if

// Simple 4-1 mux

module mux4 (sel, A, B, C, D, Y);

input [1:0] sel; // 2-bit control signal

input A, B, C, D;

output Y;

reg Y; // target of assignment

always @(sel or A or B or C or D)

if (sel == 2’b00) Y = A;

else if (sel == 2’b01) Y = B;

else if (sel == 2’b10) Y = C;

else if (sel == 2’b11) Y = D;

endmodule

• Same as C if statement

  • Single if statements synthesize to multiplexers
  • Nested if /else statements usually synthesize to logic

Previous slide

Next slide

Back to first slide

View graphic version