esp_modem: Moved to component folder

components/esp_modem/include/cxx_include/esp_modem_cmux.hpp

@@ -0,0 +1,112 @@
+// Copyright 2021 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef _ESP_MODEM_CMUX_HPP_
+#define _ESP_MODEM_CMUX_HPP_
+
+#include "esp_modem_terminal.hpp"
+
+namespace esp_modem {
+
+constexpr size_t max_terms = 2;
+/**
+ * @defgroup ESP_MODEM_CMUX ESP_MODEM CMUX class
+ * @brief Definition of CMUX terminal
+ */
+/** @addtogroup ESP_MODEM_CMUX
+* @{
+*/
+
+/**
+ * @brief CMUX state machine
+ */
+enum class cmux_state {
+    INIT,
+    HEADER,
+    PAYLOAD,
+    FOOTER,
+    RECOVER,
+};
+
+/**
+ * @brief CMUX terminal abstraction
+ *
+ * This class inherits from Terminal class, as it is a Terminal, but is also composed of another Terminal,
+ * which is used to communicate with the modem, i.e. the original Terminal which has been multiplexed.
+ *
+ * @note Implementation of CMUX protocol is experimental
+ */
+class CMuxInstance;
+
+/**
+ * @brief CMux class which consumes the original terminal and creates multiple virtual terminals from it.
+ * This class is not usable applicable as a DTE terminal
+ */
+class CMux {
+public:
+    explicit CMux(std::unique_ptr<Terminal> t, std::unique_ptr<uint8_t[]> b, size_t buff_size):
+            term(std::move(t)), buffer_size(buff_size), buffer(std::move(b)), payload_start(nullptr), total_payload_size(0) {}
+    ~CMux() = default;
+    [[nodiscard]] bool init();
+    void set_read_cb(int inst, std::function<bool(uint8_t *data, size_t len)> f);
+
+    int write(int i, uint8_t *data, size_t len);
+private:
+    std::function<bool(uint8_t *data, size_t len)> read_cb[max_terms];
+    void data_available(uint8_t *data, 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;
+    std::unique_ptr<uint8_t[]> buffer;
+    bool on_cmux(uint8_t *data, size_t len);
+    static uint8_t fcs_crc(const uint8_t frame[6]);
+    Lock lock;
+    int instance;
+    int sabm_ack;
+    uint8_t *payload_start;
+    size_t total_payload_size;
+
+};
+
+/**
+ * @brief This represents a specific instance of a CMUX virtual terminal. This class also implements Terminal interface
+ * and as such could be used as a DTE's terminal.
+ */
+class CMuxInstance: public Terminal {
+public:
+    explicit CMuxInstance(std::shared_ptr<CMux> parent, int i): cmux(std::move(parent)), instance(i) {}
+
+    int write(uint8_t *data, size_t len) override { return cmux->write(instance, data, len); }
+    void set_read_cb(std::function<bool(uint8_t *data, size_t len)> f) override { return cmux->set_read_cb(instance, std::move(f)); }
+    int read(uint8_t *data, size_t len) override { return  0; }
+    void start() override { }
+    void stop() override { }
+private:
+    std::shared_ptr<CMux> cmux;
+    int instance;
+};
+
+/**
+ * @}
+ */
+
+} // namespace esp_modem
+
+#endif // _ESP_MODEM_CMUX_HPP_