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`default_nettype none
module lfsr_updown (
clk , // Clock input
reset , // Reset input
enable , // Enable input
up_down , // Up Down input
count , // Count output
overflow // Overflow output
);
input clk;
input reset;
input enable;
input up_down;
output [7 : 0] count;
output overflow;
reg [7 : 0] count;
assign overflow = (up_down) ? (count == {{7{1'b0}}, 1'b1}) :
(count == {1'b1, {7{1'b0}}}) ;
always @(posedge clk)
if (reset)
count <= {7{1'b0}};
else if (enable) begin
if (up_down) begin
count <= {~(^(count & 8'b01100011)),count[7:1]};
end else begin
count <= {count[5:0],~(^(count & 8'b10110001))};
end
end
endmodule
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