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esp-protocols/components/esp_modem/include/cxx_include/esp_modem_cmux.hpp
2021-10-04 11:32:55 +02:00

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3.3 KiB
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// 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.
#pragma once
#include "esp_modem_terminal.hpp"
namespace esp_modem {
constexpr size_t MAX_TERMINALS_NUM = 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 itself is not usable as a DTE terminal, only via its instances defined in `CMuxInstance`
*/
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;
size_t instance;
};
/**
* @}
*/
} // namespace esp_modem