Implement perfect forwarding for command lib

esp_modem/include/cxx_include/esp_modem_cmux.hpp

@@ -0,0 +1,45 @@
+//
+// Created by david on 3/8/21.
+//
+
+#ifndef SIMPLE_CXX_CLIENT_ESP_MODEM_CMUX_HPP
+#define SIMPLE_CXX_CLIENT_ESP_MODEM_CMUX_HPP
+
+enum class cmux_state {
+    INIT,
+    HEADER,
+    PAYLOAD,
+    FOOTER,
+    RECOVER,
+};
+
+class CMUXedTerminal: public Terminal {
+public:
+    explicit CMUXedTerminal(std::unique_ptr<Terminal> t, std::unique_ptr<uint8_t[]> b, size_t buff_size):
+            term(std::move(t)), buffer(std::move(b)) {}
+    ~CMUXedTerminal() override = default;
+    void setup_cmux();
+    void set_data_cb(std::function<bool(size_t len)> f) override {}
+    int write(uint8_t *data, size_t len) override;
+    int read(uint8_t *data, size_t len)  override { return term->read(data, len); }
+    void start() override;
+    void stop() override {}
+private:
+    static bool process_cmux_recv(size_t len);
+    void send_sabm(size_t i);
+    std::unique_ptr<Terminal> term;
+    cmux_state state;
+    uint8_t dlci;
+    uint8_t type;
+    size_t payload_len;
+    uint8_t frame_header[6];
+    size_t frame_header_offset;
+    size_t buffer_size;
+    size_t consumed;
+    std::unique_ptr<uint8_t[]> buffer;
+    bool on_cmux(size_t len);
+
+};
+
+
+#endif //SIMPLE_CXX_CLIENT_ESP_MODEM_CMUX_HPP