#include "uart.h"


int fd = -1;
uart_cfg_t uart_cfg = {
    .baudrate = 115200,
    .dbit = 8,
    .parity = 'N',
    .sbit = 0,
};


static void io_handler(int sig, siginfo_t *info, void *context)
{
    unsigned char buf[50] = {0};
    int ret;
    int n;

    if(SIGRTMIN != sig)
        return;

    /* 判断串口是否有数据可读 */
    if (POLL_IN == info->si_code) {
        ret = read(fd, buf, 50); //一次最多读 50 个字节数据
        printf("[ ");

        for (n = 0; n < ret; n++)
            printf("%hhx ", buf[n]);

        printf("]\n");
    }
}

int uart_Init(void)
{   
    /* 打开串口终端 */
    fd = open(UART_DEV, O_RDWR | O_NOCTTY);
    if (0 > fd) {
        fprintf(stderr, "open error: %s: %s\n", UART_DEV, strerror(errno));
        return -1;
    }

    setuart_cfg(&uart_cfg);

    async_io_init();

    return 0;
}

int setuart_cfg(const uart_cfg_t *cfg)
{
    struct termios new_cfg = {0}; //将 new_cfg 对象清零
    speed_t speed;

    /* 设置为原始模式 */
    cfmakeraw(&new_cfg);

    /* 使能接收 */
    new_cfg.c_cflag |= CREAD;
    
    /* 设置波特率 */
    switch (cfg->baudrate) {
    case 1200: speed = B1200;
        break;
    case 1800: speed = B1800;
        break;
    case 2400: speed = B2400;
        break;
    case 4800: speed = B4800;
        break;
    case 9600: speed = B9600;
        break;
    case 19200: speed = B19200;
        break;
    case 38400: speed = B38400;
        break;
    case 57600: speed = B57600;
        break;
    case 115200: speed = B115200;
        break;
    case 230400: speed = B230400;
        break;
    case 460800: speed = B460800;
        break;
    case 500000: speed = B500000;
        break;
    default: //默认配置为 115200
        speed = B115200;
        printf("default baud rate: 115200\n");
        break;
    }

    if (0 > cfsetspeed(&new_cfg, speed)) {
        fprintf(stderr, "cfsetspeed error: %s\n", strerror(errno));
        return -1;
    }

    /* 设置数据位大小 */
    new_cfg.c_cflag &= ~CSIZE; //将数据位相关的比特位清零
    switch (cfg->dbit) {
    case 5:
        new_cfg.c_cflag |= CS5;
        break;
    case 6:
        new_cfg.c_cflag |= CS6;
        break;
    case 7:
        new_cfg.c_cflag |= CS7;
        break;
    case 8:
        new_cfg.c_cflag |= CS8;
        break;
    default: //默认数据位大小为 8
        new_cfg.c_cflag |= CS8;
        printf("default data bit size: 8\n");
        break;
    }

    /* 设置奇偶校验 */
    switch (cfg->parity) {
    case 'N': //无校验
        new_cfg.c_cflag &= ~PARENB;
        new_cfg.c_iflag &= ~INPCK;
        break;
    case 'O': //奇校验
        new_cfg.c_cflag |= (PARODD | PARENB);
        new_cfg.c_iflag |= INPCK;
        break;
    case 'E': //偶校验
        new_cfg.c_cflag |= PARENB;
        new_cfg.c_cflag &= ~PARODD; /* 清除 PARODD 标志，配置为偶校验 */
        new_cfg.c_iflag |= INPCK;
        break;
    default: //默认配置为无校验
        new_cfg.c_cflag &= ~PARENB;
        new_cfg.c_iflag &= ~INPCK;
        printf("default parity: N\n");
        break;
    }

    /* 设置停止位 */
    switch (cfg->sbit) {
    case 1: //1 个停止位
        new_cfg.c_cflag &= ~CSTOPB;
        break;
    case 2: //2 个停止位
        new_cfg.c_cflag |= CSTOPB;
        break;
    default: //默认配置为 1 个停止位
        new_cfg.c_cflag &= ~CSTOPB;
        printf("default stop bit size: 1\n");
        break;
    }

    /* 将 MIN 和 TIME 设置为 0 */
    new_cfg.c_cc[VTIME] = 0;
    new_cfg.c_cc[VMIN] = 0;

    /* 清空缓冲区 */
    if (0 > tcflush(fd, TCIOFLUSH)) {
        fprintf(stderr, "tcflush error: %s\n", strerror(errno));
        return -1;
    }

    /* 写入配置、使配置生效 */
    if (0 > tcsetattr(fd, TCSANOW, &new_cfg)) {
        fprintf(stderr, "tcsetattr error: %s\n", strerror(errno));
        return -1;
    }

    /* 配置 OK 退出 */
    return 0;
}



void async_io_init(void)
{
    struct sigaction sigatn;
    int flag;

    /* 使能异步 I/O */
    flag = fcntl(fd, F_GETFL); //使能串口的异步 I/O 功能
    flag |= O_ASYNC;
    fcntl(fd, F_SETFL, flag);

    /* 设置异步 I/O 的所有者 */
    fcntl(fd, F_SETOWN, getpid());

    /* 指定实时信号 SIGRTMIN 作为异步 I/O 通知信号 */
    fcntl(fd, F_SETSIG, SIGRTMIN);

    /* 为实时信号 SIGRTMIN 注册信号处理函数 */
    sigatn.sa_sigaction = io_handler; //当串口有数据可读时，会跳转到 io_handler 函数
    sigatn.sa_flags = SA_SIGINFO;
    sigemptyset(&sigatn.sa_mask);
    sigaction(SIGRTMIN, &sigatn, NULL);
}