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sby/docs/examples/puzzles/djb2hash.sv
Claire Wolf 3ec2b6b4e4 Add djb2hash example
Signed-off-by: Claire Wolf <claire@symbioticeda.com>
2020-04-09 19:46:19 +02:00

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Systemverilog

// find a hash collision for DJB2 hash where it visits the same state twice
module djb2hash (input clock);
(* keep *) rand const reg [31:0] magic;
(* keep *) rand reg [7:0] inputval;
(* keep *) reg [31:0] state = 5381;
(* keep *) integer cnt = 0;
always @(posedge clock) begin
state <= ((state << 5) + state) ^ inputval;
if (state == magic) cnt <= cnt + 1;
assert (cnt < 2);
end
endmodule