//////////////////////////////////////////////////////////////////////////////// /// /// Template for LSU EE 3755 Spring 2002 Homework 1 /// /// Instructions: // // Copy this to a file named hw01.v to directory ~/hw in your // class account. (~ is your home directory.) Use this // file for your solution. Your entire solution should be in // this file. // // Do not rename the modules in this file and be sure to use the // directory and filename given above. // Assignment: http://www.ee.lsu.edu/ee3755/2002/hw01.pdf //////////////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////////////// /// Problem 0 /// module hello(); initial begin \$display("Hello, world!"); end endmodule //////////////////////////////////////////////////////////////////////////////// /// Problem 1 /// // Complete the 2-to-4 decoder. See assignment for ports. // Explicit Structural: Use gates only on assign or operators. // Test using test_decoder. module decode_2_to_4(); // Don't forget to add ports. endmodule //////////////////////////////////////////////////////////////////////////////// /// Problem 2 /// // Convert a two-digit hex number in ASCII (12, af, 03) on "s" to binary // on "i" // Implicit Structural: assign and operators okay. // Test using test_atoi. module atoi_implicit(i,s); input [15:0] s; output [7:0] i; // Solution goes here. Can be done in two lines, but more are okay. endmodule //////////////////////////////////////////////////////////////////////////////// /// Problem 3 /// // Convert a two-digit hex number in ASCII (12, af, 03) on "s" to binary // on "i" // Explicit Structural: Use gates and modules only no assign or operators. // Can instantiate the following modules: and4, sub4, and8, sub8, see module // definitions below. // Test using test_atoi. module atoi_explicit(i,s); input [15:0] s; output [7:0] i; // Solution goes here. Can be done in two lines, but more are okay. endmodule // // Modules for use in Problem 3 // // DO NOT modify these modules. module sub4(d,a,b); input [3:0] a, b; output [3:0] d; assign d = a - b; endmodule module add4(d,a,b); input [3:0] a, b; output [3:0] d; assign d = a + b; endmodule module sub8(d,a,b); input [7:0] a, b; output [7:0] d; assign d = a - b; endmodule module add8(d,a,b); input [7:0] a, b; output [7:0] d; assign d = a + b; endmodule //////////////////////////////////////////////////////////////////////////////// /// Testbenches /// module test_decoder(); parameter stop_on_error = 1; reg [1:0] a; wire x0, x1, x2, x3; reg [3:0] x; decode_2_to_4 your_decoder(x0,x1,x2,x3,a); integer i, err; initial begin err = 0; for(i=0; i<4; i=i+1) begin a = i[1:0]; #1; x = 1 << a; if( {x3,x2,x1,x0} !== x ) begin \$display("FAIL: Demux wrong output for input %d",a); err = err + 1; if( stop_on_error ) \$stop; end end if( !err ) \$write("PASS: "); \$write("Tests completed, "); if( err ) \$display("encountered %d errors.",err); else \$display("no errors found.\n"); \$display("Thank you for using the decode testbench."); end endmodule module test_atoi(); wire [7:0] ie, ii; reg [15:0] s; parameter stop_on_error = 1; parameter ascii_0 = 48; parameter ascii_a = 97; atoi_explicit our_atoi_explicit(ie,s); atoi_implicit our_atoi_implict(ii,s); integer i, err_i, err_e; integer d0, d1; initial begin err_i = 0; err_e = 0; for(i=0; i<256; i=i+1) begin d0 = i & 15; d1 = i >> 4; s[7:0] = d0 < 10 ? d0 + ascii_0 : d0 + ascii_a - 10; s[15:8] = d1 < 10 ? d1 + ascii_0 : d1 + ascii_a - 10; #1; if( ie !== i ) begin \$display("FAIL: Explicit, wrong output, 0x%h (correct) != 0x%h", i,ie); err_e = err_e + 1; if( stop_on_error ) \$stop; end if( ii !== i ) begin \$display("FAIL: Implicit, wrong output, 0x%h (correct) != 0x%h", i,ii); err_i = err_i + 1; if( stop_on_error ) \$stop; end end if( !err_i ) \$write("PASS: "); \$write("Implicit tests completed, "); if( err_i ) \$display("encountered %d errors.",err_i); else \$display("no errors found.\n"); if( !err_e ) \$write("PASS: "); \$write("Explicit tests completed, "); if( err_e ) \$display("encountered %d errors.",err_e); else \$display("no errors found.\n"); end endmodule