利用c语言GEC210开发板Linux系统的/picture目录下，有若干文件 利用Linux系统目录操作相关知识，编程获取/picture目录下所有后缀为bmp、jpg、jpeg的图片文件名 这些图片的宽、高事先未知，需要编程获取 每隔500毫秒，清白屏，显示下一幅图片，无论图片是否超出LCD屏幕大小，都从屏幕左上角（0,0）处显示图片全部或局部 能够循环显示这些图片

以下是一个参考代码，可以实现上述功能：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>

#define FB_DEVICE "/dev/fb0"
#define FB_SIZE (800*480*4)

typedef struct {
    unsigned short type;
    unsigned int size;
    unsigned short reserved1;
    unsigned short reserved2;
    unsigned int offset;
    unsigned int header_size;
    unsigned int width;
    unsigned int height;
    unsigned short planes;
    unsigned short bit_count;
    unsigned int compression;
    unsigned int image_size;
    unsigned int x_px_per_meter;
    unsigned int y_px_per_meter;
    unsigned int colors_used;
    unsigned int colors_important;
} __attribute__((packed)) BMP_HEADER;

int main(int argc, char *argv[]) {
    // 打开帧缓存设备
    int fb_fd = open(FB_DEVICE, O_RDWR);
    if (fb_fd < 0) {
        perror("open framebuffer device");
        exit(EXIT_FAILURE);
    }

    // 映射帧缓存内存
    void *fb = mmap(NULL, FB_SIZE, PROT_WRITE, MAP_SHARED, fb_fd, 0);
    if (fb == MAP_FAILED) {
        perror("mmap framebuffer");
        close(fb_fd);
        exit(EXIT_FAILURE);
    }

    // 获取/picture目录下的所有bmp、jpg、jpeg文件
    DIR *dir = opendir("/picture");
    if (dir == NULL) {
        perror("open directory");
        munmap(fb, FB_SIZE);
        close(fb_fd);
        exit(EXIT_FAILURE);
    }

    struct dirent *entry;
    char *filename;
    while ((entry = readdir(dir)) != NULL) {
        filename = entry->d_name;
        int len = strlen(filename);
        if (len > 4 && strcmp(filename+len-4, ".bmp") == 0
            || len > 4 && strcmp(filename+len-4, ".jpg") == 0
            || len > 5 && strcmp(filename+len-5, ".jpeg") == 0) {
            // 打开图片文件
            char filepath[128];
            sprintf(filepath, "/picture/%s", filename);
            int fd = open(filepath, O_RDONLY);
            if (fd < 0) {
                perror("open image file");
                continue;
            }

            // 读取BMP文件头信息，获取图片宽、高
            BMP_HEADER header;
            read(fd, &header, sizeof(header));
            int width = header.width;
            int height = header.height;

            // 映射图片内存
            void *image = mmap(NULL, width*height*3, PROT_READ, MAP_SHARED, fd, 0);
            if (image == MAP_FAILED) {
                perror("mmap image");
                close(fd);
                continue;
            }

            // 清屏
            memset(fb, 0, FB_SIZE);

            // 显示图片
            int x, y;
            for (y = 0; y < height; y++) {
                for (x = 0; x < width; x++) {
                    unsigned char *pixel = (unsigned char *)image + (y*width + x)*3;
                    // 将BGR颜色值转换为ARGB格式
                    unsigned int color = (pixel[0]<<16) | (pixel[1]<<8) | pixel[2];
                    color |= 0xff000000;
                    // 在屏幕上显示像素点
                    *(unsigned int *)(fb + ((y+90)*800 + x+140)*4) = color;
                }
            }

            // 解除图片内存映射
            munmap(image, width*height*3);
            close(fd);

            // 等待500毫秒
            usleep(500000);
        }
    }

    // 关闭目录和帧缓存设备，解除内存映射
    closedir(dir);
    munmap(fb, FB_SIZE);
    close(fb_fd);

    return 0;
}

注意，这是一个简单的示例代码，可能需要根据具体的需求进行修改。另外，该代码假设LCD屏幕分辨率为800x480，图片文件的宽度和高度都不超过这个范围。如果实际情况不同，需要根据需要进行修改。