// sim/fp_mult_tb.sv
`timescale 1ns/1ps

module fp_mult_tb;

    logic [31:0] a, b, z;
    logic [2:0] rnd;
    logic [7:0] status;
    logic clk = 0, rst = 0;

    // DUT
    fp_mult dut (
        .a(a),
        .b(b),
        .rnd(rnd),
        .z(z),
        .status(status),
        .clk(clk),
        .rst(rst)
    );

    // Clock generation
    always #5 clk = ~clk;

    typedef struct {
        logic [31:0] a;
        logic [31:0] b;
        logic [31:0] expected;
        string       desc;
    } test_vector_t;

    test_vector_t tests [11];

    initial begin
        $display("Starting fp_mult test...\n");

        // Normal multiplication cases
        tests[0] = '{32'h3f800000, 32'h40000000, 32'h40400000, "1.0 * 2.0 = 2.0"};
        tests[1] = '{32'h40400000, 32'h40400000, 32'h40c00000, "3.0 * 3.0 = 9.0"};
        tests[2] = '{32'hbf800000, 32'h40000000, 32'hc0400000, "-1.0 * 2.0 = -2.0"};
        tests[3] = '{32'h3f000000, 32'h3f000000, 32'h3e800000, "0.5 * 0.5 = 0.25"};
        tests[4] = '{32'h3f800000, 32'h00000000, 32'h00000000, "1.0 * 0.0 = 0.0"};

        // Corner cases (some may fail if not handled yet)
        tests[5] = '{32'h7f800000, 32'h3f800000, 32'h7f800000, "inf * 1.0 = inf"};
        tests[6] = '{32'hff800000, 32'h3f800000, 32'hff800000, "-inf * 1.0 = -inf"};
        tests[7] = '{32'h7fc00000, 32'h3f800000, 32'h7fc00000, "NaN * 1.0 = NaN"};
        tests[8] = '{32'h00800000, 32'h00800000, 32'h00000000, "denorm * denorm = underflow"};
        tests[9] = '{32'h7f7fffff, 32'h7f7fffff, 32'h7f800000, "max * max = inf (overflow)"};
        tests[10] = '{32'h00000000, 32'hff800000, 32'hffc00000, "0.0 * -inf = NaN"};

        rnd = 3'b000; // default round to nearest
        rst = 1; #10;
        rst = 0; #10;

        for (int i = 0; i < 11; i++) begin
            a = tests[i].a;
            b = tests[i].b;
            #20;
            $display("[%0d] %s", i+1, tests[i].desc);
            $display("     A=%h B=%h => Z=%h (expected %h) %s\n",
                     a, b, z, tests[i].expected,
                     (z === tests[i].expected) ? "PASS" : "FAIL");
        end

        $display("\nFinished fp_mult test.");
        $stop;
    end

endmodule