diff --git a/.DS_Store b/.DS_Store
index b6fcc25b02128d8d68590a95cd6b43f435142f0c..617ce0426920c16bba8d96c7d48c2a8973b5490f 100644
Binary files a/.DS_Store and b/.DS_Store differ
diff --git a/hdl/verif/tb_sha256_id_buf.sv b/hdl/verif/tb_sha256_id_buf.sv
new file mode 100644
index 0000000000000000000000000000000000000000..e49f82fec55ebd099071a880ecfbf4be384a541f
--- /dev/null
+++ b/hdl/verif/tb_sha256_id_buf.sv
@@ -0,0 +1,244 @@
+//-----------------------------------------------------------------------------
+// SoC Labs Basic SHA-2 ID Buffer Testbench
+// A joint work commissioned on behalf of SoC Labs, under Arm Academic Access license.
+//
+// Contributors
+//
+// David Mapstone (d.a.mapstone@soton.ac.uk)
+//
+// Copyright 2022, SoC Labs (www.soclabs.org)
+//-----------------------------------------------------------------------------
+`timescale 1ns/1ns
+`include "sha256_id_buf.sv"
+
+module tb_sha256_id_buf;
+
+ logic clk;
+ logic nrst;
+ logic en;
+ logic sync_rst;
+
+ // ID Buffer IN
+ logic [5:0] id_in;
+ logic id_in_last;
+ logic id_in_valid;
+ logic id_in_ready;
+
+ // ID Out
+ logic [5:0] id_out;
+ logic id_out_last;
+ logic id_out_valid;
+ logic id_out_ready;
+
+ // Status Out - Gets updated after every hash
+ logic [5:0] status_id;
+
+
+ sha256_id_buf uut (
+ .clk (clk),
+ .nrst (nrst),
+ .en (en),
+ .sync_rst (sync_rst),
+
+ // ID IN
+ .id_in (id_in),
+ .id_in_last (id_in_last),
+ .id_in_valid (id_in_valid),
+ .id_in_ready (id_in_ready),
+
+ // ID Out
+ .id_out (id_out),
+ .id_out_last (id_out_last),
+ .id_out_valid (id_out_valid),
+ .id_out_ready (id_out_ready),
+
+ // Status Out - Gets updated on every output Handshake
+ .status_id (status_id)
+ );
+
+ logic id_in_drive_en;
+
+ logic id_out_drive_ready;
+
+ logic [5:0] id_in_queue [$];
+ logic id_in_last_queue [$];
+ int id_in_gap_queue [$];
+ logic id_in_wait_queue;
+
+ logic [5:0] id_out_queue [$];
+ logic id_out_last_queue [$];
+ int id_out_stall_queue [$];
+ logic id_out_wait_queue;
+
+ // TODO: Handle Status Checking
+
+ // Handle Valid and Data for id_in
+ always_ff @(posedge clk, negedge nrst) begin: id_in_valid_drive
+ if (!nrst) begin
+ id_in <= 6'd0;
+ id_in_valid <= 1'b0;
+ id_in_last <= 1'b0;
+ id_in_gap <= 0;
+ id_in_wait_queue <= 1'b1;
+ end else if (id_in_drive_en) begin
+ if (id_in_gap > 1) begin
+ id_in_gap <= id_in_gap - 1;
+ id_in_valid <= 1'b0;
+ end else begin
+ id_in_valid <= 1'b1;
+ end
+ if (((id_in_valid == 1'b1) && (id_in_ready == 1'b1)) ||
+ (id_in_wait_queue == 1'b1)) begin
+ // Data transfer just completed or transfers already up to date
+ if ((id_in_queue.size() > 0) && (id_in_last_queue.size() > 0) && (id_in_gap_queue.size() > 0)) begin
+ id_in <= id_in_queue.pop_front();
+ id_in_last <= id_in_last_queue.pop_front();
+ if (id_in_gap_queue[0] == 0) begin
+ id_in_valid <= 1'b1;
+ end else begin
+ id_in_valid <= 1'b0;
+ end
+ id_in_gap <= id_in_gap_queue.pop_front();
+ id_in_wait_queue <= 1'b0;
+ end else begin
+ // No data currently avaiable in queue to write but transfers up to date
+ id_in_wait_queue <= 1'b1;
+ id_in_valid <= 1'b0;
+ end
+ end
+ end
+ end
+
+ logic [5:0] id_out_check;
+ logic id_out_last_check;
+
+ int id_in_gap;
+ int id_out_stall;
+
+ int packet_num;
+
+ // Handle Output Ready Signal Verification
+ always @(posedge clk) begin
+ // Check Override Control on Ready
+ if (id_out_drive_ready) begin
+ // Count down to zero before enabling Ready
+ if (id_out_stall > 1) begin
+ id_out_stall <= id_out_stall - 1;
