ATO2-24: Created ID Issuing Module

hdl/src/sha256_id_issue.sv

+//-----------------------------------------------------------------------------
+// SoC Labs Basic SHA-256 1 to 3 Arbitrator
+// 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)
+//-----------------------------------------------------------------------------
+module sha256_id_issue (
+    input logic clk,
+    input logic nrst,
+    input logic en,
+    
+    // Synchronous, localised reset
+    input logic sync_rst,
+    
+    // Data In data and Handshaking - ID Seed
+    input  logic [5:0] seed_in,
+    input  logic seed_in_last,
+    input  logic seed_in_valid,
+    output logic seed_in_ready,
+    
+    // Data Out - ID Out
+    output logic [5:0] id_out,
+    output logic id_out_last,
+    output logic id_out_valid,
+    input  logic id_out_ready
+);
+    
+    logic state, next_state;
+        
+    logic [5:0] next_id_out;
+    logic next_id_out_last;
+    logic next_id_out_valid;
+    logic next_seed_in_ready;
+
+    
+    // State Machine Sequential Logic    
+    always_ff @(posedge clk, negedge nrst) begin
+        if ((!nrst) | sync_rst) begin
+            state            <= 1'd0;
+            seed_in_ready    <= 1'b0;
+            id_out           <= 6'd0;
+            id_out_last      <= 1'b0;
+            id_out_valid     <= 1'b0;
+        end else if (en == 1'b1) begin
+            state            <= next_state;
+            id_out           <= next_id_out;
+            id_out_last      <= next_id_out_last;
+            id_out_valid     <= next_id_out_valid;
+        end else begin
+            seed_in_ready    <= 1'b0;
+            id_out_valid     <= 1'b0;
+        end
+    end
+    
+    always_comb begin
+        // Default
+        next_state              = state;
+        next_seed_in_ready      = seed_in_ready;
+        next_id_out_valid       = id_out_valid;
+        next_id_out_last        = id_out_last;
+        next_id_out             = id_out;
+        
+        // Override
+        case (state)
+            1'd0: begin // Get Packet ID Seed
+                    next_seed_in_ready  = 1'b1;
+                    next_id_out_valid   = 1'b0;
+                    next_state          = 1'd1;
+                end
+                
+            1'd1: begin // Set Packet ID from Seed or Increment Value
+                     // Hold Ready, Valid and Last High throughout operation now
+                     // - if no data is seen on input, increment count
+                     // - if data is seen on input, count takes value of input
+                     // - there will always be valid data avaliable
+                    next_id_out_valid   = 1'b1; 
+                    next_seed_in_ready  = 1'b1;
+                    next_id_out_last    = 1'b1;
+                    // Check Inputs for Data
+                    if (seed_in_valid && seed_in_ready) begin
+                        // Valid Handshake and data can be processed
+                        // Write Input Data to Output 
+                        next_id_out = seed_in;
+                    end else begin
+                        next_id_out = id_out + 6'd1;
+                    end
+                end
+            
+            default: begin
+                    next_state = 1'd0;
+                end
+        endcase
+    end
+endmodule
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