`include "params.v"

/*-----------------------------------*/
// Module	: CONTROL  
// File		: control.v 
// Description	: Description of Control Unit in Viterbi Decoder 
// Simulator	: Modelsim 4.6 / Windows 98 
// Synthesizer	: -
// Author	: M Zalfany U (zalfany@opencores.org) 
/*-----------------------------------*/
// Revision Number 	: 1 
// Date of Change 	: 10th Jan 2000 
// Modifier 		: Zalfany 
// Description 		: Initial Design 
/*-----------------------------------*/

module CONTROL (Reset, CLOCK, Clock1, Clock2, ACSPage, ACSSegment, Active, 
		CompareStart, Hold, Init, TB_EN);


input Reset, CLOCK, Active;

output [`WD_FSM-1:0] ACSSegment;
output [`WD_DEPTH-1:0] ACSPage;
output Clock1, Clock2;
output Hold, Init, CompareStart;
output TB_EN;

reg [`WD_FSM-1:0] ACSSegment;
reg [`WD_DEPTH-1:0] ACSPage;

reg Init,Hold;

wire EVENT_1,EVENT_0;

reg TB_EN;

reg CompareStart;
reg [3:0] CompareCount;

reg count,Clock1, Clock2;

// Clock1 and Clock2 
   always @(posedge CLOCK or negedge Reset) 
      if (~Reset) count <= 0; else count <= ~count;
   
   always @(posedge CLOCK or negedge Reset) 
   begin 
      if (~Reset) 
        begin
           Clock1 <= 0; 
           Clock2 <= 0;
        end
      else
        begin
          if (count) Clock1 <=~Clock1;
          if (~count) Clock2 <= ~Clock2;
        end
   end
// ---
   
   assign EVENT_1 = (ACSSegment == 6'h3E);
   assign EVENT_0 = (ACSSegment == 6'h3F);
   
   always @(posedge Clock1 or negedge Reset)
   begin
     if (~Reset) 
        begin
           {ACSPage,ACSSegment} <= 'hFFFFF;
           Init <=0;
           Hold <= 0;
           TB_EN <= 0;
        end     
     else if (Active) 
          begin
             // Increase ACSSegment and Page
             {ACSPage,ACSSegment} <= {ACSPage,ACSSegment} + 1;

             // Init and Hold signal       
             if (EVENT_1) begin Init <= 0; Hold <= 1; end 
              else if (EVENT_0) begin Init <= 1; Hold <= 0; end 
                    else begin {Init,Hold} <= 0; end

             // enable TB after 63 sets of survivor created
             if ((ACSSegment == 'h3F) && (ACSPage == 'h3E)) TB_EN <= 1;
        end
   end

// For the first K-1, no COMPARISON made. Survivor is coming from '0' branch.
   always @(posedge Clock2 or negedge Reset) 
   begin 
     if (~Reset) 
          begin 
              CompareCount <= 0; 
              CompareStart <= 0;
          end
     else begin
          if (~CompareStart && EVENT_1) CompareCount <= CompareCount + 1;
          if (CompareCount == `CONSTRAINT-1 && EVENT_0) CompareStart <= 1;
          end
   end

endmodule