Added primitive decode stage, improved state handling and fixed CIR register

8086_documentation.md

@@ -51,8 +51,8 @@ Example instructions:
 
 |  Bytecode  |   AT&T Syntax   |                         meaning                            |
 | ---------- | --------------- | ---------------------------------------------------------- |
-|81 c0 aa 55 | add $0x55aa,%ax | write 0x55aa to register ax                                |
-|03 06 aa 55 | add 0x55aa,%ax  | write the contents of memory locaton 0x55aa to register ax |
+|81 c0 aa 55 | add $0x55aa,%ax | add 0x55aa to register ax                                  |
+|03 06 aa 55 | add 0x55aa,%ax  | add the contents of memory locaton 0x55aa to register ax   |
 |fe c0       | inc %al         | increment register al                                      |
 |ff c0       | inc %ax         | increment register ax                                      |
 |40          | inc %ax         | increment register ax                                      |

cpu/gtkwave_savefile.gtkw

@@ -1,32 +1,34 @@
 [*]
 [*] GTKWave Analyzer v3.3.104 (w)1999-2020 BSI
-[*] Wed Feb  8 23:43:14 2023
+[*] Thu Feb  9 14:44:08 2023
 [*]
 [dumpfile] "/home/user/UNI_DATA/COMS30046_2022_TB-2/projects/9086/cpu/test.lx2"
-[dumpfile_mtime] "Wed Feb  8 23:42:51 2023"
-[dumpfile_size] 470
+[dumpfile_mtime] "Thu Feb  9 14:43:59 2023"
+[dumpfile_size] 757
 [savefile] "/home/user/UNI_DATA/COMS30046_2022_TB-2/projects/9086/cpu/gtkwave_savefile.gtkw"
 [timestart] 0
-[size] 1534 1059
+[size] 1630 1059
 [pos] -1 -1
-*-20.795050 2883000 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
+*-22.795050 2010000 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
 [treeopen] tb.
 [sst_width] 221
 [signals_width] 293
 [sst_expanded] 1
 [sst_vpaned_height] 313
-@28
-tb.p.clock[0]
-tb.p.reset[0]
-tb.p.start[0]
 @29
-tb.p.state[2:0]
+tb.p.clock[0]
 @28
-tb.p.instruction_finished[0]
+tb.p.reset[0]
 @22
+tb.p.state[3:0]
 tb.p.external_address_bus[19:0]
 tb.p.external_data_bus[15:0]
+tb.p.CIR[15:0]
 @28
-tb.p.read[0]
+tb.p.EXCEPTION[0]
+tb.p.ADD_INST[0]
+tb.p.INC_INST[0]
+@22
+tb.p.PARAM1[15:0]
 [pattern_trace] 1
 [pattern_trace] 0

cpu/proc_state_def.v

@@ -0,0 +1,12 @@
+`define PROC_HALT_STATE		4'b0000
+
+/*INSTRUCTION FETCH STATE*/
+`define PROC_IF_STATE_ENTRY	4'b0001
+`define PROC_IF_WRITE_CIR	4'b0010
+
+/*DECODE SATE*/
+`define PROC_DE_STATE_ENTRY	4'b0100
+`define PROC_DE_LOAD_16_PARAM	4'b0101
+
+/*EXECUTE STATE*/
+`define PROC_EX_STATE_ENTRY	4'b1000

cpu/processor.v

@@ -1,4 +1,5 @@
 `timescale 1ns/1ps
+`include "proc_state_def.v"
 
 module clock_gen (input enable, output reg clk);
 
@@ -52,53 +53,103 @@ end
 endmodule
 
 
-module processor ( input clock, input reset , output reg [19:0] external_address_bus, inout [15:0] external_data_bus,output reg read, output reg write);
+module processor ( input clock, input reset , output reg [19:0] external_address_bus, inout [15:0] external_data_bus,output reg read, output reg write, output reg HALT);
 /* State */
-reg [2:0] state;
-reg start=0;
+reg [3:0] state;
 reg instruction_finished;
 
 /* Registers */
 reg [19:0] ProgCount;
-reg [14:0] CIR;
+reg [15:0] CIR;
+reg [15:0] PARAM1;
+reg [15:0] PARAM2;
 
