linux下的串口编程代码1

# include <stdio.h>
# include <stdlib.h>
# include <termio.h>
# include <unistd.h>
# include <fcntl.h>
# include <getopt.h>
# include <time.h>
# include <errno.h>
# include <string.h>

int CommFd, TtyFd;

static void Error(const char *Msg)
{
    fprintf (stderr, "%s\n", Msg);
    fprintf (stderr, "strerror() is %s\n", strerror(errno));
    exit(1);
}
static void Warning(const char *Msg)
{
     fprintf (stderr, "Warning: %s\n", Msg);
}

static int SerialSpeed(const char *SpeedString)
{
    int SpeedNumber = atoi(SpeedString);
#   define TestSpeed(Speed) if (SpeedNumber == Speed) return B##Speed
    TestSpeed(1200);
    TestSpeed(2400);
    TestSpeed(4800);
    TestSpeed(9600);
    TestSpeed(19200);
    TestSpeed(38400);
    TestSpeed(57600);
    TestSpeed(115200);
    TestSpeed(230400);
    Error("Bad speed");
    return -1;
}

static void PrintUsage(void)
{

   fprintf(stderr, "comtest - interactive program of comm port\n");
   fprintf(stderr, "press [ESC] 3 times to quit\n\n");

   fprintf(stderr, "Usage: comtest [-d device] [-t tty] [-s speed] [-7] [-c] [-x] [-o] [-h]\n");
   fprintf(stderr, "         -7 7 bit\n");
   fprintf(stderr, "         -x hex mode\n");
   fprintf(stderr, "         -o output to stdout too\n");
   fprintf(stderr, "         -c stdout output use color\n");
   fprintf(stderr, "         -h print this help\n");
   exit(-1);
}

static inline void WaitFdWriteable(int Fd)
{
    fd_set WriteSetFD;
    FD_ZERO(&WriteSetFD);
    FD_SET(Fd, &WriteSetFD);
    if (select(Fd + 1, NULL, &WriteSetFD, NULL, NULL) < 0) {
   Error(strerror(errno));
    }
 
}

int sendUart(char c)
 {
   WaitFdWriteable(CommFd);
   return write(CommFd, &c, 1);
 }

char recUart()
{
  char c='\0';
  if (FD_ISSET(CommFd, &ReadSetFD))
  {
    if(read(CommFd, &c, 1) == 1) return c;
    else printf("No data to receive.\n");
  }
}

int main(int argc, char **argv)
{
    struct termios TtyAttr;
    struct termios BackupTtyAttr;

    int DeviceSpeed = B115200;
    int TtySpeed = B115200;
    int ByteBits = CS8;
    const char *DeviceName = "/dev/ttyS0";
    const char *TtyName = "/dev/tty";
    int OutputHex = 0;
    int OutputToStdout = 0;
    int UseColor = 0;

    printf("Now we start.\n");
    opterr = 0;
    for (;;) {
        int c = getopt(argc, argv, "d:s:t:7xoch");
        if (c == -1)
            break;
        switch(c) {
        case 'd':
            DeviceName = optarg;
            break;
        case 't':
            TtyName = optarg;
            break;
        case 's':
     if (optarg[0] == 'd') {
  DeviceSpeed = SerialSpeed(optarg + 1);
     } else if (optarg[0] == 't') {
  TtySpeed = SerialSpeed(optarg + 1);
     } else
             TtySpeed = DeviceSpeed = SerialSpeed(optarg);
            break;
 case 'o':
     OutputToStdout = 1;
     break;
 case '7':
     ByteBits = CS7;
     break;
        case 'x':
            OutputHex = 1;
            break;
 case 'c':
     UseColor = 1;
     break;
        case '?':
        case 'h':
        default:
     PrintUsage();
        }
    }
    if (optind != argc)
        PrintUsage();

    CommFd = open(DeviceName, O_RDWR, 0);
    if (CommFd < 0)
 Error("Unable to open device");
    if (fcntl(CommFd, F_SETFL, O_NONBLOCK) < 0)
      Error("Unable set to NONBLOCK mode");

memset(&TtyAttr, 0, sizeof(struct termios));
    TtyAttr.c_iflag = IGNPAR;
    TtyAttr.c_cflag = DeviceSpeed | HUPCL | ByteBits | CREAD | CLOCAL;
    TtyAttr.c_cc[VMIN] = 1;

    if (tcsetattr(CommFd, TCSANOW, &TtyAttr) < 0)
        Warning("Unable to set comm port");

    TtyFd = open(TtyName, O_RDWR | O_NDELAY, 0);
    if (TtyFd < 0)
 Error("Unable to open tty");

    TtyAttr.c_cflag = TtySpeed | HUPCL | ByteBits | CREAD | CLOCAL;
    if (tcgetattr(TtyFd, &BackupTtyAttr) < 0)
 Error("Unable to get tty");

    if (tcsetattr(TtyFd, TCSANOW, &TtyAttr) < 0)
 Error("Unable to set tty");

for (;;) {
 unsigned char Char = 0;
 fd_set ReadSetFD;

 void OutputStdChar(FILE *File) {
     char Buffer[10];
     int Len = sprintf(Buffer, OutputHex ? "%.2X  " : "%c", Char);
     fwrite(Buffer, 1, Len, File);
 }

 FD_ZERO(&ReadSetFD);

 FD_SET(CommFd, &ReadSetFD);
 FD_SET( TtyFd, &ReadSetFD);
# define max(x,y) ( ((x) >= (y)) ? (x) : (y) )
 if (select(max(CommFd, TtyFd) + 1, &ReadSetFD, NULL, NULL, NULL) < 0) {
     Error(strerror(errno));
 }
# undef max

 if (FD_ISSET(CommFd, &ReadSetFD)) {
     while (read(CommFd, &Char, 1) == 1) {

  WaitFdWriteable(TtyFd);
  if (write(TtyFd, &Char, 1) < 0) {
        Error(strerror(errno));
  }
  if (OutputToStdout) {
      if (UseColor)
   fwrite("\x1b[01;34m", 1, 8, stdout);
      OutputStdChar(stdout);
      if (UseColor)
   fwrite("\x1b[00m", 1, 8, stdout);
      fflush(stdout);
  }
     }
 }

 if (FD_ISSET(TtyFd, &ReadSetFD)) {
     while (read(TtyFd, &Char, 1) == 1) {
         static int EscKeyCount = 0;
  WaitFdWriteable(CommFd);
         if (write(CommFd, &Char, 1) < 0) {
        Error(strerror(errno));
  }
  if (OutputToStdout) {
      if (UseColor)
   fwrite("\x1b[01;31m", 1, 8, stderr);
      OutputStdChar(stderr);
      if (UseColor)
   fwrite("\x1b[00m", 1, 8, stderr);
      fflush(stderr);
         }

        if (Char == '\x1b') {
                    EscKeyCount ++;
                    if (EscKeyCount >= 3)
                        goto ExitLabel;
                } else
                    EscKeyCount = 0;
     } 
        }

    }

ExitLabel:
    if (tcsetattr(TtyFd, TCSANOW, &BackupTtyAttr) < 0)
 Error("Unable to set tty");

    return 0;
}