在 C++ 中正确地从 C 库初始化 typedef 结构 [英] Initializing typedef struct from C library properly in C++

问题描述

我想在我的 C++ 项目中包含一个库(控制 Raspberry Pi 上的 RGB LED 灯条).导入库工作正常，但我在正确初始化某些结构时遇到了很大的问题.我什至不知道在哪里可以找到正确的语法，我做了很多谷歌搜索，但没有走多远.

I want to include a library in my C++ project (controls RGB LED strips on the Raspberry Pi). Importing the library is working fine but I have quite the issue with properly initializing some structs. I'm pretty lost where to even find the proper syntax, I did a lot of googling but didn't get very far.

我首先想要的是让库附带的示例应用程序运行.请参阅:https://github.com/richardghirst/rpi_ws281x/blob/master/main.c

What I want to at first is getting the sample application going that comes with the library. See: https://github.com/richardghirst/rpi_ws281x/blob/master/main.c

我的主要问题是这个.在C++方式下做的事情我该怎么做?

My main issue is this. How do I do what is done below the C++ way?

ws2811_t ledstring =
{
    .freq = TARGET_FREQ,
    .dmanum = DMA,
    .channel =
    {
        [0] =
        {
            .gpionum = GPIO_PIN,
            .count = LED_COUNT,
            .invert = 0,
            .brightness = 255,
        },
        [1] =
        {
            .gpionum = 0,
            .count = 0,
            .invert = 0,
            .brightness = 0,
        },
    },
};

它的初始化方式是特定于 C 的，并且不会在任何当前的 C++ 标准中编译.请参阅:为什么 C++11 不支持指定初始化程序列为 C99?到目前为止，我只使用过自己的结构体，也从未使用过 typedef，所以我只是对此处定义结构体的方式感到困惑.

The way this is initialized is C specific and doesn't compile in any current C++ standard. See: Why does C++11 not support designated initializer list as C99? So far I only ever used my own structs and also never used typedef, so I'm just confused the way structs are defined here.

上面初始化的结构体就是这样定义的.请参阅:https://github.com/richardghirst/rpi_ws281x/blob/master/ws2811.h

The struct(s) that gets initialized above is defined in this way. See: https://github.com/richardghirst/rpi_ws281x/blob/master/ws2811.h

typedef struct
{
    int gpionum;                          //< GPIO Pin with PWM alternate function
    int invert;                           //< Invert output signal
    int count;                            //< Number of LEDs, 0 if channel is unused
    int brightness;                       //< Brightness value between 0 and 255
    ws2811_led_t *leds;                   //< LED buffers, allocated by driver based on count
} ws2811_channel_t;

typedef struct
{
    struct ws2811_device *device;                //< Private data for driver use
    uint32_t freq;                               //< Required output frequency
    int dmanum;                                  //< DMA number _not_ already in use
    ws2811_channel_t channel[RPI_PWM_CHANNELS];
} ws2811_t;

我尝试的是这样的:

ws2811_led_t matrix[WIDTH][HEIGHT];
ws2811_channel_t channel0 = {GPIO_PIN,LED_COUNT,0,255,*matrix};
ws2811_t ledstring = {nullptr,TARGET_FREQ,DMA,channel0};

当我真正渲染"到 LED 灯条时，它可以编译但导致 malloc 错误:

That compiles but results in a malloc error when I come to actually "render" to the LED strip:

int x, y;

for (x = 0; x < WIDTH; x++)
{
    for (y = 0; y < HEIGHT; y++)
    {
        cout << "LEDs size: " << (y * WIDTH) + x << endl;
        ledstring.channel[0].leds[(y * WIDTH) + x] = matrix[x][y];
    }
}

在循环构造完成后导致此错误消息:

Results in this error message after the loop construct finishes:

malloc(): memory corruption (fast): 0x021acaa8

推荐答案

您应该能够使用以下初始化程序:

You should be able to use use following initializer:

ws2811_t ledstring =
{
    nullptr,
    TARGET_FREQ,
    DMA,
    {
        { GPIO_PIN, 0, LED_COUNT, 255 },
        { 0 }
    }
};

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