byte_count + 8; // in the middle of xfr
       1'b1:    nx_tx_byte_count = tx_byte_count + 1 + {11'b0,last_byte_position};
    endcase // casex({eop_tag})
  else          nx_tx_byte_count = tx_byte_count ;


 // We can only support 16k jumbo packet
RegRst #(14) tx_byte_count_RegRst (
.clk(tx_clk),
.reset(tx_reset),
.din(nx_tx_byte_count),
.qout(tx_byte_count));

endmodule // tx_byte_counter