Subversion Repositories pairing

// f3_add: C == A+B (mod 3)
module f3_add(A, B, C);
    input [1:0] A, B;
    output [1:0] C;
    wire a0, a1, b0, b1, c0, c1;
    assign {a1, a0} = A;
    assign {b1, b0} = B;
    assign C = {c1, c0};
    assign c0 = ( a0 & !a1 & !b0 & !b1) |
                (!a0 & !a1 &  b0 & !b1) |
                (!a0 &  a1 & !b0 &  b1) ;
    assign c1 = (!a0 &  a1 & !b0 & !b1) |
                ( a0 & !a1 &  b0 & !b1) |
                (!a0 & !a1 & !b0 &  b1) ;
endmodule
 
// f3_sub: C == A-B (mod 3)
module f3_sub(A, B, C);
    input [1:0] A, B;
    output [1:0] C;
    f3_add m1(A, {B[0], B[1]}, C);
endmodule
 
// f3_mult: C = A*B (mod 3)
module f3_mult(A, B, C); 
	input [1:0] A;
	input [1:0] B; 
	output [1:0] C;
	wire a0, a1, b0, b1;
	assign {a1, a0} = A;
	assign {b1, b0} = B;
	assign C[0] = (!a1 & a0 & !b1 & b0) | (a1 & !a0 & b1 & !b0);
	assign C[1] = (!a1 & a0 & b1 & !b0) | (a1 & !a0 & !b1 & b0);
endmodule