Update README and add contrib dir

contrib/tsn/model/cbs.h

@@ -0,0 +1,74 @@
+#ifndef CBS_H
+#define CBS_H
+
+#include "ns3/tsn-transmission-selection-algo.h"
+
+#include "ns3/data-rate.h"
+#include "ns3/traced-callback.h"
+
+namespace ns3
+{
+
+class Cbs: public TsnTransmissionSelectionAlgo
+{
+  public:
+    /**
+     * \brief Get the TypeId
+     *
+     * \return The TypeId for this class
+     */
+    static TypeId GetTypeId();
+
+    /**
+     * \brief Create a Cbs
+     */
+    Cbs();
+
+    /**
+     * Destroy a Cbs
+     *
+     * This is the destructor for the Cbs.
+     */
+    ~Cbs();
+
+    // Delete copy constructor and assignment operator to avoid misuse
+    Cbs& operator=(const Cbs&) = delete;
+    Cbs(const Cbs&) = delete;
+
+
+    bool IsReadyToTransmit() override;
+    void TransmitStart(Ptr<Packet> p, Time txTime) override;
+    void TransmitComplete(Ptr<Packet> p) override;
+    void UpdateTransmissionGate(bool IsOpen) override;
+
+
+    TracedCallback<double> m_creditTrace;
+
+  protected:
+
+  private:
+    void UpdateCredit(bool trigger_cb);
+
+    DataRate m_idleSlope;
+    DataRate m_maxIdleSlope;
+    DataRate m_portTransmitRate;
+    double m_credit;
+    Time m_lastUpdateCreditTime;
+    EventId m_NextCreditUpdate;
+
+
+    enum State
+    {
+        /** Idle with no pkt in the FIFO */
+        IDLE,
+        /** Transmitting a packet */
+        TRANSMITTING,
+        /** Waiting with at least one pkt in the FIFO */
+        WAITING,
+    };
+
+    State m_state;
+};
+
+}
+#endif /* CBS_H */