status_registers.v

一个在FPGA芯片上实现UART功能的vhdl源代码

// renoir header_start
//
// Module UART_V.status_registers.interface
//
// Created:
//          by - user.group (host.domain)
//          at - 13:03:34 29/08/2001
//
// Generated by Mentor Graphics' HDL Designer(TM)
//
// renoir header_end

module status_registers( 
   clear_flags, 
   clk, 
   done_rcving, 
   done_xmitting, 
   rcving, 
   rst, 
   xmitting, 
   int, 
   status
);


// Internal Declarations

input        clear_flags;
input        clk;
input        done_rcving;
input        done_xmitting;
input        rcving;
input        rst;
input        xmitting;
output       int;
output [7:0] status;


wire clear_flags;
wire clk;
wire done_rcving;
wire done_xmitting;
wire rcving;
wire rst;
wire xmitting;
wire int;
wire [7:0] status;

// renoir interface_end

reg xmitting_reg, done_xmitting_reg, rcving_reg, done_rcving_reg;

always @(posedge clk or negedge rst)
   begin
      if( ~rst ) begin
         xmitting_reg=0;
         done_xmitting_reg=0;
         rcving_reg=0;
         done_rcving_reg=0;
      end
      else if( clear_flags ) begin
         xmitting_reg=0;
         done_xmitting_reg=0;
         rcving_reg=0;
         done_rcving_reg=0;
      end
      else begin
   	     xmitting_reg=xmitting;
         rcving_reg=rcving;
         if( done_xmitting==1 ) begin
            done_xmitting_reg=done_xmitting;
         end
         if( done_rcving==1 ) begin
            done_rcving_reg=done_rcving;
         end
      end
   end

   //Assert interrupt if transmitting or rcving complete
   assign int = (done_xmitting_reg || done_rcving_reg) ? 1 : 0;
   //Compose status registers
   assign status[7:4] = 4'b0000;
   assign status[3] = done_rcving_reg;
   assign status[2] = done_xmitting_reg;
   assign status[1] = rcving_reg;
   assign status[0] = xmitting_reg;

endmodule