1
extern "C" void app_main(void)
2
{
3
    // ESP_IDF的入口函数是用C编写的
4
    ESP_ERROR_CHECK(esp_event_loop_create_default());
5

6
    // 初始化NVS闪存
7
    esp_err_t ret = nvs_flash_init();
8
    if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
9
        ESP_LOGW(TAG, "Erasing NVS flash to fix corruption");
10
        ESP_ERROR_CHECK(nvs_flash_erase());
11
        ret = nvs_flash_init();
12
    }
13
    ESP_ERROR_CHECK(ret);
14

15
    auto& app = Application::GetInstance();
16
    app.Start();
17
}

1
#ifndef MY_LIBRARY_H
2
#define MY_LIBRARY_H
3

4
#ifdef __cplusplus
5
extern "C" {
6
#endif
7

8
// 这里的函数声明既能被C编译，也能被C++编译
9
void init_hardware(void);
10
void send_data(const uint8_t* data, size_t len);
11
int receive_data(uint8_t* buffer, size_t max_len);
12

13
#ifdef __cplusplus
14
}
15
#endif
16

17
#endif // MY_LIBRARY_H

1
#include "sdkconfig.h"
2
#ifndef CONFIG_IDF_TARGET_ESP32
3

4
#include <esp_err.h>
5

6
#ifdef __cplusplus
7
extern "C" {
8
#endif
9

10
/**
11
 * @brief JPEG解码函数 - 用C实现，供C++调用
12
 */
13
esp_err_t jpeg_to_image(const uint8_t* src, size_t src_len, uint8_t** out,
14
                        size_t* out_len, size_t* width, size_t* height, size_t* stride);
15

16
#ifdef __cplusplus
17
}
18
#endif
19

20
#endif  // CONFIG_IDF_TARGET_ESP32

1
#ifndef CPP_WRAPPER_H
2
#define CPP_WRAPPER_H
3

4
#ifdef __cplusplus
5
extern "C" {
6
#endif
7

8
// C接口 - 底层调用C++实现
9
void cpp_wrapper_init(void);
10
void cpp_wrapper_process(int data);
11
int cpp_wrapper_get_result(void);
12

13
#ifdef __cplusplus
14
}
15
#endif
16

17
// 下面是C++实现
18
#ifdef __cplusplus
19

20
class DataProcessor {
21
public:
22
    void init() { /* 初始化 */ }
23
    void process(int data) { /* 处理数据 */ }
24
    int getResult() { return result_; }
25
private:
26
    int result_ = 0;
27
};
28

29
#endif

1
#include "cpp_wrapper.h"
2

3
// 静态C++对象
4
static DataProcessor* g_processor = nullptr;
5

6
extern "C" {
7

8
void cpp_wrapper_init() {
9
    g_processor = new DataProcessor();
10
    g_processor->init();
11
}
12

13
void cpp_wrapper_process(int data) {
14
    if (g_processor) {
15
        g_processor->process(data);
16
    }
17
}
18

19
int cpp_wrapper_get_result() {
20
    if (g_processor) {
21
        return g_processor->getResult();
22
    }
23
    return 0;
24
}
25

26
} // extern "C"

1
class CppClass {
2
public:
3
    int add(int a, int b) { return a + b; }
4
};
5

6
// 导出C兼容的函数
7
extern "C" {
8
    CppClass* CppClass_create() {
9
        return new CppClass();
10
    }
11

12
    int CppClass_add(CppClass* obj, int a, int b) {
13
        return obj->add(a, b);
14
    }
15

16
    void CppClass_destroy(CppClass* obj) {
17
        delete obj;
18
    }
19
}

1
// 声明C++函数
2
typedef struct CppClass CppClass;
3
extern CppClass* CppClass_create(void);
4
extern int CppClass_add(CppClass*, int, int);
5
extern void CppClass_destroy(CppClass*);
6

7
void use_cpp_in_c(void) {
8
    CppClass* obj = CppClass_create();
9
    int result = CppClass_add(obj, 1, 2);
10
    CppClass_destroy(obj);
11
}

1
set(SOURCES
2
    # C++源文件
3
    "audio/audio_codec.cc"
4
    "application.cc"
5
    "protocols/protocol.cc"
6
    "protocols/mqtt_protocol.cc"
7
    "protocols/websocket_protocol.cc"
8

9
    # C源文件 - 混合在一起编译！
10
    "display/lvgl_display/gif/gifdec.c"
11
    "display/lvgl_display/jpg/jpeg_to_image.c"   # 注意是.c
12
    "display/lvgl_display/jpg/image_to_jpeg.cpp" # 还有一个.cpp
13
)

