Merge remote-tracking branch 'origin/dev-sid' into bdunahu

15 files changed, 541 insertions, 97 deletions

diff --git a/gui/gui.cc b/gui/gui.cc
index 9f2405d..5a4c779 100644
--- a/gui/gui.cc
+++ b/gui/gui.cc
@@ -1,39 +1,14 @@
 #include "gui.h"
-#include "ui_gui.h"
-#include <QFile>
-#include <QTextStream>
+#include "./ui_gui.h"
 
-Gui::Gui(QWidget *parent)
-    : QWidget(parent)
-    , ui(new Ui::gui)
+GUI::GUI(QWidget *parent)
+    : QMainWindow(parent)
+    , ui(new Ui::GUI)
 {
     ui->setupUi(this);
-    loadTxtFile();
 }
 
-Gui::~Gui()
+GUI::~GUI()
 {
     delete ui;
 }
-
-void Gui::loadTxtFile(){
-    QFile inputFile(":/resources/input.txt");
-    inputFile.open(QIODevice::ReadOnly);
-
-    QTextStream in(&inputFile);
-    QString line = in.readAll();
-    inputFile.close();
-
-    ui->textEdit->setPlainText(line);
-    QTextCursor cursor = ui->textEdit->textCursor();
-    cursor.movePosition(QTextCursor::Start, QTextCursor::MoveAnchor, 1);
-}
-
-void Gui::on_pushButton_clicked()
-{
-    QString searchString = ui->lineEdit->text();
-    ui->textEdit->find(searchString, QTextDocument::FindWholeWords);
-}
-
-
-
diff --git a/gui/gui.h b/gui/gui.h
index 668fafa..1b700cc 100644
--- a/gui/gui.h
+++ b/gui/gui.h
@@ -1,26 +1,23 @@
 #ifndef GUI_H
 #define GUI_H
-#include <QWidget>
 
-namespace Ui
-{
-class gui;
+#include <QMainWindow>
+
+QT_BEGIN_NAMESPACE
+namespace Ui {
+class GUI;
 }
 QT_END_NAMESPACE
 
-class Gui : public QWidget
+class GUI : public QMainWindow
 {
-	Q_OBJECT
-
-  public:
-	Gui(QWidget *parent = nullptr);
-	~Gui();
+    Q_OBJECT
 
-  private slots:
-	void on_pushButton_clicked();
+public:
+    GUI(QWidget *parent = nullptr);
+    ~GUI();
 
