Added a very basic execution stage, registers and a very crude adder for ALU. It finally executes instructions!

cpu/Makefile

@@ -1,4 +1,5 @@
-SOURCES=processor.v testbench.v memory.v
+SOURCES=processor.v testbench.v memory.v registers.v alu.v
+INCLUDES=proc_state_def.v
 VVP=processor.vvp
 
 .PHONY: run
@@ -13,8 +14,8 @@ wave: ${VVP}
 	vvp ${VVP} -lxt2
 	gtkwave test.lx2 gtkwave_savefile.gtkw
 
-${VVP} : ${SOURCES}
-	iverilog -g2012 $^ -o $@
+${VVP} : ${SOURCES} ${INCLUDES}
+	iverilog -g2012 ${SOURCES} -o $@
 
 .PHONY: clean
 clean:

cpu/alu.v

@@ -0,0 +1,9 @@
+module ADDER16(input [15:0]A,input [15:0]B, input oe,output [15:0]OUT, output carry);
+wire c;
+wire [15:0]sum;
+assign {c,sum} = A+B;
+
+assign OUT = !oe ? sum : 16'hz;
+assign carry = !oe ? c : 'hz;
+
+endmodule

cpu/gtkwave_savefile.gtkw

@@ -1,34 +1,56 @@
 [*]
 [*] GTKWave Analyzer v3.3.104 (w)1999-2020 BSI
-[*] Thu Feb  9 14:44:08 2023
+[*] Thu Feb  9 20:13:04 2023
 [*]
 [dumpfile] "/home/user/UNI_DATA/COMS30046_2022_TB-2/projects/9086/cpu/test.lx2"
-[dumpfile_mtime] "Thu Feb  9 14:43:59 2023"
-[dumpfile_size] 757
+[dumpfile_mtime] "Thu Feb  9 20:10:34 2023"
+[dumpfile_size] 1043
 [savefile] "/home/user/UNI_DATA/COMS30046_2022_TB-2/projects/9086/cpu/gtkwave_savefile.gtkw"
 [timestart] 0
-[size] 1630 1059
+[size] 1438 1059
 [pos] -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
+*-22.795050 6163000 -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.
+[treeopen] tb.p.
+[treeopen] tb.p.exec_units.
 [sst_width] 221
 [signals_width] 293
 [sst_expanded] 1
 [sst_vpaned_height] 313
-@29
-tb.p.clock[0]
 @28
+tb.p.clock[0]
 tb.p.reset[0]
-@22
 tb.p.state[3:0]
+@22
 tb.p.external_address_bus[19:0]
 tb.p.external_data_bus[15:0]
 tb.p.CIR[15:0]
 @28
 tb.p.EXCEPTION[0]
-tb.p.ADD_INST[0]
-tb.p.INC_INST[0]
+@c00022
+tb.p.exec_units.ADDER16_1.A[15:0]
+@28
+(0)tb.p.exec_units.ADDER16_1.A[15:0]
+(1)tb.p.exec_units.ADDER16_1.A[15:0]
+(2)tb.p.exec_units.ADDER16_1.A[15:0]
+(3)tb.p.exec_units.ADDER16_1.A[15:0]
+(4)tb.p.exec_units.ADDER16_1.A[15:0]
+(5)tb.p.exec_units.ADDER16_1.A[15:0]
+(6)tb.p.exec_units.ADDER16_1.A[15:0]
+(7)tb.p.exec_units.ADDER16_1.A[15:0]
+(8)tb.p.exec_units.ADDER16_1.A[15:0]
+(9)tb.p.exec_units.ADDER16_1.A[15:0]
+(10)tb.p.exec_units.ADDER16_1.A[15:0]
+(11)tb.p.exec_units.ADDER16_1.A[15:0]
+(12)tb.p.exec_units.ADDER16_1.A[15:0]
+(13)tb.p.exec_units.ADDER16_1.A[15:0]
+(14)tb.p.exec_units.ADDER16_1.A[15:0]
+(15)tb.p.exec_units.ADDER16_1.A[15:0]
+@1401200
+-group_end
 @22
-tb.p.PARAM1[15:0]
+tb.p.exec_units.ADDER16_1.B[15:0]
+@29
+tb.p.exec_units.register_file.write1[0]
 [pattern_trace] 1
 [pattern_trace] 0