 /* RESET LOGIC */
 always @(negedge reset) begin
 	if (reset==0) begin
 		@(posedge clock);
-		state=0;
 		ProgCount=0;//TODO: Reset Vector
-		#10
-		start=1;
+		ADD_INST=0;
+		EXCEPTION=0;
+		INC_INST=0;
+		HALT=0;
+		@(negedge clock);
+		@(posedge clock);
+		state=`PROC_IF_STATE_ENTRY;
 	end
 end
 
-/* CLOCK LOGIC */
-always @(posedge clock) begin
-	if(instruction_finished)
-		state =0;
-	else
-		if (clock && start==1)
-			state=state+1;
-end
-
-always @(state) begin
-	if (state==5)
-		instruction_finished=1;
-	else
-		instruction_finished=0;
-end
-
 /* Processor stages */
-always @(state) begin
-	if (state=='b000) begin
-		external_address_bus <= ProgCount;
-		read <= 0;
-		write <= 1;
-	end else if ( state=='b001 ) begin
-		CIR <= external_data_bus;
-		ProgCount=ProgCount+1;
-	end
+reg ADD_INST,EXCEPTION,INC_INST;
+
+always @(negedge clock) begin
+	case(state)
+		`PROC_IF_WRITE_CIR:begin
+			CIR <= external_data_bus;
+			ProgCount=ProgCount+1;
+			state=`PROC_DE_STATE_ENTRY;
+		end
+	endcase
+end
+
+always @(posedge clock) begin
+	case(state)
+		`PROC_HALT_STATE:
+			HALT=1;
+		`PROC_IF_STATE_ENTRY:begin
+			external_address_bus <= ProgCount;
+			read <= 0;
+			write <= 1;
+			state=`PROC_IF_WRITE_CIR;
+		end
+		`PROC_DE_STATE_ENTRY:begin
+			external_address_bus <= ProgCount; /*Remenance from IF*/
+			case(CIR[15:10])
+				6'b100000 : begin
+					case (CIR[5:3])
+						3'b000 :begin
+							ADD_INST=1;
+							state=`PROC_DE_LOAD_16_PARAM;
+						end
+						default:begin
+							EXCEPTION=1;
+							state=`PROC_EX_STATE_ENTRY;
+						end
+					endcase
+				end
+				6'b111111 : begin
+					if (CIR[9:9] == 1 ) begin
+						case (CIR[5:3])
+							3'b000 :begin
+								INC_INST=1;
+								state=`PROC_EX_STATE_ENTRY;
+							end
+							default:begin
+								EXCEPTION=1;
+								state=`PROC_EX_STATE_ENTRY;
+							end
+						endcase
+					end else begin
+						EXCEPTION=1;
+						state=`PROC_EX_STATE_ENTRY;
+					end
+				end
+				default:begin
+					EXCEPTION=1;
+					state=`PROC_EX_STATE_ENTRY;
+				end
+			endcase
+		end
+		`PROC_DE_LOAD_16_PARAM:begin
+			PARAM1 <= external_data_bus;
+			ProgCount=ProgCount+1;
+			state=`PROC_EX_STATE_ENTRY;
+		end
+		`PROC_EX_STATE_ENTRY:begin
+			EXCEPTION=0;ADD_INST=0;INC_INST=0;
+			state=`PROC_IF_STATE_ENTRY;
+		end
+	endcase
 end
 
 endmodule

cpu/testbench.v

@@ -4,9 +4,9 @@ reg reset;
 reg  clk_enable;
 wire [19:0]address_bus;
 wire [15:0]data_bus;
-wire rd,wr,romcs;
+wire rd,wr,romcs,HALT;
 
-processor p(clock,reset,address_bus,data_bus,rd,wr);
+processor p(clock,reset,address_bus,data_bus,rd,wr,HALT);
 rom bootrom(address_bus,data_bus,rd,romcs);
 
 `define CPU_SPEED 1000
@@ -22,7 +22,7 @@ initial begin
 
 	#($random%500)
 	reset = 0;
-	#(100) 
+	#(`CPU_SPEED) 
 	reset = 1;
 	#(`CPU_SPEED*30)