From f914d1ec8f3c08caf6ade4df2060ca7642d703cc Mon Sep 17 00:00:00 2001
From: "(Tim) Efthimis Kritikos" <efkf@firemail.cc>
Date: Tue, 16 May 2023 16:29:48 +0100
Subject: [PATCH] Cleaned up processor.v a bit

---
 system/execute.v   |  2 +-
 system/processor.v | 44 +++++++++++++++++++++-----------------------
 2 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/system/execute.v b/system/execute.v
index fe5ae96..ad7a324 100644
--- a/system/execute.v
+++ b/system/execute.v
@@ -79,7 +79,7 @@ always @(posedge valid_input) begin
 	end
 end
 
-always @(negedge set_initial_values) begin
+always @( set_initial_values) begin
 	PARAM1 <= PARAM1_INIT;
 	PARAM2 <= PARAM2_INIT;
 end
diff --git a/system/processor.v b/system/processor.v
index a55bdee..215614a 100644
--- a/system/processor.v
+++ b/system/processor.v
@@ -26,7 +26,6 @@
 `define PROC_STATE_BITS		3
 `define PROC_RESET		3'b000
 `define PROC_DE_STATE_ENTRY	3'b001
-`define PROC_WAIT		3'b010
 `define PROC_HALT		3'b011
 
 //HALT: active high
@@ -215,38 +214,48 @@ always @(posedge clock) begin
 			SIMPLE_MICRO <= 0;
 			proc_state <= `PROC_DE_STATE_ENTRY;
 			owe_set_init <= 0;
+			set_initial_values<=0;
 		end
 		`PROC_DE_STATE_ENTRY:begin
-			if(VALID_INSTRUCTION==1 || SIMPLE_MICRO == 1 ) begin
+			if( VALID_INSTRUCTION==1 || SIMPLE_MICRO == 1 ) begin
 				if(work==0) begin
 					DE_OUTPUT_sampled <= DE_OUTPUT;
 
 					if(SIMPLE_MICRO==0||owe_set_init==1)begin
-						valid_instruction_ack <= !valid_instruction_ack;
-						owe_set_init<=0;
-						set_initial_values<=0;
-
+						/* This runs at the start of the execution of an 8086 instruction */
 						`ifdef DEBUG_PC_ADDRESS
 							$display("Running command at %04x (%08x)",INSTRUCTION_LOCATION,INSTRUCTION);
 						`endif
 						`ifdef CALCULATE_IPC
 							new_instruction <= !new_instruction;
 						`endif
+						valid_instruction_ack <= !valid_instruction_ack;
+						owe_set_init<=0;
+						set_initial_values<= !set_initial_values;
 						ProgCount <= INSTRUCTION_LOCATION+{12'b0,instr_end};
 						INSTRUCTION_BUFFER<=INSTRUCTION[23:0];
 					end
+
 					if ( (ucode_seq_addr==`UCODE_NO_INSTRUCTION) && (ucode_seq_addr_entry!=`UCODE_NO_INSTRUCTION) )begin
-						/*switch to microcode decoding*/
+						/* switch to microcode decoding */
 						ucode_seq_addr <= ucode_seq_addr_entry;
 						SIMPLE_MICRO <= 1;
 						/*keep proc_state the same and rerun decode this time with all the data from the microcode rom*/
 					end else begin
+						/* This runs at the start of each execution cycle, with microcode this is more than once per 8086 instruction */
 						valid_exec_data <= 1;
-						proc_state <= `PROC_WAIT;
+						if( SIMPLE_MICRO == 1 ) begin
+							ucode_seq_addr <= ucode_seq_addr_entry; /*Reused for next address*/
+							if( ucode_seq_addr_entry == `UCODE_NO_INSTRUCTION )begin
+								/*Finished microcode*/
+								SIMPLE_MICRO <= 0;
+							end
+						end
 					end
 				end else begin
-					if( DE_DEPENDS_ON_PREVIOUS == 0)
-						if ( (ucode_seq_addr==`UCODE_NO_INSTRUCTION) && (ucode_seq_addr_entry!=`UCODE_NO_INSTRUCTION) )begin
+					valid_exec_data <= 0;
+					if( DE_DEPENDS_ON_PREVIOUS == 0 )
+						if ( (ucode_seq_addr==`UCODE_NO_INSTRUCTION) && (ucode_seq_addr_entry!=`UCODE_NO_INSTRUCTION) && valid_exec_data==0 )begin
 							/*switch to microcode decoding*/
 							ucode_seq_addr <= ucode_seq_addr_entry;
 							SIMPLE_MICRO <= 1;
@@ -254,19 +263,8 @@ always @(posedge clock) begin
 							/*keep proc_state the same and rerun decode this time with all the data from the microcode rom*/
 						end
 				end
-			end
-		end
-		`PROC_WAIT:begin
-			set_initial_values<=1;
-			valid_exec_data<=0;
-			proc_state <= `PROC_DE_STATE_ENTRY;
-			if( SIMPLE_MICRO == 1 ) begin
-				ucode_seq_addr <= ucode_seq_addr_entry; /*Reused for next address*/
-				if( ucode_seq_addr_entry == `UCODE_NO_INSTRUCTION )begin
-					/*Finished microcode*/
-					SIMPLE_MICRO <= 0;
-				end
-			end
+			end else
+				valid_exec_data <= 0;
 		end
 		`PROC_HALT:begin
 		end