【HDLBits刷题】Kmap4.

Implement the circuit described by the Karnaugh map below.

Try to simplify the k-map before coding it. Try both product-of-sums and sum-of-products forms. We can't check whether you have the optimal simplification of the k-map. But we can check if your reduction is equivalent, and we can check whether you can translate a k-map into a circuit.

这题没法通过卡诺图化简，写了8个最小项，通过公式法化简。

a’bc’d’+ab’c’d’+a’b’c’d+abc’d+a’bcd+ab’cd+a’b’cd’+abcd’

=（a’bc’d’+ab’c’d’）+（a’b’c’d+abc’d）+（a’bcd+ab’cd）+（a’b’cd’+abcd’）

=(a^b)c’d’ + (a~^b)c’d + (a^b)cd + (a~^b)cd’

=(a^b)&(c~^d) | (a~^b)&(c^d)  // A ~B   ~A  B

=(a^b)^(c^d)

module top_module(
    input a,
    input b,
    input c,
    input d,
    output out  ); 
    assign out = (a^b)^(c^d);
endmodule