-  private:
-	Ui::gui *ui;
-	void loadTxtFile();
+private:
+    Ui::GUI *ui;
 };
 #endif // GUI_H
diff --git a/gui/gui.ui b/gui/gui.ui
index 5f71c91..00bcbd4 100644
--- a/gui/gui.ui
+++ b/gui/gui.ui
@@ -1,55 +1,435 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
- <class>gui</class>
- <widget class="QWidget" name="gui">
+ <class>GUI</class>
+ <widget class="QMainWindow" name="GUI">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>800</width>
-    <height>600</height>
+    <width>1359</width>
+    <height>606</height>
    </rect>
   </property>
   <property name="windowTitle">
-   <string>gui</string>
+   <string>RISC V[ECTOR]</string>
   </property>
-  <widget class="QWidget" name="">
-   <property name="geometry">
-    <rect>
-     <x>60</x>
-     <y>30</y>
-     <width>317</width>
-     <height>232</height>
-    </rect>
-   </property>
-   <layout class="QVBoxLayout" name="verticalLayout">
+  <widget class="QWidget" name="centralwidget">
+   <layout class="QVBoxLayout" name="verticalLayout_14">
     <item>
-     <layout class="QHBoxLayout" name="horizontalLayout">
-      <item>
-       <widget class="QLabel" name="label">
-        <property name="text">
-         <string>keyword</string>
+     <layout class="QGridLayout" name="gridLayout">
+      <item row="1" column="6" rowspan="2">
+       <widget class="Line" name="line_14">
+        <property name="orientation">
+         <enum>Qt::Vertical</enum>
         </property>
        </widget>
       </item>
-      <item>
-       <widget class="QLineEdit" name="lineEdit"/>
+      <item row="1" column="1" rowspan="2">
+       <layout class="QVBoxLayout" name="verticalLayout">
+        <item>
+         <widget class="QLabel" name="label">
+          <property name="font">
+           <font>
+            <bold>true</bold>
+           </font>
+          </property>
+          <property name="text">
+           <string>Instructions</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="Line" name="line">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QTextEdit" name="textEdit"/>
+        </item>
+       </layout>
       </item>
-      <item>
-       <widget class="QPushButton" name="pushButton">
-        <property name="text">
-         <string>find</string>
+      <item row="1" column="3" rowspan="2">
+       <layout class="QVBoxLayout" name="verticalLayout_13">
+        <item>
+         <layout class="QVBoxLayout" name="verticalLayout_3">
+          <item>
+           <widget class="QLabel" name="label_2">
+            <property name="font">
+             <font>
+              <bold>true</bold>
+             </font>
+            </property>
+            <property name="text">
+             <string>Registers</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="Line" name="line_2">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="QTextEdit" name="textEdit_2"/>
+          </item>
+         </layout>
+        </item>
+        <item>
+         <widget class="Line" name="line_13">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <layout class="QHBoxLayout" name="horizontalLayout_5">
+          <item>
+           <layout class="QVBoxLayout" name="verticalLayout_2">
+            <item>
+             <widget class="QLabel" name="label_4">
+              <property name="font">
+               <font>
+                <bold>true</bold>
+               </font>
+              </property>
+              <property name="text">
+               <string>Cache</string>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="Line" name="line_4">
+              <property name="orientation">
+               <enum>Qt::Horizontal</enum>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="QTextEdit" name="textEdit_4"/>
+            </item>
+           </layout>
+          </item>
+          <item>
+           <widget class="Line" name="line_19">
+            <property name="orientation">
+             <enum>Qt::Vertical</enum>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <layout class="QVBoxLayout" name="verticalLayout_4">
+            <item>
+             <widget class="QLabel" name="label_3">
+              <property name="font">
+               <font>
+                <bold>true</bold>
+               </font>
+              </property>
+              <property name="text">
+               <string>DRAM</string>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="Line" name="line_3">
+              <property name="orientation">
+               <enum>Qt::Horizontal</enum>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="QTextEdit" name="textEdit_3"/>
+            </item>
+           </layout>
+          </item>
+         </layout>
+        </item>
+       </layout>
+      </item>
+      <item row="1" column="2" rowspan="2">
+       <widget class="Line" name="line_17">
+        <property name="orientation">
+         <enum>Qt::Vertical</enum>
+        </property>
+       </widget>
+      </item>
+      <item row="0" column="1" colspan="5">
+       <widget class="Line" name="line_10">
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+       </widget>
+      </item>
+      <item row="3" column="1" colspan="5">
+       <widget class="Line" name="line_11">
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+       </widget>
+      </item>
+      <item row="1" column="5" rowspan="2">
+       <layout class="QVBoxLayout" name="verticalLayout_12">
+        <item>
+         <layout class="QVBoxLayout" name="verticalLayout_8">
+          <item>
+           <widget class="QLabel" name="label_7">
+            <property name="font">
+             <font>
+              <bold>true</bold>
+             </font>
+            </property>
+            <property name="text">
+             <string>Upload Files</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="Line" name="line_5">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <layout class="QVBoxLayout" name="verticalLayout_6">
+            <item>
+             <widget class="QPushButton" name="pushButton_5">
+              <property name="text">
+               <string>Upload Instruction File</string>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <layout class="QHBoxLayout" name="horizontalLayout_3">
