28 lines
650 B
Coq
28 lines
650 B
Coq
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`define WIDTH 8
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module linear_feedback_shift_register_updown (clk, reset, enable, up_down, count, overflow);
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input clk;
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input reset;
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input enable;
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input up_down;
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output [`WIDTH-1 : 0] count;
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output overflow;
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reg [`WIDTH-1 : 0] count;
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assign overflow = (up_down) ? (count == {{`WIDTH-1{1'b0}}, 1'b1}) :
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(count == {1'b1, {`WIDTH-1{1'b0}}}) ;
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always @(posedge clk)
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if (reset)
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count <= {`WIDTH{1'b0}};
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else if (enable) begin
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if (up_down) begin
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count <= {~(^(count & `WIDTH'b01100011)),count[`WIDTH-1:1]};
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end else begin
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count <= {count[`WIDTH-2:0],~(^(count & `WIDTH'b10110001))};
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end
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end
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endmodule
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