From 3958f90873f82809b1cde02921a27340caa01bc4 Mon Sep 17 00:00:00 2001
From: Yohan Boujon <yo.boujon@gmail.com>
Date: Tue, 21 Nov 2023 17:40:22 +0100
Subject: [PATCH] Fixed li links that are no longer required. Switch case done
 after step1_lidi. Fixed di_A being faster.

---
 cpu_project/cpu_project.xpr |  2 +-
 src/cpu.vhd                 | 27 +++++++++++++--------------
 2 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/cpu_project/cpu_project.xpr b/cpu_project/cpu_project.xpr
index 964195b..c495338 100644
--- a/cpu_project/cpu_project.xpr
+++ b/cpu_project/cpu_project.xpr
@@ -60,7 +60,7 @@
     <Option Name="IPStaticSourceDir" Val="$PIPUSERFILESDIR/ipstatic"/>
     <Option Name="EnableBDX" Val="FALSE"/>
     <Option Name="DSABoardId" Val="basys3"/>
-    <Option Name="WTXSimLaunchSim" Val="65"/>
+    <Option Name="WTXSimLaunchSim" Val="75"/>
     <Option Name="WTModelSimLaunchSim" Val="0"/>
     <Option Name="WTQuestaLaunchSim" Val="0"/>
     <Option Name="WTIesLaunchSim" Val="0"/>
diff --git a/src/cpu.vhd b/src/cpu.vhd
index ac99aba..03bfddc 100644
--- a/src/cpu.vhd
+++ b/src/cpu.vhd
@@ -67,12 +67,12 @@ ARCHITECTURE cpu_arch OF cpu IS
     );
     END COMPONENT;
 
-    signal li_A, di_A, ex_A, mem_A, re_A  : STD_LOGIC_VECTOR(7 downto 0);
-    signal li_B, ex_B, mem_B, re_B : STD_LOGIC_VECTOR(7 downto 0);
-    signal li_C, di_C, ex_C, mem_C, re_C : STD_LOGIC_VECTOR(7 downto 0);
-    signal li_OP, di_OP, ex_OP, mem_OP, re_OP : STD_LOGIC_VECTOR(3 downto 0);
+    signal ex_A, mem_A, re_A  : STD_LOGIC_VECTOR(7 downto 0);
+    signal ex_B, mem_B, re_B : STD_LOGIC_VECTOR(7 downto 0);
+    signal di_C, ex_C, mem_C, re_C : STD_LOGIC_VECTOR(7 downto 0);
+    signal ex_OP, mem_OP, re_OP : STD_LOGIC_VECTOR(3 downto 0);
     -- Banc de registres
-    signal di_B_in, di_B_out, qA : STD_LOGIC_VECTOR(7 downto 0);
+    signal di_A_in, di_A_out, di_B_in, di_B_out, qA : STD_LOGIC_VECTOR(7 downto 0);
     signal di_OP_in, di_OP_out : STD_LOGIC_VECTOR(3 downto 0);
     signal write_enable : STD_LOGIC;
 
@@ -85,13 +85,13 @@ ARCHITECTURE cpu_arch OF cpu IS
     signal empty_4 : STD_LOGIC_VECTOR(3 downto 0);
     
 begin
-    step1_lidi  : pipeline_step PORT MAP(li_A, li_B, li_C, inst(7 downto 4), clk, di_A, di_B_out, di_C, di_OP_out);
-    step2_diex  : pipeline_step PORT MAP(di_A, di_B_in, di_C, di_OP_in, clk, ex_A, ex_B, ex_C, ex_OP);
+    step1_lidi  : pipeline_step PORT MAP(inst(23 downto 16), inst(15 downto 8), inst(7 downto 0), inst(27 downto 24), clk, di_A_out, di_B_out, di_C, di_OP_out);
+    step2_diex  : pipeline_step PORT MAP(di_A_in, di_B_in, di_C, di_OP_in, clk, ex_A, ex_B, ex_C, ex_OP);
     step3_exmem : pipeline_step PORT MAP(ex_A, ex_B, ex_C, ex_OP, clk, mem_A, mem_B, mem_C, mem_OP);
     step4_memre : pipeline_step PORT MAP(mem_A, mem_B, mem_C, mem_OP, clk, re_A, re_B, re_C, re_OP);
     
     instruction_memory_inst : instruction PORT MAP(PC, inst , clk);
-    memory_register_inst    : reg PORT MAP(li_B(3 downto 0), empty_4, re_A(3 downto 0), re_OP(0), re_B, '1', clk, qA, empty_8);
+    memory_register_inst    : reg PORT MAP(di_B_out(3 downto 0), empty_4, re_A(3 downto 0), re_OP(0), re_B, '1', clk, qA, empty_8);
     
     -- alu_inst                : alu PORT MAP();
     -- data_memory_inst        : data_memory PORT MAP();
@@ -99,22 +99,21 @@ begin
     process(clk)
         begin
             if clk'event and clk='1' then
-                li_OP <= inst(27 downto 24);
-                li_A <= inst(23 downto 16);
-                li_B <= inst(15 downto 8);
-                li_C <= inst(7 downto 0);
                 -- In this case, copy the content of li_A directly to di_A (just the idea)
-                case li_OP is
+                case di_OP_out is
                     -- AFC
                     when X"6" =>
-                        di_B_in <= li_B;
+                        di_B_in <= di_B_out;
+                        di_A_in <= di_A_out;
                         di_OP_in <= "0001";
                 -- In this case, put the content in memory_register_inst and get QA in di_A (just the idea)
                     when X"5" =>
                         di_B_in <= qA;
+                        di_A_in <= di_A_out;
                         di_OP_in <= "0001";
                    when others =>
                         di_B_in <= di_B_out;
+                        di_A_in <= di_A_out;
                         di_OP_in <= di_OP_out;
                 end case;
                 PC <= PC+'1';