+              <item>
+               <widget class="QPushButton" name="pushButton_6">
+                <property name="text">
+                 <string>Upload Program State File</string>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+           </layout>
+          </item>
+          <item>
+           <widget class="Line" name="line_7">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+           </widget>
+          </item>
+         </layout>
+        </item>
+        <item>
+         <layout class="QVBoxLayout" name="verticalLayout_9">
+          <item>
+           <widget class="QLabel" name="label_8">
+            <property name="font">
+             <font>
+              <bold>true</bold>
+             </font>
+            </property>
+            <property name="text">
+             <string>Controls</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="Line" name="line_8">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <layout class="QVBoxLayout" name="verticalLayout_5">
+            <item>
+             <layout class="QHBoxLayout" name="horizontalLayout_2">
+              <item>
+               <widget class="QPushButton" name="pushButton_4">
+                <property name="text">
+                 <string>Refresh DRAM</string>
+                </property>
+               </widget>
+              </item>
+              <item>
+               <widget class="QPushButton" name="pushButton_2">
+                <property name="text">
+                 <string>Refresh Cache</string>
+                </property>
+               </widget>
+              </item>
+              <item>
+               <widget class="QPushButton" name="pushButton">
+                <property name="text">
+                 <string>Refresh Registers</string>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+            <item>
+             <layout class="QHBoxLayout" name="horizontalLayout">
+              <item>
+               <widget class="QCheckBox" name="checkBox">
+                <property name="text">
+                 <string>Enable Pipeline</string>
+                </property>
+               </widget>
+              </item>
+              <item>
+               <widget class="QCheckBox" name="checkBox_2">
+                <property name="text">
+                 <string>Enable Cache</string>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+           </layout>
+          </item>
+         </layout>
+        </item>
+        <item>
+         <layout class="QVBoxLayout" name="verticalLayout_10">
+          <item>
+           <widget class="Line" name="line_15">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="QLabel" name="label_9">
+            <property name="font">
+             <font>
+              <bold>true</bold>
+             </font>
+            </property>
+            <property name="text">
+             <string>Run</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="Line" name="line_9">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <layout class="QVBoxLayout" name="verticalLayout_7">
+            <item>
+             <layout class="QHBoxLayout" name="horizontalLayout_4">
+              <item>
+               <widget class="QLineEdit" name="lineEdit">
+                <property name="placeholderText">
+                 <string># Steps</string>
+                </property>
+               </widget>
+              </item>
+              <item>
+               <widget class="QPushButton" name="pushButton_7">
+                <property name="text">
+                 <string>Run Steps</string>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+            <item>
+             <widget class="QPushButton" name="pushButton_8">
+              <property name="text">
+               <string>Step</string>
+              </property>
+             </widget>
+            </item>
+           </layout>
+          </item>
+         </layout>
+        </item>
+        <item>
+         <widget class="Line" name="line_16">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <layout class="QVBoxLayout" name="verticalLayout_11">
+          <item>
+           <widget class="QLabel" name="label_11">
+            <property name="font">
+             <font>
+              <bold>true</bold>
+             </font>
+            </property>
+            <property name="text">
+             <string>Program State</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="Line" name="line_6">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="QLabel" name="label_6">
+            <property name="text">
+             <string>Clock Cycles</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="QPushButton" name="pushButton_3">
+            <property name="text">
+             <string>Save Current Program State</string>
+            </property>
+           </widget>
+          </item>
+         </layout>
+        </item>
+       </layout>
+      </item>
+      <item row="0" column="0" rowspan="3">
+       <widget class="Line" name="line_12">
+        <property name="orientation">
+         <enum>Qt::Vertical</enum>
+        </property>
+       </widget>
+      </item>
+      <item row="1" column="4" rowspan="2">
+       <widget class="Line" name="line_18">
+        <property name="orientation">
+         <enum>Qt::Vertical</enum>
         </property>
        </widget>
       </item>
      </layout>
     </item>
-    <item>
-     <widget class="QTextEdit" name="textEdit"/>
-    </item>
    </layout>
   </widget>
+  <widget class="QMenuBar" name="menubar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>1359</width>
+     <height>26</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QStatusBar" name="statusbar"/>
  </widget>
- <resources/>
+<resources/>
  <connections/>
 </ui>
diff --git a/gui/main.cc b/gui/main.cc
index 8f9d06b..ce47d10 100644
--- a/gui/main.cc
+++ b/gui/main.cc
@@ -80,9 +80,9 @@ int main(int argc, char **argv)
 	} else {
 		global_log->log(INFO, "Starting QT...");
 		QApplication a(argc, argv);
-		Gui w;
-		w.show();
-		a.exec();
+    	GUI w;
+    	w.show();
+    	return a.exec();
 	}
 
