INTEGER FUNCTION SDATA (X)
C
C     ****************************************************************
C
C              KERMIT for the MODCOMP MAXIV operating system
C
C        Compliments of:
C
C                         SETPOINT, Inc.
C                      10245 Brecksville Rd.
C                      Brecksville, Ohio 44141
C
C
C      KERMIT is a copyrighted protocol of Columbia Univ. The authors
C      of this version hereby grant permission to copy this software
C      provided that it is not used for an explicitly commercial
C      purpose and that proper credit be given. SETPOINT, Inc. makes
C      no warranty whatsoever regarding the accuracy of this package
C      and will assume no liability resulting from it's use.
C
C     ****************************************************************
C
C     Abstract:  Send a data packet to the remote Kermit.
C
C     MODIFICATION HISTORY
C
C     BY            DATE     REASON            PROGRAMS AFFECTED
C
C     ****************************************************************
C
C     Author:  Rick Burke           Version: A.0    Date: Sep-86
C
C     Calling Parameters:
C
C     R    X            - Dummy argument required by FORTRAN
C
C     ****************************************************************
C
C     Messages generated by this module :  None
C
C     ****************************************************************
C
C     Subroutines called directly : BUFILL, MOD, RPACK, SPACK
C
C     ****************************************************************
C
C     Files referenced :  None
C
C     ****************************************************************
C
C     Local variable definitions :
C
C     LEN          - Length of received packet
C     NUM          - Number of received packet
C     TNUM         - Expected packet number
C     TV1          - Temporary variable
C
C     ****************************************************************
C
C     Commons referenced :  KER and  KERPAR local commons
C
C     ****************************************************************
C
C     (*$END.DOCUMENT*)
C
C     ****************************************************************
C     *                                                              *
C     *         D I M E N S I O N   S T A T E M E N T S              *
C     *                                                              *
C     ****************************************************************
C
      IMPLICIT INTEGER (A-Z)
C
C     ****************************************************************
C     *                                                              *
C     *         T Y P E   S T A T E M E N T S                        *
C     *                                                              *
C     ****************************************************************
C
C
C     ****************************************************************
C     *                                                              *
C     *         C O M M O N   S T A T E M E N T S                    *
C     *                                                              *
C     ****************************************************************
C
      INCLUDE USL/KERCOM
      INCLUDE USL/KERPMC
C
C     ****************************************************************
C     *                                                              *
C     *         E Q U I V A L E N C E   S T A T E M E N T S          *
C     *                                                              *
C     ****************************************************************
C
C
C     ****************************************************************
C     *                                                              *
C     *         D A T A   S T A T E M E N T S                        *
C     *                                                              *
C     ****************************************************************
C
C
C     ****************************************************************
C
C     Code starts here :
C
C
C----->  Assume some kind of error.
C
      SDATA = BIGA
C
C----->  Retry counter exceeded?
C
      IF (NUMTRY .GT. MAXTRY) RETURN
      NUMTRY = NUMTRY + 1
C
C----->  Send the data packet.
C
      TNUM = N
      TV1 = BIGD
      CALL SPACK (TV1,TNUM,SIZE,PACKET)
C
C----->  If we are in local mode then display the packet
C----->  sequence number.
C
      IF (HOSTON .EQ. NO) WRITE (LOCALO,100) TNUM
C
C----->  Get the reply from the remote.
C
      STATUS = RPACK (LEN,NUM,RECPKT)
C
C----->  The next statements are to make sure that we are not one
C----->  packet ahead of the other Kermit. This will happen if the
C----->  other Kermit sends a NAK (due to a timeout detection)
C----->  before we send the first SINIT packet.
C
      IF (STATUS .EQ.  BIGY .AND.
     >    N      .EQ. NUM+1      ) STATUS = RPACK (LEN,NUM,RECPKT)
      IF (STATUS .NE. BIGN) GO TO 10
C
C----->  We got a NAK.
C
      IF (N .EQ. NUM-1) GO TO 50
      SDATA = STATE
      RETURN
   10 CONTINUE
      IF (STATUS .NE. BIGY) GO TO 40
C
C----->  We got an ACK.
C
      IF (N .EQ. NUM) GO TO 20
C
C----->  But, it was for the last packet.
C
      SDATA = STATE
      RETURN
   20 CONTINUE
      NUMTRY = 0
      N = MOD((N+1),64)
      SIZE = BUFILL (PACKET)
      IF (SIZE .NE. EOF) GO TO 30
      SDATA = BIGZ
      RETURN
   30 CONTINUE
      SDATA = BIGD
      RETURN
   40 CONTINUE
      IF (STATUS .NE. BAD) GO TO 50
C
C----->  We got a checksum error, try again.
C
      SDATA = STATE
      RETURN
   50 CONTINUE
C
C----->  Here we got an unknown packet type or an error occurred.
C
      RETURN
100   FORMAT('+PACKET #',I3,'  ')
      END