cpu/proc_state_def.v

@@ -10,3 +10,4 @@
 
 /*EXECUTE STATE*/
 `define PROC_EX_STATE_ENTRY	4'b1000
+`define PROC_EX_STATE_EXIT	4'b1001

cpu/processor.v

@@ -1,6 +1,38 @@
 `include "proc_state_def.v"
 
+module exec_units ( input [15:0]PARAM1, input [15:0]PARAM2, input [1:0]in1_sel, input [1:0]in2_sel, input [1:0]out_sel , input EXEC);
+/*Architectural Register file*/
+wire [2:0] reg_addr;
+wire [15:0] reg_data;
+wire reg_read;
+wire reg_write;
+wire [2:0] reg_read_addr;
+wire [15:0] reg_read_data;
+wire reg_read_read;
+register_file register_file(reg_addr,reg_data,reg_read,reg_write,reg_read_addr,reg_read_data,reg_read_read);
+
+/*Exec Unts*/
+wire [15:0] ADDER16_1A;
+wire [15:0] ADDER16_1B;
+wire [15:0] ADDER16_1O;
+wire ADDER16_1C;
+ADDER16 ADDER16_1(ADDER16_1A,ADDER16_1B,EXEC,ADDER16_1O,ADDER16_1C);
+
+/*logic*/
+assign reg_addr=PARAM2[5:3];
+assign reg_read=EXEC;
+assign reg_write=EXEC;
+assign reg_read_read=0;
+assign reg_read_addr=PARAM2[2:0];
+assign ADDER16_1A= (in1_sel==2'b00) ? PARAM1 : 16'b1010101010101010;
+assign ADDER16_1B= (in2_sel==2'b01) ? reg_read_data : 16'b1010101010101010;
+//assign reg_data = (out_sel==2'b01) ? ADDER16_1O : 'hz;
+//assign reg_data = (out_sel==2'b01) ? ADDER16_1O : ADDER16_1O;
+assign reg_data = ADDER16_1O;
+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, output reg HALT);
+
 /* State */
 reg [3:0] state;
 reg instruction_finished;
@@ -11,24 +43,30 @@ reg [15:0] CIR;
 reg [15:0] PARAM1;
 reg [15:0] PARAM2;
 
+/* Execution units*/
+reg [1:0] in1_sel;
+reg [1:0] in2_sel;
+reg [1:0] out_sel;
+reg exec_unit_execute;
+exec_units exec_units(PARAM1,PARAM2,in1_sel,in2_sel,out_sel,exec_unit_execute);
+
 /* RESET LOGIC */
 always @(negedge reset) begin
 	if (reset==0) begin
 		@(posedge clock);
 		ProgCount=0;//TODO: Reset Vector
-		ADD_INST=0;
 		EXCEPTION=0;
-		INC_INST=0;
 		HALT=0;
+		exec_unit_execute=1;
 		@(negedge clock);
 		@(posedge clock);
 		state=`PROC_IF_STATE_ENTRY;
 	end
 end
 
-/* Processor stages */
-reg ADD_INST,EXCEPTION,INC_INST;
+reg EXCEPTION;
 
+/* Processor stages */
 always @(negedge clock) begin
 	case(state)
 		`PROC_IF_WRITE_CIR:begin
@@ -36,14 +74,21 @@ always @(negedge clock) begin
 			ProgCount=ProgCount+1;
 			state=`PROC_DE_STATE_ENTRY;
 		end
+		`PROC_EX_STATE_EXIT:begin
+			exec_unit_execute=1;
+			state=`PROC_IF_STATE_ENTRY;
+		end
 	endcase
 end
 
