cfgetispeed -- Determine Input Baud Rate

SYNOPSIS

 #include <termios.h>

 speed_t cfgetispeed(const struct termios *termptr);

DESCRIPTION

cfgetispeed returns the input baud rate, which is stored in the termios structure pointed to by termptr. This structure is defined in <termios.h> and contains terminal attribute information.

The tcgetattr function must be used to obtain a copy of the termios structure before you can use the cfgetispeed function to extract the input baud rate from the copy of the structure. The cfsetispeed and tcsetattr functions can then be used to change the input baud rate.

RETURN VALUE

The return value is a defined type, speed_t, which is located in <termios.h>. Each value is associated with an asynchronous line speed as follows:

   Return Value    Baud Rate

   B0              hang up

   B50             50 baud

   B75             75 baud

   B110            110 baud

   B134            134.5 baud

   B150            150 baud

   B200            200 baud

   B300            300 baud

   B600            600 baud

   B1200           1200 baud

   B1800           1800 baud

   B2400           2400 baud

   B4800           4800 baud

   B9600           9600 baud

   B19200          19,200 baud

   B38400          38,400 baud

PORTABILITY

The cfgetispeed function is defined by the POSIX.1 standard and provides portability between operating environments. Note that OpenEdition only supports pseudoterminals and that baud rate does not affect the operation of a pseudoterminal.

EXAMPLE

The following code fragment illustrates the use of tcgetattr and cfgetospeed to determine the speed of stdin.

  #include <sys/types.h>
  #include <termios.h>
  #include <unistd.h>
  #include <stdio.h>

  main()
  {
     struct termios termAttr;
     speed_t baudRate;
     char *inputSpeed = "unknown";

        /* Obtain a copy of the termios structure for stdin. */
     tcgetattr(STDIN_FILENO, &termAttr);
        /* Get the input speed.                              */
     baudRate = cfgetispeed(&termAttr);
        /* Print input speed.                                */
     switch (baudRate) {
        case B0:      inputSpeed = "none"; break;
        case B50:     inputSpeed = "50 baud"; break;
        case B110:    inputSpeed = "110 baud"; break;
        case B134:    inputSpeed = "134 baud"; break;
        case B150:    inputSpeed = "150 baud"; break;
        case B200:    inputSpeed = "200 baud"; break;
        case B300:    inputSpeed = "300 baud"; break;
        case B600:    inputSpeed = "600 baud"; break;
        case B1200:   inputSpeed = "1200 baud"; break;
        case B1800:   inputSpeed = "1800 baud"; break;
        case B2400:   inputSpeed = "2400 baud"; break;
        case B4800:   inputSpeed = "4800 baud"; break;
        case B9600:   inputSpeed = "9600 baud"; break;
        case B19200:  inputSpeed = "19200 baud"; break;
        case B38400:  inputSpeed = "38400 baud"; break;
     }
     printf("Input speed = %sn", inputSpeed);
  }

RELATED FUNCTIONS

cfgetospeed, cfsetispeed, tcgetattr