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[/] [eco32/] [trunk/] [fpga/] [mc/] [src/] [ser/] [xmtbuf.v] - Blame information for rev 288

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Line No. Rev Author Line
1 117 hellwig 
//
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// xmtbuf.v -- serial line transmitter buffer
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//
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6 27 hellwig 
module xmtbuf(clk, reset, write, ready, data_in, serial_out);
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    input clk;
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    input reset;
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    input write;
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    output reg ready;
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    input [7:0] data_in;
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    output serial_out;
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  reg [1:0] state;
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  reg [7:0] data_hold;
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  reg load;
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  wire empty;
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  xmt xmt1(clk, reset, load, empty, data_hold, serial_out);
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  always @(posedge clk) begin
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    if (reset == 1) begin
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      state <= 2'b00;
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      ready <= 1;
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      load <= 0;
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    end else begin
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      case (state)
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        2'b00:
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          begin
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            if (write == 1) begin
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              state <= 2'b01;
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              data_hold <= data_in;
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              ready <= 0;
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              load <= 1;
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            end
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          end
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        2'b01:
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          begin
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            state <= 2'b10;
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            ready <= 1;
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            load <= 0;
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          end
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        2'b10:
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          begin
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            if (empty == 1 && write == 0) begin
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              state <= 2'b00;
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              ready <= 1;
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              load <= 0;
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            end else
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            if (empty == 1 && write == 1) begin
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              state <= 2'b01;
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              data_hold <= data_in;
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              ready <= 0;
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              load <= 1;
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            end else
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            if (empty == 0 && write == 1) begin
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              state <= 2'b11;
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              data_hold <= data_in;
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              ready <= 0;
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              load <= 0;
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            end
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          end
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        2'b11:
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          begin
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            if (empty == 1) begin
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              state <= 2'b01;
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              ready <= 0;
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              load <= 1;
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            end
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          end
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      endcase
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    end
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  end
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endmodule

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