`include "asu.sv"

module asu_tb #(width=8)();
    logic [0:0] op;
    logic [width-1:0] A;
    logic [width-1:0] B;
    logic [width-1:0] C;
    logic [0:0] Cout;
    logic [0:0] Cin;
    logic [width-1:0] C_exp;
    logic [0:0] Cout_exp;
    logic [0:0] Cin_exp;   // TODO
    
    logic [0:0] Signed_overflow;

    asu #(width) dut(op, A, B, C, Cout, Cin);

    integer error_count;
    initial begin
        error_count = 0;
        $display("Beginning ASU tests");

        // Test basic addition of 0+1 = 1
        op = 1'b0;
        A = {width{1'b0}};
        B = { {(width-1){1'b0}}, 1'b1};
        C_exp = { {(width-1){1'b0}}, 1'b1};
        Cout_exp = 1'b0;
        Cin_exp = 1'b0;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        // Test underflow from 0-1 = UINTMAX
        op = 1'b1;
        C_exp = {(width){1'b1}};
        Cout_exp = 1'b0;
        Cin_exp = 1'b0;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        // Test carry addition of 1+1 = 2
        op = 1'b0;
        A = { {(width-1){1'b0}}, 1'b1};
        B = { {(width-1){1'b0}}, 1'b1};
        C_exp = { {(width-2){1'b0}}, 2'b10};
        Cout_exp = 1'b0;
        Cin_exp = 1'b0;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        // Test overflow from  UINTMAX+1 = 0
        A = {(width){1'b1}};            // UINTMAX
        B = { {(width-1){1'b0}}, 1'b1}; // 1
        C_exp = {(width){1'b0}};
        Cout_exp = 1'b1;
        Cin_exp = 1'b1;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        // Tests INTMAX+1
        op = 1'b0;
        A = {1'b0, {(width-1){1'b1}}};          // INTMAX
        B = {{(width-1){1'b0}}, 1'b1};          // 1
        C_exp    = {1'b1, {(width-1){1'b0}}};   // -INTMAX
        Cin_exp  = 1'b1;
        Cout_exp = 1'b0;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        op = 1'b0;
        A = {1'b1, {(width-1){1'b0}}};  // -INTMAX
        B = {1'b1, {(width-1){1'b0}}};  // -INTMAX
        C_exp    = {width{1'b0}};       // 0
        Cin_exp  = 1'b0;
        Cout_exp = 1'b1;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        op = 1'b1;
        A = {1'b0, {(width-1){1'b1}}}; // INTMAX
        B = {1'b1, {(width-1){1'b0}}}; // -INTMAX
        C_exp    = {width{1'b1}};      // -1
        Cin_exp  = 1'b1;
        Cout_exp = 1'b0;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        op = 1'b1;
        A = {1'b1, {(width-1){1'b0}}};          // -INTMAX
        B = {{(width-1){1'b0}}, 1'b1};          // 1
        C_exp    = {1'b0, {(width-1){1'b1}}};   // INTMAX
        Cin_exp  = 1'b0;
        Cout_exp = 1'b1;
        #1;
        if (C != C_exp || Cout != Cout_exp || Cin != Cin_exp || (Cin ^ Cout) != (Cin_exp ^ Cout_exp)) begin
            $display("\t\x1b[38;5;9mOp 0b%b(0b%b, 0b%b) produced 0b%b%b_%b but 0b%b%b_%b was expected\x1b[m", op, A, B, Cin, Cout, C, Cin_exp, Cout_exp, C_exp);
            error_count = error_count + 1;
        end

        if (error_count == 0) $display("\x1b[38;5;10mAll ASU tests passing\x1b[m");
        else $display("\x1b[38;5;9m%0d ASU test(s) failing\x1b[m", error_count);
    end
endmodule