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44 lines
1 KiB
Systemverilog
44 lines
1 KiB
Systemverilog
// You are given an 8 litre bucket of water, and two empty buckets which can
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// contain 5 and 3 litre respectively. You are required to divide the water into
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// two by pouring water between buckets (that is, to end up with 4 litre in the 8
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// litre bucket, and 4 litre in the 5 litre bucket).
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//
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// Inspired by:
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// https://github.com/DennisYurichev/random_notes/blob/master/Z3/pour.py
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module pour_853_to_4 (
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input clk,
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input [1:0] src, dst
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);
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reg [3:0] state [0:2];
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reg [3:0] max_amount [0:2];
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reg [3:0] xfer_amount;
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initial begin
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state[0] = 8;
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state[1] = 0;
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state[2] = 0;
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max_amount[0] = 8;
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max_amount[1] = 5;
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max_amount[2] = 3;
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end
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always @* begin
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assume (src < 3);
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assume (dst < 3);
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assume (src != dst);
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if (state[src] > (max_amount[dst] - state[dst]))
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xfer_amount = max_amount[dst] - state[dst];
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else
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xfer_amount = state[src];
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cover (state[0] == 4 && state[1] == 4);
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end
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always @(posedge clk) begin
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state[src] <= state[src] - xfer_amount;
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state[dst] <= state[dst] + xfer_amount;
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end
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endmodule
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