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

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// OpenSPARC T2 Processor File: niu_zcp_ififo_sm.v
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/*%W%   %G%*/

/***************************************************************
 *
 * File Name    : niu_zcp_ififo_sm.v
 * Author Name  : John Lo
 * Description  : niu_zcp_fflp_intf control path
 * Parent Module:
 * Child  Module:
 * Interface Mod:
 * Date Created : 3/18/05
 *
 * Copyright (c) 2020, Sun Microsystems, Inc.
 * Sun Proprietary and Confidential
 *
 * Modification :
 *
 * Synthesis Notes:
 *
 * Design Notes: When adding more CAL states DON'T forget to
 *               modify tt_atomic_op.
 *
 *
 **************************************************************/


module niu_zcp_ififo_sm
  (/*AUTOARG*/
   // Outputs
   ififo_ren1, ififo_ren, ififo_state,
   // Inputs
   clk, reset, empty
   );


   input                      clk;
   input                      reset;
   input                      empty;
                              // outputs
   output                     ififo_ren1;
   output [2:0]               ififo_ren;
   output [2:0]               ififo_state;

   wire   [2:0]               ififo_state;
   reg    [2:0]               nx_ififo_state;
   reg                        kickoff_rd;
   parameter   ZERO              = 3'h0,
               ONE               = 3'h1,
               TWO               = 3'h2,
               THREE             = 3'h3,
               FOUR              = 3'h4,
               FIVE              = 3'h5,
               SIX               = 3'h6,
               SEVEN             = 3'h7;

// comb part
always @ (/*AUTOSENSE*/empty or ififo_state)
 begin
                  nx_ififo_state      = ZERO;
                  kickoff_rd        = 0;
   casex (ififo_state)  // synopsys parallel_case
     ZERO: if (~empty)
             begin
                  nx_ififo_state      = ONE;
                  kickoff_rd          = 1;
             end // if (~empty)
           else   nx_ififo_state      = ififo_state; // stay
     ONE:         nx_ififo_state      = TWO;
     TWO:         nx_ififo_state      = THREE;
     THREE:       nx_ififo_state      = FOUR;
     FOUR:        nx_ififo_state      = FIVE;
     FIVE:        nx_ififo_state      = SIX;
     SIX:         nx_ififo_state      = SEVEN;
     SEVEN:       nx_ififo_state      = ZERO;
     default:begin
                  nx_ififo_state      = ZERO;
                  kickoff_rd          = 0;
                  // synopsys translate_off
                  $display("(* ERROR: at sim time = %d, niu_zcp_ififo_sm is in forbidden state *) \n", $time);
                  // synopsys translate_on
             end
   endcase // casex(ififo_state)
 end // always @ (...


// seq part
zcp_RegRst #(3) ififo_state_RegRst(.din(nx_ififo_state[2:0]),.clk(clk),.reset(reset),.qout(ififo_state[2:0]));

// glue logic
zcp_RegRst #(4) ififo_ren_RegRst(.din({4{kickoff_rd}}),.clk(clk),.reset(reset),.qout({ififo_ren1,ififo_ren[2:0]}));


endmodule // niu_zcp_ififo_sm