<div class="blockcode"><blockquote>/****************四选一逻辑**********************************/
/****************ID:共同学习stm8**********************************/
/**************************************************/
/*************20240329*************************************/
/*
当sel为00时y<=a&b;
当sel为01时y<=a|b;
当sel为10时y<=a^b;
当sel为11时y<=~(a^b);
*/
`timescale 1ns/10ps
module fn_sw_4(a, b, sel, y);
input a;
input b;
input[1:0] sel;
output y;
reg y;
always@(a or b or sel)
begin
case(sel)
2'b00:begin y<=a&b; end
2'b01:begin y<=a|b; end
2'b10:begin y<=a^b; end
//2'b11:begin y<=~(a^b); end
2'b11:begin y<=a~^b; end //同或
endcase
end
endmodule
/**************testbench of fn_sw_4************************************/
module fn_sw_4_tb;
reg[3:0] absel;
wire y;
fn_sw_4 fn_sw_4
(
.a(absel[0]),
.b(absel[1]),
.sel(absel[3:2]),
.y(y)
);
initial
begin
absel <=0;
#200 $stop;
end
always #10 absel<=absel+1;
endmodule
/**************************************************/
/**************************************************/
/**************************************************/
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