X.25 SYSTEM VARIABLES AND MACROS

Variables

plcn_wa	This pointer is the programmer's gateway into the level 3 driver. Initialized by open_x25(), plcn_wa is a pointer to an array of structure pointers, each of which represents a work area for a logical channel. Each logical channel defined has a work area allocated, plus the system server work area, pointed to by the first pointer in the array (plcn_wa[0]). See x25user.h for specific information on the work area structures (type LCN_WA).
psys_wa	This is a pointer to the system work area and is equivalent to plcn_wa[0]. It is furnished primarily for simplicity in de-referencing system variables in the system work area (type SYS_WA) (see x25user.h).
sys_error	This system variable supplies the programmer with diagnostic information concerning library functions in the event of a failure. System error codes stored in sys_error are defined in x25_user.h. Note that sys_error is not automatically cleared and is only valid when a failure occurs in a library function.
sys_diag	May contain additional diagnostic information when sys_error is not comprehensive. An example is when a bad value is detected in the configuration file, sys_diag will contain the number of errors detected.
x25tsrint	If this value is non-zero, a TSR driver is located at the specified interrupt.

Macros

AUTOCALL(lcnfd)	True if autocall is enabled.
CLR_CODE(lcnfd)	Returns the last clear code received on the logical channel referenced by lcnfd.
CLR_DIAG(lcnfd)	Returns the last clear diagnostic code on the logical channel referenced by lcnfd.
CPACKET(line)	The number of bytes in the last packet read by the driver on the indicated line. RX_PACKET points to the actual packet.
D_DATA(lcnfd)	Indicates that a data packet with the D-bit set has been received on the logical channel referenced by lcnfd. This flag is cleared by the function snd_rr(). Note that snd_rr() is not called by the driver, but only when the user removes data from the queue via read_data() (or read) or when specifically called by the user. The user may poll this flag before reading data to check for this event. This flag is an indicator only, and does not account for multiple events between polls.
DATA_SIZE(lcnfd)	The maximum allowed size of the data field in a data packet on lcnfd's line. This value is read from the configuration file.
DEF_WDWIN(lcnfd)	The default level 3 incoming window size for all logical channels on lcnfd's line when not negotiated.
DEF_WDWOUT(lcnfd)	The default level 3 outgoing window size for all logical channels on lcnfd's line when not negotiated.
DSIZE_IN(lcnfd)	The current maximum size for an incoming data packet on the logical channel referenced by lcnfd. When negotiated, this macro is the negotiated packet size, otherwise the default value is used.
DSIZE_OUT(lcnfd)	Same as DSIZE_IN(lcnfd) except outgoing.
FS_OK(lcnfd)	This flag is set to 1 if fast select calls are allowed for all logical channels on lcnfd's line. If fast select is forbidden, FS_OK is 0.
INT_STATE(lcnfd)	The current interrupt state of a logical channel. States are defined in x25user.h.
ISX25_TRACE	Returns TRUE when trace debugging is enabled
ISX25_EVTDEBUG	Returns TRUE when event debugging is enabled.
LAST_LCNFD(lcnfd)	The last logical channel file descriptor defined on lcnfd's line.
LCN(lcnfd)	The logical channel number associated with the file descriptor lcnfd.
LINE(lcnfd)	The line number associated with lcnfd.
LINE_FD(line)	The system server channel for the requested line number.
MAX_WINDOW(lcnfd)	The maximum window for any logical channel on lcnfd's line when negotiated. Must be larger than default values. Windows up to 7 are supported. Not used when NEG_WDW is 0.
NEG_PSIZE(lcnfd)	Set to 1 when packet size negotiation is permitted on lcnfd's line. Otherwise 0.
NEG_TPUT(lcnfd)	Set to 1 when throughput negotiation is permitted on lcnfd's line. Otherwise 0.
NEG_WDW(lcnfd)	Set to 1 when window size negotiation is permitted on lcnfd's line. Otherwise 0.
NUM_LCNS(lcnfd)	The number of logical channels defined for lcnfd's line, not including the server channel (LINE_FD(lcnfd)).
PVC(lcnfd)	TRUE if the logical channel on lcnfd is a permanent virtual circuit.
SET_DBIT(lcnfd)	Set the d-bit flag. The function build_packet() checks this flag when building DATA or CALL packets. If the flag is set prior to building these packets, the d-bit will be set in the resulting packet. This flag is cleared upon use by build_packet().
SET_MBIT(lcnfd)	Set the m-bit flag. Like SET_DBIT, the m-bit will be set in resulting data packets if detected by build_packet(). Cleared by build_packet().
SET_QBIT(lcnfd)	Set the q-bit flag. When this flag is set, build_packet() will set the q-bit in DATA and CALL packets. Cleared by build_packet().
STATE(lcnfd)	The CCITT state of the logical channel referenced by lcnfd. States are explained in the ET/PCX.25 X.25 Users Manual.
SYS_FD(lcnfd)	The system server file descriptor for the line associated with lcnfd.
SYS_MOD(lcnfd)	The bit-pattern mask for packet level modulo on the associated line.
WDW_IN(lcnfd)	The current incoming window for the logical channel referenced by lcnfd. Initially set to the value of DEF_WINDOW and modified if negotiation occurs. Only valid in data transfer state (STATE_P4).
WDW_OUT(lcnfd)	The current outgoing window for the logical channel referenced by lcnfd. Initially set to the value of DEF_WINDOW and modified if negotiation occurs. Only valid in data transfer state (STATE_P4).
WR_TMO(lcnfd)	The current timeout (in seconds) for the write_data() function. Write_data() will wait this many seconds for the level 3 window to open before returning an error condition.
X25_OPEN	When set to TRUE, this flag signals the packet handler that the X.25 environment is valid and packets are to be processed.
X25_TRACE(x)	Set to TRUE to enable trace debugging.
X25_EVTDEBUG(x)	Set to TRUE to enable event debugging.