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cse141L-project/RTL/program1_tb.sv

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2022-08-15 17:48:23 +00:00
// program1_tb
// testbench for programmable message encryption (Program #1)
// CSE141L
// runs program 1 (encrypt a message)
module program1_tb ();
// DUT interface -- four one-bit wires, three to DUT, one from
bit clk; // advances simulation step-by-step
bit init = 1'b1; // init (reset) command to DUT
bit start = 1'b1; // request (start program) command to DUT
wire done; // acknowledge (program done) flag returned by DUT
// test bench parameters
logic [7:0] pre_length; // number of space char. before message itself, sent to data_mem[61]
logic [7:0] message1[54]; // original raw message, in binary, up to 54 characters in length
logic [7:0] msg_padded1[64]; // original message, plus pre- and post-padding w/ ASCII spaces
logic [7:0] msg_crypto1[64]; // encrypted message returned by DUT
logic [7:0] lfsr_ptrn; // choses one of 9 maximal length 7-tap shift reg. patterns
logic [7:0] LFSR_ptrn[9]; // the 9 candidate maximal-length 7-bit LFSR tap ptrns themselves
logic [7:0] lfsr1[64]; // states of program 1 encrypting LFSR
logic [7:0] LFSR_init; // one of 127 possible NONZERO starting states for encrypting LFSR
int score; // count of correctly encyrpted characters
// our original American Standard Code for Information Interchange message follows
// note in practice your design should be able to handle ANY ASCII string that is
// restricted to characters between space (0x20) and script f (0x9f) and shorter than
// 55 characters in length
string str1 = "Mr. Watson, come here. I want to see you.";
// displayed encrypted string will go here:
string str_enc1[64]; // program 1 desired output will go here
int strlen; // length of incoming message string itself, before padding
logic [3:0] pt_no; // select LFSR pattern, index value 0 through 8
int file_no; // output file tag (set to 1 for write to console/transcript)
// the 9 possible 7-tap maximal-length feedback tap patterns from which to choose
assign LFSR_ptrn[0] = 8'h60;
assign LFSR_ptrn[1] = 8'h48;
assign LFSR_ptrn[2] = 8'h78;
assign LFSR_ptrn[3] = 8'h72;
assign LFSR_ptrn[4] = 8'h6A;
assign LFSR_ptrn[5] = 8'h69;
assign LFSR_ptrn[6] = 8'h5C;
assign LFSR_ptrn[7] = 8'h7E;
assign LFSR_ptrn[8] = 8'h7B;
always_comb begin
pt_no = $random;
if(pt_no>8) pt_no[3] = 0; // restrict pt_no to 0 through 8
lfsr_ptrn = LFSR_ptrn[pt_no]; // look up and engage the selected pattern; to data_mem[62]
end
// now select a starting LFSR state -- any nonzero value will do
always_comb begin
LFSR_init = $random;
if(!LFSR_init) LFSR_init = 7'b1; // prevents illegal starting state = 7'b0;
end
// set preamble length for the program run (always > 9 but < 26)
always_comb begin
pre_length = $random;
if(pre_length < 10) pre_length = 10; // prevents pre_length < 10
else if(pre_length > 26) pre_length = 26; // prevets pre_length > 26
end
// ***** instantiate your own top level design here *****
top_level dut(
.clk(clk), // input: use your own port names, if different
.init(init), // input: some prefer to call this ".reset"
.req(start), // input: launch program
.ack(done) // output: "program run complete"
);
initial begin
file_no = 'b1;
//file_no = $fopen("msg_enocder_out.txt","w");
#0ns strlen = str1.len; // length of string 1 (# characters between " ")
if(strlen>54) strlen = 54; // clip message at 54 characters
// program 1 -- precompute encrypted message
lfsr1[0] = LFSR_init; // any nonzero value (zero may be helpful for debug)
$fdisplay(file_no,"run encryption program; original message = ");
$fdisplay(file_no,"%s",str1); // print original message in transcript window
$fdisplay(file_no,"pt_no = %d",pt_no);
$fdisplay(file_no,"LFSR_ptrn = 0x%h, LFSR_init = 0x%h",lfsr_ptrn,LFSR_init);
// will subtract 0x20 from each preamble and each message character
for(int j=0; j<64; j++) // pre-fill message_padded with ASCII space characters
msg_padded1[j] = 8'h20; //
for(int l=0; l<strlen; l++) // overwrite up to 54 of these spaces w/ message itself
msg_padded1[pre_length+l] = str1[l]; // test bench does the -0x20 offset now
// compute and store the LFSR sequence
for (int ii=0;ii<63;ii++)
lfsr1[ii+1] = {(lfsr1[ii][5:0]),(^(lfsr1[ii]&lfsr_ptrn))};
// encrypt the message character-by-character, then prepend the parity
// testbench will change on falling clocks to avoid race conditions at rising clocks
for (int i=0; i<64; i++) begin
msg_crypto1[i] = ((msg_padded1[i]-32) ^ lfsr1[i]);
msg_crypto1[i][7] = 'b0;//^msg_crypto1[i][6:0]; // prepend parity bit into MSB
$fdisplay(file_no,"i=%d, msg_pad=0x%h, lfsr=%b msg_crypt w/ parity = 0x%h", i,msg_padded1[i],lfsr1[i],msg_crypto1[i]);
// for display purposes only, add 8'h20 to avoid nonprintable characters (<8'h20)
str_enc1[i] = string'(msg_crypto1[i][6:0]+'h20);
end
$fdisplay(file_no,"encrypted string = ");
for(int jj=0; jj<64; jj++)
$fwrite(file_no,"%s",str_enc1[jj]);
$fdisplay(file_no,"\n");
// run encryption program
// ***** load operands into your data memory *****
// ***** use your instance name for data memory and its internal core *****
for(int m=0; m<61; m++)
dut.DM.core[m] = 8'h0; // pad memory w/ ASCII space characters
for(int m=0; m<strlen; m++)
dut.DM.core[m] = (str1[m]-8'h20); // overwrite/copy original string into device's data memory[0:strlen-1]
dut.DM.core[61] = pre_length; // number of bytes preceding message
dut.DM.core[62] = lfsr_ptrn; // LFSR feedback tap positions (9 permissible patterns)
dut.DM.core[63] = LFSR_init; // LFSR starting state (nonzero)
#20ns init = 1'b0; // suggestion: reset = 1 forces your program counter to 0
#10ns start = 1'b0; // request/start = 1 holds your program counter
#60ns; // wait for 6 clock cycles of nominal 10ns each
wait(done); // wait for DUT's ack/done flag to go high
#10ns $fdisplay(file_no,"");
$fdisplay(file_no,"program 1:");
// ***** reads your results and compares to test bench
// ***** use your instance name for data memory and its internal core *****
// the +'h20 restores the -32 bias, for better display visuals
for(int n=0; n<64; n++) begin
if(msg_crypto1[n]==dut.DM.core[n+64]) begin
$fdisplay(file_no,"%d bench msg: %s %h dut msg: %h", n, msg_crypto1[n][6:0]+8'h20, msg_crypto1[n], dut.DM.core[n+64]);
score++;
end
else
$fdisplay(file_no,"%d bench msg: %s %h dut msg: %h OOPS!", n, msg_crypto1[n][6:0]+8'h20, msg_crypto1[n], dut.DM.core[n+64]);
end
$fdisplay(file_no,"score = %d/64",score);
#20ns $fclose(file_no);
#20ns $stop;
end
always begin // continuous loop
#5ns clk = 1; // clock tick
#5ns clk = 0; // clock tock
end
endmodule