Subversion Repositories qaz_libs

// --------------------------------------------------------------------

//

// --------------------------------------------------------------------

`timescale 1ps/1ps

module

  recover_clock

  #(

    parameter PROFILE_COUNT   = 20

  )

  (

    input       in,

    output reg  clock

  );

  time  in_time_buffer;

  time  clock_period_buffer;

  time  clock_out_period = 1000000;

  integer count = 0;

  // --------------------------------------------------------------------

  //

  reg internal_clock;

  initial

    begin

      internal_clock <= 1'bx;

      wait( in === 0 );

      repeat( PROFILE_COUNT )

        begin

          @( posedge in );

          in_time_buffer  = $time;

          @( negedge in );

          clock_period_buffer = $time - in_time_buffer;

          if( clock_period_buffer < clock_out_period )

            clock_out_period = clock_period_buffer;

          count = count + 1;

        end

      $display( "-#- %16.t | recover_clock: period (in sim time) = %t", $time, clock_out_period );

      @( posedge in )

        internal_clock <= 1'b1;

      forever

        #(clock_out_period/2) internal_clock <= ~internal_clock;

    end

  // --------------------------------------------------------------------

  //

  time  delta = 0;

  time  delta_buffer = 0;

  always @( posedge internal_clock)

    delta_buffer <= $time;

  always @( posedge in)

    if( internal_clock !== 1'bx )

      delta <= ($time - delta_buffer) %  clock_period_buffer;

  // --------------------------------------------------------------------

  //

  always @( * )

    clock = #(delta) internal_clock;

endmodule