1 files changed, 228 insertions, 0 deletions
diff --git a/src/prga.sv b/src/prga.sv
new file mode 100644
index 0000000..57f326f
--- /dev/null
+++ b/src/prga.sv
@@ -0,0 +1,228 @@
+module prga (
+	input logic clk,
+	input logic rst_n,
+	input logic en,
+	output logic rdy,
+	input logic [23:0] key,
+
+	output logic [7:0] s_addr,
+	input logic [7:0] s_rddata,
+	output logic [7:0] s_wrdata,
+	output logic s_wren,
+
+	output logic [7:0] ct_addr,
+	input logic [7:0] ct_rddata,
+
+	output logic [7:0] pt_addr,
+	input logic [7:0] pt_rddata,
+	output logic [7:0] pt_wrdata,
+	output logic pt_wren
+);
+
+	logic [7:0] i_d, i_q, j_d, j_q, k_d, k_q, si_d, si_q, sj_d, sj_q;
+	logic [7:0] length_d, length_q;
+
+	enum logic [3:0] {
+		INIT,
+		SET_LENGTH,
+		FETCH_I,
+		FETCH_J,
+		WRITE_I,
+		WRITE_J,
+		FETCH_PAD,
+		WRITE_PT,
+		DONE
+	} state_d, state_q;
+
+	always_comb begin: fsm_output_logic
+		rdy = '0;
+
+		i_d = i_q;
+		j_d = j_q;
+		k_d = k_q;
+		si_d = si_q;
+		sj_d = sj_q;
+		length_d = length_q;
+
+		unique case (state_q)
+			INIT: begin
+				rdy = '1;
+
+				s_addr = '0;
+				s_wrdata = '0;
+				s_wren = '0;
+
+				/* Fetch message length. */
+				ct_addr = '0;
+
+				pt_addr = '0;
+				pt_wrdata = '0;
+				pt_wren = '0;
+			end
+			SET_LENGTH: begin
+				length_d = ct_rddata;
+
+				rdy = '0;
+
+				s_addr = '0;
+				s_wrdata = '0;
+				s_wren = '0;
+
+				ct_addr = '0;
+
+				pt_addr = '0;
+				pt_wrdata = ct_rddata;
+				pt_wren = '1;
+			end
+			FETCH_I: begin
+				i_d = i_q + 1'b1;
+
+				rdy = '0;
+
+				s_addr = i_d;
+				s_wrdata = '0;
+				s_wren = '0;
+
+				ct_addr = '0;
+
+				pt_addr = '0;
+				pt_wrdata = '0;
+				pt_wren = '0;
+			end
+			/* s_rddata now contains s[i]. */
+			FETCH_J: begin
+				/* Calculate j. */
+				j_d = j_q + s_rddata;
+
+				/* Save s[i]. */
+				si_d = s_rddata;
+
+				rdy = '0;
+
+				s_addr = j_d;
+				s_wrdata = '0;
+				s_wren = '0;
+
+				ct_addr = '0;
+
+				pt_addr = '0;
+				pt_wrdata = '0;
+				pt_wren = '0;
+			end
+			/* s_rddata now contains s[j]. */
+			WRITE_I: begin
+				/* Save s[j]. */
+				sj_d = s_rddata;
+
+				rdy = '0;
+
+				s_addr = j_d;
+				s_wrdata = si_q;
+				s_wren = '1;
+
+				ct_addr = '0;
+
+				pt_addr = '0;
+				pt_wrdata = '0;
+				pt_wren = '0;
+			end
+			WRITE_J: begin
+				rdy = '0;
+
+				s_addr = i_d;
+				s_wrdata = sj_q;
+				s_wren = '1;
+
+				ct_addr = '0;
+
+				pt_addr = '0;
+				pt_wrdata = '0;
+				pt_wren = '0;
+			end
+			FETCH_PAD: begin
+				rdy = '0;
+
+				s_addr = si_q + sj_q;
+				s_wrdata = '0;
+				s_wren = '0;
+
+				ct_addr = k_q;
+
+				pt_addr = '0;
+				pt_wrdata = '0;
+				pt_wren = '0;
+			end
+			WRITE_PT: begin
+				k_d = k_q + 1'b1;
+
+				rdy = '0;
+
+				s_addr = '0;
+				s_wrdata = '0;
+				s_wren = '0;
+
+				ct_addr = '0;
+
+				pt_addr = k_q;
+				pt_wrdata = s_rddata ^ ct_rddata;
+				pt_wren = '1;
+			end
+			DONE: begin
+				rdy = '1;
+
+				s_addr = '0;
+				s_wrdata = '0;
+				s_wren = '0;
+
+				ct_addr = '0;
+
+				pt_addr = '0;
+				pt_wrdata = '0;
+				pt_wren = '0;
+			end
+			default: begin end
+		endcase
+	end: fsm_output_logic
+
+	always_comb begin: fsm_next_state_logic
+		unique case (state_q)
+			INIT: begin
+				if (rdy && en) state_d = SET_LENGTH;
+				else state_d = INIT;
+			end
+			SET_LENGTH: state_d = FETCH_I;
+			FETCH_I: state_d = FETCH_J;
+			FETCH_J: state_d = WRITE_I;
+			WRITE_I: state_d = WRITE_J;
+			WRITE_J: state_d = FETCH_PAD;
+			FETCH_PAD: state_d = WRITE_PT;
+			WRITE_PT: begin
+				if (k_q == length_q) state_d = DONE;
+				else state_d = FETCH_I;
+			end
+			DONE: state_d = DONE;
+			default: state_d = INIT;
+		endcase
+	end: fsm_next_state_logic
+
+	always_ff @(posedge clk) begin: fsm_reg
+		if (~rst_n) begin
+			state_q <= INIT;
+			i_q <= '0;
+			j_q <= '0;
+			k_q <= 1'b1;
+			si_q <= '0;
+			sj_q <= '0;
+			length_q <= '0;
+		end else begin
+			state_q <= state_d;
+			i_q <= i_d;
+			j_q <= j_d;
+			k_q <= k_d;
+			si_q <= si_d;
+			sj_q <= sj_d;
+			length_q <= length_d;
+		end
+	end: fsm_reg
+
+endmodule: prga