Change single cycle core with delay slot to use separate fetch stage.

When instructions are visualized then it is even more
misleading to keep old instruction in decode phase delay buffer.

The single cycle core with delay slot is upgraded
to the variant with fetch and execute phases.
This way the structure is logical and delay slot
has purpose.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>

2 files changed, 23 insertions, 24 deletions

diff --git a/qtmips_gui/coreview.cpp b/qtmips_gui/coreview.cpp
index 36e9a8d..242c416 100644
--- a/qtmips_gui/coreview.cpp
+++ b/qtmips_gui/coreview.cpp
@@ -268,17 +268,28 @@ QGraphicsSimpleTextItem *CoreViewScene::new_label(const QString &str, qreal x, q
 }
 
 CoreViewSceneSimple::CoreViewSceneSimple(machine::QtMipsMachine *machine) : CoreViewScene(machine) {
-    NEW_I(instr_prim, 230, 60, instruction_fetched);
+    NEW_I(inst_prim, 230, 60, instruction_executed, QColor(255, 173, 230));
     if (machine->config().delay_slot()) {
-        NEW(Latch, delay_slot_latch, 55, 470, machine, 25);
-        NEW_I(instr_delay, 60, 500, instruction_program_counter);
+        NEW(Latch, latch_if_id, 158, 250, machine, 220);
+        NEW_I(inst_fetch,  79, 60, instruction_fetched, QColor(255, 173, 173));
     }
 
     coreview::Connection *con;
     // Fetch stage
-    new_bus(mem_program->connector_instruction(), dc.instr_bus->new_connector(mem_program->connector_instruction()->point()));
-    con = new_bus(ft.junc_pc_4->new_connector(coreview::Connector::AX_Y), dc.add->connector_in_b());
-    con->setAxes({CON_AXIS_Y(270)});
+    if (machine->config().delay_slot()) {
+        struct coreview::Latch::ConnectorPair lp_ft_inst = latch_if_id->new_connector(mem_program->connector_instruction()->y() - latch_if_id->y());
+        new_bus(mem_program->connector_instruction(), lp_ft_inst.in);
+        struct coreview::Latch::ConnectorPair lp_ft_pc = latch_if_id->new_connector(210);
+        new_bus(ft.junc_pc_4->new_connector(coreview::Connector::AX_Y), lp_ft_pc.in);
+        // Decode stage
+        new_bus(lp_ft_inst.out, dc.instr_bus->new_connector(lp_ft_inst.out->point()));
+        con = new_bus(lp_ft_pc.out, dc.add->connector_in_b());
+        con->setAxes({CON_AXIS_Y(270)});
+    } else {
+        new_bus(mem_program->connector_instruction(), dc.instr_bus->new_connector(mem_program->connector_instruction()->point()));
+        con = new_bus(ft.junc_pc_4->new_connector(coreview::Connector::AX_Y), dc.add->connector_in_b());
+        con->setAxes({CON_AXIS_Y(270)});
+    }
     // Decode stage
     coreview::Bus *regs_bus1 = new_bus(regs->connector_read1(), alu->connector_in_a());
     const coreview::Connector *regs_bus_con = dc.cmp->new_connector(-0.5, 1);
@@ -301,22 +312,10 @@ CoreViewSceneSimple::CoreViewSceneSimple(machine::QtMipsMachine *machine) : Core
     con->setAxes({CON_AXIS_Y(678)});
     // WriteBack
     // From decode stage to fetch stage
-    if (machine->config().delay_slot()) {
-        struct coreview::Latch::ConnectorPair lp_addr = delay_slot_latch->new_connector(10);
-        struct coreview::Latch::ConnectorPair lp_branch = delay_slot_latch->new_connector(20);
-        con = new_signal(dc.and_branch->connector_out(), lp_branch.out);
-        con->setAxes({CON_AXIS_Y(370)});
-        new_signal(lp_branch.in, ft.multiplex->connector_ctl());
-        con = new_bus(dc.add->connector_out(), lp_addr.out);
-        con->setAxes({CON_AXIS_Y(360)});
-        con = new_bus(lp_addr.in, ft.multiplex->connector_in(1));
-        con->setAxes({CON_AXIS_Y(10)});
-    } else {
-        con = new_signal(dc.and_branch->connector_out(), ft.multiplex->connector_ctl());
-        con->setAxes({CON_AXIS_Y(370), CON_AXIS_X(490)});
-        con = new_bus(dc.add->connector_out(), ft.multiplex->connector_in(1));
-        con->setAxes({CON_AXIS_Y(360), CON_AXIS_X(480), CON_AXIS_Y(10)});
-    }
+    con = new_signal(dc.and_branch->connector_out(), ft.multiplex->connector_ctl());
+    con->setAxes({CON_AXIS_Y(370), CON_AXIS_X(490)});
+    con = new_bus(dc.add->connector_out(), ft.multiplex->connector_in(1));
+    con->setAxes({CON_AXIS_Y(360), CON_AXIS_X(480), CON_AXIS_Y(10)});
     // From decode to execute stage
     new_signal(dc.ctl_block->new_connector(1, 0.6), ex.mux_imm->connector_ctl());
 	new_signal(dc.ctl_block->new_connector(1, 0.2), alu->connector_ctl());
diff --git a/qtmips_gui/coreview.h b/qtmips_gui/coreview.h
index 0abc870..93c0032 100644
--- a/qtmips_gui/coreview.h
+++ b/qtmips_gui/coreview.h
@@ -130,8 +130,8 @@ public:
     CoreViewSceneSimple(machine::QtMipsMachine *machine);
 
 private:
-    coreview::InstructionView *instr_prim, *instr_delay;
-    coreview::Latch *delay_slot_latch;
+    coreview::InstructionView *inst_prim, *inst_fetch;
+    coreview::Latch *latch_if_id;
 };
 
 class CoreViewScenePipelined : public CoreViewScene {