/* simple_core */
// Author Andrew Laffely
// Last modified: 12 Feb 03

module adder_core (reset, hold, in_ready, out_ready, data_in, data_out, read, write, in_addr, out_addr);
input reset, hold;                // External control signals
input [2:0] in_ready, out_ready;  // Input and Output port ready registers
input [31:0] data_in;             // Input data

output read, write;               // Read and Write signals
output [31:0] data_out;
output [1:0] in_addr, out_addr;   // Port addresses.
reg read, write; 
reg [31:0] data_out;
reg [1:0] in_addr, out_addr;   

reg [31:0] opA, opB;
reg [31:0] res;
reg ops_ready, res_ready; //Internal flow conrol
reg stall, go;
  
reg lclock;
initial
begin
	#3 lclock = 1'b0;
	forever #47 lclock = ~lclock;  // Use 10 or 20 or 40 or 80 etc.
end

/*********************** READ DATA *****************************/
always @ (posedge lclock)
  begin
	#1 if(((!ops_ready)||(!stall))&&(!hold)&&(!reset))  
	// Do not read anymore if full and stalled
		if(in_ready[in_addr])  // check port
			read = 1;
  end

always @ (negedge lclock)
  begin
	read = 0;
  end

always @ (negedge read)
  begin
    if (!reset)
      begin
	if ((in_addr[0])&&(!hold))
	  begin
		opB=data_in;
		ops_ready=1;
	  end
	else
	  begin
		opA=data_in;
	  end
	$display("In Core=%h addr=%b ops_ready=%b",data_in, in_addr, ops_ready);
	#1 in_addr[0]=~in_addr[0];   // next data	
      end
  end
/********************* End READ DATA ***************************/

/*********************** Write DATA ****************************/
always @ (posedge lclock)
  begin
	if((res_ready)&&(!hold)&&(!reset)) // wait until the pipe is full
		if(out_ready[out_addr])  // check port
			write = 1;
  end

always @ (negedge lclock)
  begin
	write = 0;
  end

always @ (negedge write)
  begin
	if(!reset)
	  begin
		data_out=res;
		$display("Out Core=%h out_addr=%b ops_ready=%b",data_out, out_addr, ops_ready);
	res_ready=0;
	  end
  end
/******************** End Write DATA ***************************/

/************************ Reset ********************************/
always @ (reset)
  begin
	read=0;
	write=0;
	in_addr=0;
	out_addr=0;
	ops_ready=0;
	res_ready=0;
	stall = 0;
  end
/*********************** End Reset *****************************/

/******************* Core flow Control *************************/
// stall tells the pipeline to stop adding and stop taking in data
always @ (posedge lclock)
  begin
	if(!out_ready[out_addr])
		stall = 1;
  end

always @ (posedge out_ready[out_addr])
  begin
	stall=0;
  end
/******************* End flow Control *************************/

/************************ Proccessing *************************/
always @ (posedge lclock)
  begin
	if((ops_ready)&&(!stall)&&(!hold))
	  begin
		res=opA+opB;  //Wow this 32 bit adder is fast
		res_ready=1;
		ops_ready=0;
		
	  end
  end
/********************* End Proccessing *************************/
endmodule