lapbConfig()

PROTOTYPE

#include <lapb.h>

int lapbConfig(uint channel, LapbSpec *lapb_spec);

DESCRIPTION

lapbConfig() assigns the LAPB characteristics for the channel specified by channel, which must be in the range from 0 to LAPB_MAX_NUM_CHANNELS - 1 and correspond to a registered HDLC channel. Channel numbers are assigned by hdlcAdd(), which registers the underlying HDLC channel with TargetLAPB. hdlcAdd() is documented in the HDLC driver interface documentation.

lapb_spec points to a LapbSpec structure, defined in “lapb.h” and reproduced below, that defines the channel’s LAPB specifications. For more information on a channel’s LAPB specifications, see the section on using TargetLAPB.

typedef struct
{
  uint  T1;               /* resend timeout (in tenths of seconds) */
  uint  T2;               /* acknowledgment delay (in tenths of seconds) */
  uint  T4;               /* idle channel timeout (tenths of seconds) */
  uint  N2;               /* max retry value */
  uint  window_size;      /* max window size (less than 8/128) */
  ui8   flags;            /* settings */
} LapbSpec;

If successful, lapbConfig() returns 0. Otherwise, it sets errno and returns -1.

ERROR CODES

LAPB_BAD_WIN_SIZE	window_size is either 0, > 7 in normal sequence number mode, > 127 in extend sequence number mode, or >= LAPB_NUM_CHAN_RECV_BUFS if LAPB_USE_SREJ is true.
LAPB_INVALID_CHAN	channel is not in the range from 0 to LAPB_MAX_NUM_CHANNELS -1.
LAPB_T1_ZERO	The T1 value is zero.
LAPB_T2_GE_T1	The T2 value is greater than or equal to the value for T1.
LAPB_T4_LE_T1	The T4 value is less than or equal to the value for T1.
LAPB_UNINITIALIZED	The initialization routine lapbInit() has not been called.

EXAMPLE

  /*-------------------------------------------------------------------*/
  /* Specify the LAPB parameters.                                      */
  /*-------------------------------------------------------------------*/
  lapb_spec.T1 = 30;        /* 3 seconds */
  lapb_spec.T2 = 5;         /* 0.5 seconds */
  lapb_spec.N2 = 10;        /* 10 retries */
  lapb_spec.T4 = 300;       /* 30 seconds */
  lapb_spec.window_size = 20;
  lapb_spec.flags = LAPB_USE_SREJ | LAPB_DTE_ADDR | LAPB_SEQ_MOD_128 |
                    LAPB_OMIT_FRMR;
  rc = lapbConfig(channel, &lapb_spec);