编写linux下C语言程序，先将gpio559和gpio560导出，设置gpio559为输出，560为输入，每隔1秒将559输出高，检测gpio560的电平状态

在Linux下编写C语言程序操作GPIO（通用输入/输出），通常需要硬件支持如GPIO设备驱动以及一些系统库，比如`sysfs`接口。这里是一个简化的示例，假设我们使用的是BeagleBone Black（BBB）上的GPIO，并利用`libgpiod`库来操作。请注意，这只是一个基础示例，实际应用可能需要更复杂的错误处理和权限管理。

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/gpio.h>
#include <poll.h>

#define GPIO_559 559
#define GPIO_560 560

void setup_gpio(int gpio, int direction) {
    int fd = open("/sys/class/gpio/export", O_WRONLY);
    if (fd == -1) {
        perror("Failed to export GPIO");
        return;
    }

    char gpios[] = { gpio + '0', '\n' };
    write(fd, gpios, sizeof(gpios));

    close(fd);

    fd = open("/sys/class/gpio/gpio" + gpio, O_RDWR);
    if (fd == -1) {
        perror("Failed to access GPIO");
        return;
    }

    if (direction == GPIO_OUTPUT) {
        write(fd, "out\n", 4); // Set GPIO as output
    } else if (direction == GPIO_INPUT) {
        write(fd, "in\n", 3); // Set GPIO as input
    }

    // Apply the initial direction
    write(fd, &direction + 1, 1); // Use '1' for high and '0' for low

    close(fd);
}

int main() {
    int interval = 1000; // 1 second in milliseconds
    struct pollfd poll_fds[2];
    poll_fds[0].fd = open("/sys/class/gpio/gpio559", O_RDONLY); // GPIO_559
    poll_fds[0].events = POLLIN;

    poll_fds[1].fd = open("/sys/class/gpio/gpio560", O_RDONLY); // GPIO_560
    poll_fds[1].events = POLLIN;

    while (true) {
        int ret = poll(poll_fds, 2, interval * 1000); // Poll for changes every second
        if (ret > 0) {
            char state;
            read(poll_fds[0].fd, &state, 1); // Read from GPIO_559
            if (state == '1') {
                printf("GPIO_559 is high\n");
            } else {
                printf("GPIO_559 is low\n");
            }

            if (poll_fds[1].revents & POLLIN) {
                char level;
                read(poll_fds[1].fd, &level, 1); // Read from GPIO_560
                printf("GPIO_560 level detected: %d\n", level - '0');
            }
        }
    }

    return 0;
}