#include < stdio.h >#include < stdlib.h >#include < errno.h >#include < unistd.h >#include < fcntl.h >#include < string.h >#include < termio.h >#include < time.h >#include < pthread.h >int read_data(int fd, void *buf, int len);int write_data(int fd, void *buf, int len);int setup_port(int fd, int baud, int databits, int parity, int stopbits);void print_usage(char *program_name);pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;pthread_cond_t data_ready = PTHREAD_COND_INITIALIZER;int data_available = 0;void *read_thread(void *arg) {    int fd = *(int *)arg;    char buffer[1024]; // 存储读取的数据    while (1) {        int bytes_read = read_data(fd, buffer, sizeof(buffer));        if (bytes_read > 0) {            printf("Read Thread: Read %d bytes: %s\\n", bytes_read, buffer);        } else {            // 处理读取错误或设备关闭的情况            break;        }    }        pthread_exit(NULL);}void *write_thread(void *arg) {    int fd = *(int *)arg;char input[1024]; // 存储用户输入的数据    while (1) {        printf("Enter data to write (or "q" to quit): ");        fgets(input, sizeof(input), stdin);        if (strcmp(input, "q\\n") == 0 || strcmp(input, "Q\\n") == 0) {            // 用户输入 "q" 或 "Q"，退出循环            break;        }        int len = strlen(input);        int bytes_written = write_data(fd, input, len);        if (bytes_written > 0) {            printf("Write Thread: Wrote %d bytes: %s\\n", bytes_written, input);        }    }        pthread_exit(NULL);}int main(int argc, char *argv[]) //./a.out /dev/ttyS4 115200 8 0 1{    int fd;    int baud;    int len;    int count;    int i;    int databits;    int stopbits;    int parity;    if (argc != 6) {        print_usage(argv[0]);        return 1;    }     baud = atoi(argv[2]);    if ((baud < 0) || (baud > 921600)) {        fprintf(stderr, "Invalid baudrate!\\n");        return 1;    }     databits = atoi(argv[3]);    if ((databits < 5) || (databits > 8)) {        fprintf(stderr, "Invalid databits!\\n");        return 1;    }     parity = atoi(argv[4]);    if ((parity < 0) || (parity > 2)) {        fprintf(stderr, "Invalid parity!\\n");        return 1;    }     stopbits = atoi(argv[5]);    if ((stopbits < 1) || (stopbits > 2)) {        fprintf(stderr, "Invalid stopbits!\\n");        return 1;    }      fd = open(argv[1], O_RDWR, 0);    if (fd < 0) {        fprintf(stderr, "open < %s > error %s\\n", argv[1], strerror(errno));        return 1;    }     if (setup_port(fd, baud, databits, parity, stopbits)) {        fprintf(stderr, "setup_port error %s\\n", strerror(errno));        close(fd);        return 1;    }pthread_t read_tid, write_tid;    int ret;    // 创建读取线程    ret = pthread_create(&read_tid, NULL, read_thread, &fd);    if (ret != 0) {        fprintf(stderr, "Failed to create read thread\\n");        return 1;    }    // 创建写入线程    ret = pthread_create(&write_tid, NULL, write_thread, &fd);    if (ret != 0) {        fprintf(stderr, "Failed to create write thread\\n");        return 1;    }    // 等待读取线程和写入线程结束    pthread_join(read_tid, NULL);    pthread_join(write_tid, NULL);    close(fd);     return 0;}static int baudflag_arr[] = {    B921600, B460800, B230400, B115200, B57600, B38400,    B19200,  B9600,   B4800,   B2400,   B1800,  B1200,    B600,    B300,    B150,    B110,    B75,    B50};static int speed_arr[] = {    921600,  460800,  230400,  115200,  57600,  38400,    19200,   9600,    4800,    2400,    1800,   1200,    600,     300,     150,     110,     75,     50};int speed_to_flag(int speed){    int i;     for (i = 0;  i < sizeof(speed_arr)/sizeof(int);  i++) {        if (speed == speed_arr[i]) {            return baudflag_arr[i];        }    }     fprintf(stderr, "Unsupported baudrate, use 9600 instead!\\n");    return B9600;}static struct termio oterm_attr;int setup_port(int fd, int baud, int databits, int parity, int stopbits){    struct termio term_attr;         if (ioctl(fd, TCGETA, &term_attr) < 0) {        return -1;    }         memcpy(&oterm_attr, &term_attr, sizeof(struct termio));     term_attr.c_iflag &= ~(INLCR | IGNCR | ICRNL | ISTRIP);    term_attr.c_oflag &= ~(OPOST | ONLCR | OCRNL);    term_attr.c_lflag &= ~(ISIG | ECHO | ICANON | NOFLSH);    term_attr.c_cflag &= ~CBAUD;    term_attr.c_cflag |= CREAD | speed_to_flag(baud);         term_attr.c_cflag &= ~(CSIZE);    switch (databits) {        case 5:            term_attr.c_cflag |= CS5;            break;         case 6:            term_attr.c_cflag |= CS6;            break;         case 7:            term_attr.c_cflag |= CS7;            break;         case 8:        default:            term_attr.c_cflag |= CS8;            break;    }         switch (parity) {        case 1:              term_attr.c_cflag |= (PARENB | PARODD);            break;         case 2:              term_attr.c_cflag |= PARENB;            term_attr.c_cflag &= ~(PARODD);            break;         case 0:          default:            term_attr.c_cflag &= ~(PARENB);            break;    }          switch (stopbits) {        case 2:              term_attr.c_cflag |= CSTOPB;            break;         case 1:          default:            term_attr.c_cflag &= ~CSTOPB;            break;    }     term_attr.c_cc[VMIN] = 1;    term_attr.c_cc[VTIME] = 0;     if (ioctl(fd, TCSETAW, &term_attr) < 0) {        return -1;    }     if (ioctl(fd, TCFLSH, 2) < 0) {        return -1;    }     return 0;}  int read_data(int fd, void *buf, int len){    int count;    int ret;     ret = 0;    count = 0;     //while (len > 0) {     ret = read(fd, (char*)buf + count, len);    if (ret < 1) {        fprintf(stderr, "Read error %s\\n", strerror(errno));        //break;    }     count += ret;    len = len - ret;     //}     *((char*)buf + count) = 0;    return count;}  int write_data(int fd, void *buf, int len){    int count;    int ret;     ret = 0;    count = 0;     while (len > 0) {         ret = write(fd, (char*)buf + count, len);        if (ret < 1) {            fprintf(stderr, "Write error %s\\n", strerror(errno));            break;        }         count += ret;        len = len - ret;    }     return count;}void print_usage(char *program_name){    fprintf(stderr,            "*************************************\\n"            "  A Simple Serial Port Test Utility\\n"            "*************************************\\n\\n"            "Usage:\\n  %s < device > < baud > < databits > < parity > < stopbits > \\n"            "       databits: 5, 6, 7, 8\\n"            "       parity: 0(None), 1(Odd), 2(Even)\\n"            "       stopbits: 1, 2\\n"            "Example:\\n  %s /dev/ttyS4 115200 8 0 1\\n\\n",            program_name, program_name           );}

运行效果如下：