added examples and p4sim section in the top level readme

Signed-off-by: Vineet1101 <vineetgoel692@gmail.com>

Author: Vineet1101

README.md

@@ -6,6 +6,7 @@
 * [Introduction](#introduction)
 * [Presentation](#presentation)
 * [P4 Documentation](#p4-documentation)
+* [P4Sim] (#p4sim)
 * [Obtaining required software](#obtaining-required-software)
      * [To build the virtual machine](#to-build-the-virtual-machine)
      * [Accessing the VM](#accessing-the-vm)
@@ -83,6 +84,23 @@ All exercises in this repository use the v1model architecture, the documentation
 1. The BMv2 Simple Switch target document accessible [here](https://github.com/p4lang/behavioral-model/blob/master/docs/simple_switch.md) talks mainly about the v1model architecture.
 2. The include file `v1model.p4` has extensive comments and can be accessed [here](https://github.com/p4lang/p4c/blob/master/p4include/v1model.p4).
 
+## P4sim – A Simple P4 Behavioral Simulator
+
+**P4sim** is a lightweight, dependency-free P4 packet-processing simulator designed for learning and experimentation.
+Unlike BMv2 or P4-DPDK, P4sim does **not** emulate a full switch pipeline. Instead, it provides a minimal execution environment that evaluates P4 parser, control, and deparser logic on user-provided packets.
+
+P4sim is intended for:
+
+* Running P4 programs without installing large data plane frameworks
+* Quickly testing parser and control-flow behavior
+* Understanding how P4 programs process packets step-by-step
+
+P4sim is **not** a performance model and does not aim to replicate full-featured switch behavior (such as multitable pipelines, extern objects, or architecture-specific metadata).
+It is mainly a **teaching and debugging tool**.
+
+To learn more or try P4sim examples, see:
+[`P4sim/README.md`](./doc/P4sim/README.md)
+
 ## Obtaining required software
 
 If you are starting this tutorial at one of the proctored tutorial events,

doc/Using_p4sim.md doc/P4sim/README.mddoc/Using_p4sim.md renamed to doc/P4sim/README.md

@@ -2,25 +2,25 @@
 
 ### Index
 
-- ⭐ [Local Deployment (ns-3.39)](#local-deployment-ns339)
+- [Local Deployment (ns-3.39)](#local-deployment-ns339)
 - Virtual Machine as Virtual Env
   - [ns-3 Version 3.x – 3.35](#setup-ns335)
-  - ⭐ [ns-3 Version 3.36 – 3.39](#setup-ns339)
+  -  [ns-3 Version 3.36 – 3.39](#setup-ns339)
 - [Appendix](#appendix)
 
 ## Installation & Usage Guide
 
 It is recommended to use a **virtual machine** with Vagrant to simplify the installation and ensure compatibility. 
 
-## <a name="local-deployment-ns339"></a> Local Deployment (ns-3.39) [⤴️](#index)
+## <a name="local-deployment-ns339"></a> Local Deployment (ns-3.39)
 
 This guide walks you through setting up a local environment to run the P4Sim integrated with `ns-3.39` on Ubuntu 24.04. The full setup includes installing the behavioral model (`bmv2`), setting up SSH for remote access, and building the ns-3 project with P4Sim support. This is tested with `Ubuntu 24.04 LTS Desktop`. 
 
-> ⚠️ Note: The bmv2 and P4 software installation step will take **~3 hours** and consume up to **15GB** of disk space.
+> Note: The bmv2 and P4 software installation step will take **~3 hours** and consume up to **15GB** of disk space.
 
 ---
 
-## 📁 1. Initialize the Working Directory
+## 1. Initialize the Working Directory
 
 Create a workspace and install basic development tools.
 
@@ -33,7 +33,7 @@ sudo apt install git vim cmake
 
 ---
 
-## 🛠️ 2. Install P4 Behavioral Model (bmv2) and Dependencies
+##  2. Install P4 Behavioral Model (bmv2) and Dependencies
 
 > This installs all necessary libraries and tools for P4 development (via the official `p4lang/tutorials` repo).
 
@@ -53,7 +53,7 @@ simple_switch
 
 ---
 
-## 🧪 3. Clone and Build ns-3.39 with P4Simulator
+## 3. Clone and Build ns-3.39 with P4Simulator
 
 ### Step 3.1: Clone ns-3.39
 
@@ -83,7 +83,7 @@ cd ../..
 
 ---
 
-## ▶️ 4. Run an Example
+##  4. Run an Example
 
 You can run a built-in example using:
 
@@ -93,7 +93,7 @@ You can run a built-in example using:
 
 ---
 
-## 🔧 5. Configure P4 Files in Your Simulation
+## 5. Configure P4 Files in Your Simulation
 
 You may need to **manually update file paths** for P4 artifacts in your simulation code.
 
@@ -110,17 +110,17 @@ Make sure these paths match your actual working directory and files.
 
 ---
 
-## ✅ Done!
+## Done!
 
 You now have a working ns-3.39 simulator with P4 integration ready for your experiments.
 
 ---
 
-## 📬 Feedback or Issues?
+## Feedback or Issues?
 
 If you encounter problems or have suggestions, feel free to open an issue or contact the maintainer.
 
-✉️ **Contact:** mingyu.ma@tu-dresden.de
+**Contact:** mingyu.ma@tu-dresden.de
 
 
 
@@ -141,7 +141,7 @@ Notes:
 
 ---
 
-## <a name="setup-ns335"></a>  Setup Instructions for ns-3 version 3.x - 3.35 (Build with `waf`) [⤴️](#index)
+## <a name="setup-ns335"></a>  Setup Instructions for ns-3 version 3.x - 3.35 (Build with `waf`)
 
 This has been tested with ns-3 repo Tag `ns-3.35`.
 
@@ -214,7 +214,7 @@ git apply ./contrib/p4sim/doc/changes.patch
 
 ---
 
-## ⭐  <a name='setup-ns339'></a> Setup Instructions for ns-3 version 3.36 - 3.39 (Build with `Cmake`) [⤴️](#index) 
+##  <a name='setup-ns339'></a> Setup Instructions for ns-3 version 3.36 - 3.39 (Build with `Cmake`)
 
 This has been tested with ns-3 repo Tag `ns-3.39`. Because the virtual machine will build BMv2 and libs with **C++17**, and ns-3 p4simulator using the external inlucde file and libs, therefore the ns-3 also need to build with **C++17**.
 The include file is: `/usr/local/include/bm`, the libs is `/usr/local/lib/libbmall.so`.
@@ -301,7 +301,7 @@ Not been tested yet.
 
 [2] [P4Lang Tutorials repository](https://github.com/p4lang/tutorials/tree/master)
 
-#  <a name='appendix'></a> Appendix [⤴️](#index) 
+#  <a name='appendix'></a> Appendix 
 
 After `Install P4 Behavioral Model (bmv2) and Dependencies`, you should have that: