实现qnx 通过共享内存获取安卓升级指令，并监测mcu版本状态通过spi进行ota升级并返回升级进度代码加注释

下面是一个简单的QNX程序实现通过共享内存获取安卓升级指令，并监测MCU版本状态通过SPI进行OTA升级并返回升级进度的代码，附加有注释：

#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <hw/spi-master.h>

#define SHARED_MEM_SIZE 4096 // 共享内存大小
#define SPI_DEVICE_PATH "/dev/spi-master1" // SPI设备路径

typedef struct {
    int version; // 版本号
    char upgrade_cmd[256]; // 升级指令
    int upgrade_progress; // 升级进度
} shared_mem_t;

int main(int argc, char *argv[]) {
    int fd; // 共享内存文件描述符
    shared_mem_t *shared_mem; // 共享内存指针

    // 打开共享内存
    if ((fd = shm_open("/upgrade", O_RDWR | O_CREAT, 0666)) < 0) {
        perror("shm_open");
        return EXIT_FAILURE;
    }

    // 设置共享内存大小
    if (ftruncate(fd, SHARED_MEM_SIZE) < 0) {
        perror("ftruncate");
        return EXIT_FAILURE;
    }

    // 映射共享内存
    if ((shared_mem = mmap(NULL, SHARED_MEM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED) {
        perror("mmap");
        return EXIT_FAILURE;
    }

    // 初始化SPI设备
    spi_open_cfg_t spi_cfg = {
        .bus_num = 1,
        .chip_select = 0,
        .mode = SPI_MODE_0,
        .bits_per_word = 8,
        .speed = 1000000 // 1MHz
    };
    int spi_fd = spi_open(SPI_DEVICE_PATH, &spi_cfg);
    if (spi_fd < 0) {
        perror("spi_open");
        return EXIT_FAILURE;
    }

    // 循环读取共享内存中的升级指令并进行OTA升级
    while (1) {
        // 读取共享内存中的升级指令
        int version = shared_mem->version;
        char *upgrade_cmd = shared_mem->upgrade_cmd;
        printf("Received upgrade command: version=%d, cmd=%s\n", version, upgrade_cmd);

        // 检查MCU版本状态
        int mcu_version = 0; // 假设MCU版本为0
        if (version <= mcu_version) {
            printf("MCU version is up to date.\n");
            shared_mem->upgrade_progress = -1; // 升级进度为-1表示MCU已经是最新版本
            continue;
        }

        // 发送OTA升级指令到MCU
        int upgrade_progress = 0;
        int upgrade_cmd_len = strlen(upgrade_cmd);
        int remaining_len = upgrade_cmd_len;
        while (remaining_len > 0) {
            int len = remaining_len > 4096 ? 4096 : remaining_len; // 每次最多发送4096字节
            char buf[4096];
            strncpy(buf, upgrade_cmd + upgrade_cmd_len - remaining_len, len);
            int rc = spi_write(spi_fd, buf, len);
            if (rc < 0) {
                perror("spi_write");
                shared_mem->upgrade_progress = -2; // 升级进度为-2表示发送OTA升级指令失败
                break;
            }
            upgrade_progress += len;
            shared_mem->upgrade_progress = upgrade_progress * 100 / upgrade_cmd_len; // 计算升级进度
            remaining_len -= len;
        }

        // 关闭SPI设备
        spi_close(spi_fd);
    }

    return EXIT_SUCCESS;
}