对结构的错误分配

Question

我有这样的结构：

typedef struct ws2811_channel_t
{
    int gpionum;                                 //< GPIO Pin with PWM alternate function, 0 if unused
    int invert;                                  //< Invert output signal
    int count;                                   //< Number of LEDs, 0 if channel is unused
    int strip_type;                              //< Strip color layout -- one of WS2811_STRIP_xxx constants
    ws2811_led_t *leds;                          //< LED buffers, allocated by driver based on count
    uint8_t brightness;                          //< Brightness value between 0 and 255
    uint8_t wshift;                              //< White shift value
    uint8_t rshift;                              //< Red shift value
    uint8_t gshift;                              //< Green shift value
    uint8_t bshift;                              //< Blue shift value
    uint8_t *gamma;                              //< Gamma correction table
} ws2811_channel_t;

typedef struct ws2811_t
{
    uint64_t render_wait_time;                   //< time in µs before the next render can run
    struct ws2811_device *device;                //< Private data for driver use
    const rpi_hw_t *rpi_hw;                      //< RPI Hardware Information
    uint32_t freq;                               //< Required output frequency
    int dmanum;                                  //< DMA number _not_ already in use
    ws2811_channel_t channel[RPI_PWM_CHANNELS];
} ws2811_t;

还有我的工作示例：

ws2811_channel_t channel = {
        .gpionum = LED_PIN,
        .invert = LED_INVERT,
        .count = LED_COUNT,
        .strip_type = WS2811_STRIP_RGB,
        .brightness = LED_BRIGHTNESS,

    };
    ws2811_t test = {
        .freq = LED_FREQ_HZ,
        .dmanum = LED_DMA,
        channel,
    };
    LOG_INFO("LEDController: Init - " << ws2811_get_return_t_str(ws2811_init(&test)));
    for (int i = 0; i < LED_COUNT; i++)
    {
        test.channel[0].leds[i] = (0 << 16) | (0 << 8) | 0;
    
    }
    ws2811_render(&test);

我想在课堂上正确分配私有财产，所以当我这样声明时：

ws2811_channel_t channel;
channel.gpionum = LED_PIN;
channel.invert = LED_INVERT;
channel.count = LED_COUNT;
channel.strip_type = WS2811_STRIP_RGB;
channel.brightness = LED_BRIGHTNESS;
ws2811_t test;
test.freq = LED_FREQ_HZ;
test.dmanum = LED_DMA;
test.channel[0] = channel;

    LOG_INFO("LEDController: Init - " << ws2811_get_return_t_str(ws2811_init(&test)));
    for (int i = 0; i < LED_COUNT; i++)
    {
        test.channel[0].leds[i] = (0 << 16) | (0 << 8) | 0;
    
    }
ws2811_render(&test);

ws2811_render(&test); 挂起并冻结，在某些时候我得到了指向该方法的错误。 我假设这是因为它以某种方式有错误的分配。但为什么呢？

渲染的定义是

ws2811_return_t  ws2811_render(ws2811_t *ws2811)

从这里：https://github.com/jgarff/rpi_ws281x/blob/master/ws2811.c#L1138

我做错了什么？

Answer 1

在您的第二个示例中，尝试 ws2811_channel_t channel{}; 和 ws2811_t test{}; - 例如添加{}。

如果你这样做，那么你将零初始化所有成员。您的第一个（工作）版本和第二个（损坏的）版本之间的主要区别在于，第一个版本会将 gamma 之类的东西归零，而第二个版本不会。添加{} 将在覆盖所需项目之前将所有内容归零。

如果您执行type a = {...}，那么... 中的任何内容以及未 提及或编入索引的内容都将归零。如果你这样做type b; b.field=value;，这里没有任何东西可以将任何未初始化的字段归零。