 	global_log->log(INFO, "Cleaning up...");
diff --git a/inc/id.h b/inc/id.h
index 3ff5063..ebbe290 100644
--- a/inc/id.h
+++ b/inc/id.h
@@ -64,8 +64,7 @@ class ID : public Stage
 	 * @param the resulting third field, which varies per type.
 	 * @param the resulting mnemonic.
 	 */
-	void get_instr_fields(
-		signed int &s1, signed int &s2, signed int &s3, Mnemonic &m);
+	void get_instr_fields(signed int &s1, signed int &s2, signed int &s3, Mnemonic &m, Type &t);
 	void decode_R_type(signed int &s1, signed int &s2, signed int &s3);
 	void decode_I_type(signed int &s1, signed int &s2, signed int &s3);
 	void decode_J_type(signed int &s1, signed int &s2);
diff --git a/inc/instr.h b/inc/instr.h
index 7fbb42b..d17613d 100644
--- a/inc/instr.h
+++ b/inc/instr.h
@@ -45,6 +45,13 @@ enum Mnemonic {
 	NOP,
 };
 
+enum Type {
+	R,
+	I,
+	J,
+	INV
+};
+
 namespace instr
 {
 // clang-format off
diff --git a/inc/instrDTO.h b/inc/instrDTO.h
index 77a223e..8249122 100644
--- a/inc/instrDTO.h
+++ b/inc/instrDTO.h
@@ -43,6 +43,10 @@ class InstrDTO
 	 * @return the mnemonic of the instruction
 	 */
 	Mnemonic get_mnemonic();
+	/**
+	 * @return the type of the instruction
+	 */
+	Type get_type();
 
 	/**
 	 * @param set hist key
@@ -68,6 +72,11 @@ class InstrDTO
 	 * @param the mnemonic of the instruction
 	 */
 	void set_mnemonic(Mnemonic);
+	
+	/**
+	 * @param the type of the instruction
+	 */
+	void set_type(Type);
 
   private:
 	/**
@@ -91,6 +100,11 @@ class InstrDTO
 	 * The mnemonic of the operation.
 	 */
 	Mnemonic mnemonic;
+
+	/**
+	 * Type of the instruction
+	 */
+	Type type;
 };
 
 #endif /* INSTRDTO_H_INCLUDED */
diff --git a/inc/stage.h b/inc/stage.h
index 84d2a7b..03048b0 100644
--- a/inc/stage.h
+++ b/inc/stage.h
@@ -30,11 +30,9 @@ class Stage
 	 * Advances this stage by a single clock cycle.
 	 * A boilerplate version is provided in stage.cc.
 	 *
-	 * @param a DTO object containing the next instruction to be processed.
 	 * @param a response, indicating whether or not the parent pipe stage is
 	 * ready to accept a new instruction object next cycle.
-	 * @return a response, indicating whether this pipeline stage is stalling,
-	 * busy, or done.
+	 * @return a DTO object containing the next instruction to be processed.
 	 *
 	 * Must set the status to STALLED when an operation completes.
 	 */
@@ -55,6 +53,11 @@ class Stage
 	 */
 	void set_pc(unsigned int pc);
 
+	/**
+	 * Squashes the pipeline.
+	 */
+	void squash();
+
   protected:
 	/**
 	 * The function expected to do the majority of the work.
diff --git a/src/sim/controller.cc b/src/sim/controller.cc
index 06591af..89ff4e7 100644
--- a/src/sim/controller.cc
+++ b/src/sim/controller.cc
@@ -31,10 +31,11 @@ int Controller::get_pc() { return this->pc; }
 InstrDTO *Controller::advance(Response p)
 {
 	InstrDTO *r;
-
 	r = this->next->advance(p);
 	++this->clock_cycle;
 	return r;
 }
 