+`define invalid_instruction state=`PROC_IF_STATE_ENTRY;EXCEPTION=1;
+
 always @(posedge clock) begin
 	case(state)
 		`PROC_HALT_STATE:
 			HALT=1;
 		`PROC_IF_STATE_ENTRY:begin
+			EXCEPTION=0;
 			external_address_bus <= ProgCount;
 			read <= 0;
 			write <= 1;
@@ -53,37 +98,46 @@ always @(posedge clock) begin
 			external_address_bus <= ProgCount; /*Remenance from IF*/
 			case(CIR[15:10])
 				6'b100000 : begin
+					/* ADD, ADC, SUB, SBB, CMP , AND, ... */
 					case (CIR[5:3])
 						3'b000 : begin
-							ADD_INST=1;
+							/* Add Immediate to register/memory */
+							in1_sel=2'b00;
+							in2_sel=2'b01;
+							out_sel=2'b01;
+							PARAM2[2:0]=CIR[2:0];
+							PARAM2[5:3]=CIR[2:0];
 							state=`PROC_DE_LOAD_16_PARAM;
 						end
 						default:begin
-							EXCEPTION=1;
-							state=`PROC_EX_STATE_ENTRY;
+							`invalid_instruction
 						end
 					endcase
 				end
 				6'b111111 : begin
+					/* INC */
 					if (CIR[9:9] == 1 ) begin
 						case (CIR[5:3])
 							3'b000 :begin
-								INC_INST=1;
+								/* Increment Register or Memmory */
+								in1_sel=2'b00;
+								in2_sel=2'b01;
+								out_sel=2'b01;
+								PARAM1=1;
+								PARAM2[2:0]=CIR[2:0];
+								PARAM2[5:3]=CIR[2:0];
 								state=`PROC_EX_STATE_ENTRY;
 							end
 							default:begin
-								EXCEPTION=1;
-								state=`PROC_EX_STATE_ENTRY;
+								`invalid_instruction
 							end
 						endcase
 					end else begin
-						EXCEPTION=1;
-						state=`PROC_EX_STATE_ENTRY;
+						`invalid_instruction
 					end
 				end
 				default:begin
-					EXCEPTION=1;
-					state=`PROC_EX_STATE_ENTRY;
+					`invalid_instruction
 				end
 			endcase
 		end
@@ -93,8 +147,9 @@ always @(posedge clock) begin
 			state=`PROC_EX_STATE_ENTRY;
 		end
 		`PROC_EX_STATE_ENTRY:begin
-			EXCEPTION=0;ADD_INST=0;INC_INST=0;
-			state=`PROC_IF_STATE_ENTRY;
+			EXCEPTION=0;
+			exec_unit_execute=0;
+			state=`PROC_EX_STATE_EXIT;
 		end
 	endcase
 end

cpu/registers.v

@@ -0,0 +1,21 @@
+module register_file ( input [2:0]addr1, inout [15:0]data1, input wire read1, input wire write1 ,input [2:0]addr2,output [15:0]data2,input wire read2);
+reg [15:0] registers [7:0];
+assign data2 = !read2 ? registers[0] : 'b1111000011110000 ;
+//assign data2 = !read2 ? registers[addr2]: 'b1111000011110000;
+assign data1 = !read1 ? registers[addr1]: 'hz;
+initial begin 
+	registers['b000]=0;
+	registers['b001]=0;
+	registers['b010]=0;
+	registers['b011]=0;
+	registers['b100]=0;
+	registers['b101]=0;
+	registers['b110]=0;
+	registers['b111]=0; // TODO Don't clear. Remove after we implement the MOV instruction
+end
+always @(negedge write1) begin
+	registers[addr1] = data1;
+	//$display("registers: 0:%04x 1:%04x 2:%04x",registers[0],registers[1],registers[2]);
+	$display("register %d update to %04x (data bus %04x)",addr1,registers[addr1],data1);
+end
+endmodule

cpu/testbench.v

@@ -27,6 +27,7 @@ initial begin
 	#(`CPU_SPEED) 
 	reset = 1;
 	#(`CPU_SPEED*30)
+	//$writememh("register_dump.txt", registers);
 
 	#50 $finish;
 end