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[/] [qaz_libs/] [trunk/] [BFM/] [src/] [clock/] [recover_clock.v] - Blame information for rev 34

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1 34 qaztronic
// --------------------------------------------------------------------
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//
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// --------------------------------------------------------------------
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`timescale 1ps/1ps
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module
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  recover_clock
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  #(
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    parameter PROFILE_COUNT   = 20
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  )
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  (
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    input       in,
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    output reg  clock
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  );
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  time  in_time_buffer;
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  time  clock_period_buffer;
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  time  clock_out_period = 1000000;
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  integer count = 0;
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  // --------------------------------------------------------------------
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  //
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  reg internal_clock;
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  initial
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    begin
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      internal_clock <= 1'bx;
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      wait( in === 0 );
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      repeat( PROFILE_COUNT )
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        begin
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          @( posedge in );
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          in_time_buffer  = $time;
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          @( negedge in );
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          clock_period_buffer = $time - in_time_buffer;
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          if( clock_period_buffer < clock_out_period )
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            clock_out_period = clock_period_buffer;
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          count = count + 1;
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        end
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      $display( "-#- %16.t | recover_clock: period (in sim time) = %t", $time, clock_out_period );
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      @( posedge in )
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        internal_clock <= 1'b1;
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      forever
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        #(clock_out_period/2) internal_clock <= ~internal_clock;
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    end
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  // --------------------------------------------------------------------
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  //
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  time  delta = 0;
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  time  delta_buffer = 0;
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  always @( posedge internal_clock)
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    delta_buffer <= $time;
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  always @( posedge in)
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    if( internal_clock !== 1'bx )
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      delta <= ($time - delta_buffer) %  clock_period_buffer;
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  // --------------------------------------------------------------------
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  //
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  always @( * )
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    clock = #(delta) internal_clock;
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endmodule
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