-void Controller::advance_helper() {}
+void Controller::advance_helper() {
+	// TODO: check halt condition and call UI to refresh
+}
diff --git a/src/sim/ex.cc b/src/sim/ex.cc
index 83c72d5..3d95917 100644
--- a/src/sim/ex.cc
+++ b/src/sim/ex.cc
@@ -282,28 +282,28 @@ EX::EX(Stage *stage) : Stage(stage)
 		INIT_INSTRUCTION(
 			BEQ,
 			{
-				s1 = this->pc + s2;
+				(this->get_condition(EQ)) ? s1 = this->pc + s2 : s1 = this->pc;
 				(void)s3;
 			}),
 
 		INIT_INSTRUCTION(
 			BGT,
 			{
-				s1 = this->pc + s2;
+				(this->get_condition(GT)) ? s1 = this->pc + s2 : s1 = this->pc;
 				(void)s3;
 			}),
 
 		INIT_INSTRUCTION(
 			BUF,
 			{
-				s1 = this->pc + s2;
+				(this->get_condition(UF)) ? s1 = this->pc + s2 : s1 = this->pc;
 				(void)s3;
 			}),
 
 		INIT_INSTRUCTION(
 			BOF,
 			{
-				s1 = this->pc + s2;
+				(this->get_condition(OF)) ? s1 = this->pc + s2 : s1 = this->pc;
 				(void)s3;
 			}),
 
diff --git a/src/sim/id.cc b/src/sim/id.cc
index edf74e2..0b75b64 100644
--- a/src/sim/id.cc
+++ b/src/sim/id.cc
@@ -46,38 +46,43 @@ void ID::advance_helper()
 {
 	signed int s1, s2, s3;
 	Mnemonic m;
+	Type t;
 
 	// it may be good to ensure we are not doing
 	// work that has already been done
-	if (this->curr_instr) {
+	if (this->curr_instr && this->curr_instr->get_mnemonic() == NONE) {
 		s1 = curr_instr->get_instr_bits();
-		get_instr_fields(s1, s2, s3, m);
+		get_instr_fields(s1, s2, s3, m ,t);
 		if (this->status == OK) {
 			curr_instr->set_s1(s1);
 			curr_instr->set_s2(s2);
 			curr_instr->set_s3(s3);
 			curr_instr->set_mnemonic(m);
+			curr_instr->set_type(t);
 		}
 	}
 }
 
-void ID::get_instr_fields(
-	signed int &s1, signed int &s2, signed int &s3, Mnemonic &m)
+void ID::get_instr_fields(signed int &s1, signed int &s2, signed int &s3, Mnemonic &m, Type &t)
 {
 	unsigned int type;
 	this->split_instr(s1, type, m);
 
 	switch (type) {
 	case 0b00:
+		t = R;
 		this->decode_R_type(s1, s2, s3);
 		break;
 	case 0b01:
+		t = I;
 		this->decode_I_type(s1, s2, s3);
 		break;
 	case 0b10:
+		t = J;
 		this->decode_J_type(s1, s2);
 		break;
 	case 0b11:
+		t = INV;
 		this->status = OK;
 	}
 }
diff --git a/src/sim/instrDTO.cc b/src/sim/instrDTO.cc
index 5a7fe3b..b33c26b 100644
--- a/src/sim/instrDTO.cc
+++ b/src/sim/instrDTO.cc
@@ -7,7 +7,8 @@ InstrDTO::InstrDTO()
 	this->s1 = 0;
 	this->s2 = 0;
 	this->s3 = 0;
-	this->mnemonic = NOP;
+	this->mnemonic = NONE;
+	this->type = INV;
 }
 
 int InstrDTO::get_time_of(Accessor a) { return this->hist[a]; }
@@ -22,6 +23,8 @@ signed int InstrDTO::get_s3() { return this->s3; }
 
