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arbiter.v
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arbiter.v
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module round_robin_4
(
input wire clock,
input wire reset,
input wire [3:0] request,
output wire [3:0] grant
);
reg [$clog2(4)-1:0] counter;
wire [3:0] priority [3:0];
assign grant[0-:1] = priority[0][0-:1] | priority[1][3-:1] | priority[2][2-:1] | priority[3][1-:1] ;
assign grant[1-:1] = priority[0][1-:1] | priority[1][0-:1] | priority[2][3-:1] | priority[3][2-:1] ;
assign grant[2-:1] = priority[0][2-:1] | priority[1][1-:1] | priority[2][0-:1] | priority[3][3-:1] ;
assign grant[3-:1] = priority[0][3-:1] | priority[1][2-:1] | priority[2][1-:1] | priority[3][0-:1] ;
// Ring Counter
always @(posedge clock)
if (reset)
counter <= 0;
else
counter <= counter + 1;
priority_encoder
#(
.NO_INPUTS(4)
) U_priority_encoder_0 (
.enable((counter == 0)),
.in({request[0],request[1],request[2],request[3]}),
.out(priority[0])
);
priority_encoder
#(
.NO_INPUTS(4)
) U_priority_encoder_1 (
.enable((counter == 1)),
.in({request[1],request[2],request[3],request[0]}),
.out(priority[1])
);
priority_encoder
#(
.NO_INPUTS(4)
) U_priority_encoder_2 (
.enable((counter == 2)),
.in({request[2],request[3],request[0],request[1]}),
.out(priority[2])
);
priority_encoder
#(
.NO_INPUTS(4)
) U_priority_encoder_3 (
.enable((counter == 3)),
.in({request[3],request[0],request[1],request[2]}),
.out(priority[2])
);
endmodule