NAME
dial(), undial() — establish an outgoing terminal line connection
SYNOPSIS
#include <dial.h>
int dial(CALL call);
void undial(int fd);
DESCRIPTION
The
dial()
function returns a file descriptor for a terminal line open for read/write.
The argument to
dial()
is a
CALL
structure (defined in the
<dial.h>
header file).
When finished with the terminal line, the calling program must invoke
undial()
to release the semaphore that has been set
during the allocation of the terminal device.
The definition of
CALL
in the
<dial.h>
header file is:
typedef struct {
struct termio *attr; /* pointer to termio attribute struct */
int baud; /* transmission data rate */
int speed; /* 212A modem: low=300, high=1200 */
char *line; /* device name for out-going line */
char *telno; /* pointer to tel-no digits string */
int modem; /* specify modem control for direct lines */
char *device; /* Will hold the name of the device used
to make a connection */
int dev_len; /* The length of the device used to
make connection */
} CALL;
CALL
elements are as follows:
- speed
Intended only for use with an outgoing dialed call,
in which case its value should be either 300 or 1200
to identify the 113A modem, or the high- or low-speed setting
on the 212A modem.
Note that the 113A modem or the low-speed setting of the 212A modem
transmits at any rate between 0 and 300 bits per second.
However, the high-speed setting of the 212A modem transmits
and receives at 1200 bits per second only.
- baud
Desired transmission baud rate.
For example, one might set
baud
to 110 and
speed
to 300 (or 1200).
However, if
speed
is set to 1200,
baud
must be set to high (1200).
- line
If the desired terminal line is a direct line,
a string pointer to its device name should be placed in the
line
element in the
CALL
structure.
Legal values for such terminal device names are kept in the
Devices
file.
In this case, the value of the
baud
element need not be specified as it will be determined from the
Devices
file.
- telno
A pointer to a character string
representing the telephone number to be dialed.
Such numbers can consist only of symbols described below.
The termination symbol is supplied by the
dial()
function, and should not be included in the
telno
string passed to
dial()
in the
CALL
structure.
Permissible Codes
- 0-9
Dial
0-9
- * or :
Dial
*
- # or ;
Dial
#
- -
4-second delay for second dial tone
- e or <
End of number
- w or =
Wait for secondary dial tone
- f
Flash off-hook for 1 second
- modem
Specifies modem control for direct lines.
Set to non-zero if modem control is required.
- attr
Pointer to a
termio
structure, as defined in the
<termio.h>
header file.
A NULL
value for this pointer element can be passed to the
dial()
function, but if such a structure is included,
the elements specified in it are set for the outgoing terminal line
before the connection is established.
This is often important for certain attributes
such as parity and baud rate.
- device
Holds the device name that establishes the connection.
- dev_len
Length of the device name that is copied into the array device.
RETURN VALUE
On failure, a negative value indicating the reason for
the failure is returned.
Mnemonics for these negative indices as listed here are defined in the
<dial.h>
header file.
INTRPT -1 /* interrupt occurred */
D_HUNG -2 /* dialer hung (no return from write) */
NO_ANS -3 /* no answer within 10 seconds */
ILL_BD -4 /* illegal baud-rate */
A_PROB -5 /* automatic call unit (acu) problem (open() failure) */
L_PROB -6 /* line problem (open() failure) */
NO_Ldv -7 /* can't open LDEVS file */
DV_NT_A -8 /* requested device not available */
DV_NT_K -9 /* requested device not known */
NO_BD_A -10 /* no device available at requested baud */
NO_BD_K -11 /* no device known at requested baud */
WARNINGS
Including the
<dial.h>
header file automatically includes the
<termio.h>
header file.
The above routine uses
<stdio.h>,
which causes unexpected increases in the size of programs
that otherwise do not use standard I/O.
The
dial()
function will modify the values of some of the fields
of the
CALL
structure so if
dial()
is reinvoked, it will reinitialize the values of the
CALL
structure.
Printable version