 Mnemonic InstrDTO::get_mnemonic() { return this->mnemonic; }
 
+Type InstrDTO::get_type() { return this->type; }
+
 void InstrDTO::set_time_of(Accessor a, int i) { this->hist[a] = i; }
 
 void InstrDTO::set_instr_bits(signed int instr) { this->instr_bits = instr; }
@@ -33,3 +36,5 @@ void InstrDTO::set_s2(signed int s) { this->s2 = s; }
 void InstrDTO::set_s3(signed int s) { this->s3 = s; }
 
 void InstrDTO::set_mnemonic(Mnemonic m) { this->mnemonic = m; }
+
+void InstrDTO::set_type(Type t) { this->type = t; }
diff --git a/src/sim/mm.cc b/src/sim/mm.cc
index 2b73207..cd85056 100644
--- a/src/sim/mm.cc
+++ b/src/sim/mm.cc
@@ -6,4 +6,24 @@
 
 MM::MM(Stage *stage) : Stage(stage) { this->id = MEM; } 
 
-void MM::advance_helper() {}
+void MM::advance_helper() {
+	Response r;
+	signed int data;
+	if(this->curr_instr){
+		if (this->curr_instr->get_mnemonic() == LOAD) {
+			r = this->storage->read_word(this->id, this->curr_instr->get_s1(), data);
+			if(r == OK){
+				this->status = OK;
+				this->curr_instr->set_s2(data);
+			}
+		} else if (this->curr_instr->get_mnemonic() == STORE) {
+			r = this->storage->write_word(this->id, this->curr_instr->get_s2(), this->curr_instr->get_s1());
+			if(r == OK){
+				this->status = OK;
+			}
+		} else {
+			// Mem has no work so just forward the instruction to WB
+			this->status = OK;
+		}
+	} 
+}
diff --git a/src/sim/stage.cc b/src/sim/stage.cc
index 11eb822..0f13d65 100644
--- a/src/sim/stage.cc
+++ b/src/sim/stage.cc
@@ -36,7 +36,7 @@ InstrDTO *Stage::advance(Response p)
 
 	if (this->curr_instr && this->status != OK)
 		this->advance_helper();
-	if (this->curr_instr && p == OK) {
+	if (this->status == OK && p == OK && this->curr_instr) {
 		// mutual consent
 		this->curr_instr->set_time_of(this->id, this->clock_cycle);
 		r = new InstrDTO(*this->curr_instr);
@@ -79,3 +79,11 @@ bool Stage::is_checked_out(signed int r)
 	return std::find(this->checked_out.begin(), this->checked_out.end(), r) !=
 		   this->checked_out.end();
 }
+
+void Stage::squash(){
+	this->curr_instr->set_mnemonic(NOP);
+	this->status = OK;
+	if(this->next){
+		this->next->squash();
+	}
+}
diff --git a/src/sim/wb.cc b/src/sim/wb.cc
index 9337aa0..ac47f25 100644
--- a/src/sim/wb.cc
+++ b/src/sim/wb.cc
@@ -6,4 +6,34 @@
 
 WB::WB(Stage *stage) : Stage(stage) { this->id = WRITE; }
 
-void WB::advance_helper() {}
+void WB::advance_helper() {
+    if(this -> curr_instr) {
+        if(this->curr_instr->get_type() == R || this->curr_instr->get_type() == I){ 
+            if(this->checked_out.size() > 0) {
+                signed int reg = this->checked_out.front();
+                this->checked_out.pop_front();
+                if(reg >= GPR_NUM){
+                    // TODO: handle vector instructions
+                } else {
+                    if(this->curr_instr->get_mnemonic() != STORE && this->curr_instr->get_mnemonic() != STOREV){
+                        this->gprs[reg] = this->curr_instr->get_s1();
+                    }
+                }
+            }
+        } else if (this->curr_instr->get_type() == J) {
+            // TODO:handle push pop
+            // branch taken
+            if(this->pc != this->curr_instr->get_s1()) {
+                if(this->curr_instr->get_mnemonic() == JAL){
+                    // set link register to next instruction
+                    this->gprs[1] = this->pc + 1;
+                }
+                this->pc = this->curr_instr->get_s1();  
+                //clear pending registers and squash pipeline
+                this->checked_out = {};
+                this->next->squash();
+            }
+        }
+    }
+    this->status = OK;
+}