1
#ifndef BOARD_H
2
#define BOARD_H
3

4
// 1. 前向声明
5
void* create_board();
6

7
// 2. C++类定义（不暴露给C）
8
class AudioCodec;
9
class Display;
10
class Board {
11
private:
12
    Board(const Board&) = delete;
13
    Board& operator=(const Board&) = delete;
14

15
protected:
16
    Board() = default;
17

18
public:
19
    static Board& GetInstance() {
20
        // 3. 调用C工厂函数创建C++对象
21
        static Board* instance = static_cast<Board*>(create_board());
22
        return *instance;
23
    }
24

25
    virtual ~Board() = default;
26
    virtual std::string GetBoardType() = 0;
27
    virtual AudioCodec* GetAudioCodec() = 0;
28
    virtual Display* GetDisplay() = 0;
29
    // ... 其他纯虚函数
30
};
31

32
// 4. 宏定义 - 供具体板级使用
33
#define DECLARE_BOARD(BOARD_CLASS_NAME) \
34
void* create_board() { \
35
    return new BOARD_CLASS_NAME(); \
36
}
37

38
#endif

1
#include "../common/board.h"
2

3
class EspBoxBoard : public Board {
4
public:
5
    EspBoxBoard() : Board() {}
6
    std::string GetBoardType() override { return "esp-box"; }
7
    AudioCodec* GetAudioCodec() override { /* ... */ }
8
    Display* GetDisplay() override { /* ... */ }
9
};
10

11
// 5. 使用宏注册板级
12
DECLARE_BOARD(EspBoxBoard)

1
class AudioService {
2
public:
3
    // 使用std::function作为回调
4
    void SetCallbacks(AudioServiceCallbacks& callbacks);
5

6
private:
7
    AudioServiceCallbacks callbacks_;
8
};
9

10
// 回调结构体 - C风格，方便从C代码调用
11
struct AudioServiceCallbacks {
12
    std::function<void(void)> on_send_queue_available;
13
    std::function<void(const std::string&)> on_wake_word_detected;
14
    std::function<void(bool)> on_vad_change;
15
};

1
AudioServiceCallbacks callbacks;
2
callbacks.on_send_queue_available = [this]() {
3
    xEventGroupSetBits(event_group_, MAIN_EVENT_SEND_AUDIO);
4
};
5
callbacks.on_wake_word_detected = [this](const std::string &wake_word) {
6
    xEventGroupSetBits(event_group_, MAIN_EVENT_WAKE_WORD_DETECTED);
7
};
8
callbacks.on_vad_change = [this](bool speaking) {
9
    xEventGroupSetBits(event_group_, MAIN_EVENT_VAD_CHANGE);
10
};
11
audio_service_.SetCallbacks(callbacks);

1
#include <esp_log.h>       // ESP-IDF C库
2
#include <cJSON.h>          // C库
3
#include <string>           // C++库
4
#include <vector>           // C++库
5
#include <functional>       // C++库
6

7
// 混用完全OK！
8
class Protocol {
9
    void handleMessage(const char* json_str) {
10
        cJSON* root = cJSON_Parse(json_str);  // C库
11

12
        std::string type = cJSON_GetObjectItem(root, "type")->valuestring;  // C++
13

14
        std::vector<uint8_t> data;  // C++容器
15
        // ... 处理逻辑
16
    }
17
};

1
#ifndef MY_DRIVER_H
2
#define MY_DRIVER_H
3

4
#ifdef __cplusplus
5
extern "C" {
6
#endif
7

8
// 硬件初始化（供C和C++使用）
9
int my_driver_init(void);
10
void my_driver_write(uint8_t data);
11
uint8_t my_driver_read(void);
12

13
// 清理资源
14
void my_driver_deinit(void);
15

16
#ifdef __cplusplus
17
}
18
#endif
19

20
// ===== 以下是C++专用的封装 =====
21
#ifdef __cplusplus
22

23
class MyDriver {
24
public:
25
    MyDriver() = default;
26
    ~MyDriver() { deinit(); }
27

28
    bool init() { return my_driver_init() == 0; }
29
    void write(uint8_t data) { my_driver_write(data); }
30
    uint8_t read() { return my_driver_read(); }
31
    void deinit() { my_driver_deinit(); }
32

33
private:
34
    bool initialized_ = false;
35
};
36

37
#endif
38
#endif

1
# C和C++文件混在一起，CMake会自动识别
2
set(SOURCES
3
    "src/driver.c"         # C驱动
4
    "src/driver.cpp"       # C++包装
5
    "src/app.cpp"          # C++应用
6
    "src/main.cpp"         # C++主程序
7
)
8

9
# 如果需要指定C++标准
10
set(CMAKE_CXX_STANDARD 17)
11
set(CMAKE_CXX_STANDARD_REQUIRED ON)