+ id_out_ready <= 1'b0;
+ end else begin
+ // Wait for handshake before updating stall value
+ if ((id_out_valid == 1'b1) && (id_out_ready == 1'b1)) begin
+ if (id_out_stall_queue.size() > 0) begin
+ if (id_out_stall_queue[0] == 0) begin
+ id_out_ready <= 1'b1;
+ end else begin
+ id_out_ready <= 1'b0;
+ end
+ id_out_stall <= id_out_stall_queue.pop_front();
+ end
+ // Keep Ready Asserted until handshake seen
+ end else begin
+ id_out_ready <= 1'b1;
+ end
+ end
+ end else begin
+ id_out_ready <= 1'b0;
+ end
+ end
+
+ // Handle Output Data Verification
+ always @(posedge clk) begin
+ // Check Data on Handshake
+ if ((id_out_valid == 1'b1) && (id_out_ready == 1'b1)) begin
+ // Check Size
+ assert (id_out == id_out_check) else begin
+ $error("id_out missmatch! packet %d | recieve: %x != check: %x", packet_num, id_out, id_out_check);
+ $finish;
+ end
+ if ($test$plusargs ("DEBUG")) $display("id_out match! packet %d | recieve: %x == check: %x", packet_num, id_out, id_out_check);
+
+ // Check Last Flag
+ assert (id_out_last == id_out_last_check) else begin
+ $error("id_out_last missmatch! packet %d | recieve: %x != check: %x", packet_num, id_out_last, id_out_last_check);
+ $finish;
+ end
+ if ($test$plusargs ("DEBUG")) $display("id_out_last match! packet %d | recieve: %x == check: %x", packet_num, id_out_last, id_out_last_check);
+
+ // Pop new values
+ if ((id_out_queue.size() > 0) && (id_out_last_queue.size() > 0)) begin
+ id_out_check <= id_out_queue.pop_front();
+ id_out_last_check <= id_out_last_queue.pop_front();
+ if (id_out_last_check == 1'b1) begin
+ packet_num <= packet_num + 1;
+ end
+ end else begin
+ $display("Test Passes");
+ $finish;
+ end
+ end
+ end
+
+ // File Reading Variables
+ int fd; // File descriptor Handle
+
+ logic [5:0] temp_id_in; // Temporary Input Data Storage
+ logic temp_id_in_last; // Temporary Input Data Last
+ int temp_id_in_gap; // Temporary Input Gap
+
+ logic [5:0] temp_id_out; // Temporary Hash Value
+ logic temp_id_out_last; // Temporary Hash last;
+ int temp_id_out_stall; // Temporary Hash stall;
+
+ initial begin
+ $dumpfile("sha256_id_buf.vcd");
+ $dumpvars(0, tb_sha256_id_buf);
+ id_in_drive_en = 0;
+ id_out_drive_ready = 0;
+
+ // Read input data into Queue in
+ fd = $fopen("../stimulus/testbench/input_validator_id_stim.csv", "r");
+ while ($fscanf (fd, "%d,%b,%d", temp_id_in, temp_id_in_last, temp_id_in_gap) == 3) begin
+ id_in_queue.push_back(temp_id_in);
+ id_in_last_queue.push_back(temp_id_in_last);
+ id_in_gap_queue.push_back(temp_id_in_gap);
+ end
+ $fclose(fd);
+
+ // Read output data into Queue
+ fd = $fopen("../stimulus/testbench/output_id_out_ref.csv", "r");
+ while ($fscanf (fd, "%x,%b,%b,%d", temp_id_out, temp_id_out_last, temp_id_out_stall) == 3) begin
+ id_out_queue.push_back(temp_id_out);
+ id_out_last_queue.push_back(temp_id_out_last);
+ id_out_stall_queue.push_back(temp_id_out_stall);
+ end
+ $fclose(fd);
+
+ // Initialise First Checking Values
+ id_out_check = id_out_queue.pop_front();
+ id_out_last_check = id_out_last_queue.pop_front();
+ id_out_stall = id_out_stall_queue.pop_front();
+
+ // Defaultly enable Message Builder
+ en = 1;
+
+ // Defaultly set Sync Reset Low
+ sync_rst = 0;
+
+ #20 nrst = 1;
+ #20 nrst = 0;
+ #20 nrst = 1;
+
+ // Write some data into the config register
+ # 30 id_in_drive_en = 1;
+
+ # 30 id_out_drive_ready = 1;
+ end
+
+ initial begin
+ forever begin
+ #10 clk = 0;
+ #10 clk = 1;
+ end
+ end
+
+endmodule
\ No newline at end of file