alu.v

debussy中文使用手册

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/* Debussy tutorial case: A simplified microprogramming-based CPU
   file name: alu.v
   description: this parts perform the arithmetic and login funtion 
 	        which is defined by mode select

		a,b: operand data inputs
		cin: carry input
		select: alu function select
		dout: alu result data output
		carry: alu result carry output
		zero: alu result zero output
*/

`timescale 1 ns / 1 ns

module alu(a, b, cin, select, out, carry, zero);
input [7:0] a;
input [7:0] b;
input cin;
input [2:0] select;
output [7:0] out;
output carry;
output zero;
 assign #1 {carry,out}= (select==0) ? a + b + cin 
	: (select==1) ? a - b - 1 + cin 
	: (select==2) ? b - a - 1 + cin
	: (select==3) ? a & b
	: (select==4) ? a | b
	: (select==5) ? a ^ b
	: (select==6) ? a ^~ b
	: 0;
 assign zero = (out==0) ? 1 : 0;
endmodule