C..  XINOUT.FTN   BOHDEN K. CMAYLO    DEC 81
C..
C..  ROUTINE TO CONTROL SEQUENTIAL INPUT/OUTPUT
C..
	SUBROUTINE XINOUT(IERR,IUNIT,M,INPUT)
C..
C..	THIS ROUTINE ASSIGNS A FILE TO A FORTRAN UNIT NUMBER
C..
C..	IERR=- IF XINOUT ERROR, + IF SYSTEM ERROR
C..	-1=BAD UNIT NUMBER
C..	-2='IN' OR 'OUT' MISSING
C..	-3=NO '=' OR '?' FOR END OF MESSAGE
C..	-4=ERROR IN INPUT STRING (NO BLANK)
C..	IUNIT = 1-99  (- = NO PRINT RESPONSE)
C..	M = 'IN ' IF EXISTS, 'OUT ' IF DOESNT EXIST, 
C..	     '*' OR 'NO' FOLLOWS 'IN' OR 'OUT' IF NO READ DATA FRON INCR
C..	INPUT=HOLDS NAME OF FILE TO ASSIGN
C..	/AP = APPEND
C..
	BYTE INPUT(80),M(80),II(2),NO(2),IO(3),I0,I9,IA,IAP(3)
	DATA I0,I9,INCR,IPR/'0','9',5,5/
	DATA NO,IAS/'N','O','*'/
	DATA II,IO,IAP/'I','N','O','U','T','/','A','P'/
	KUNIT=IUNIT
	IF(IUNIT.LT.0) KUNIT=-IUNIT
	IF(KUNIT.GE.1.AND.KUNIT.LE.99)GOTO6
	IERR=-1
	RETURN
6	IC=0
C..CHECK FOR IN (OLD)
	IF(M(1).EQ.II(1).AND.M(2).EQ.II(2))IC=3
C..CHECK FOR OUT (NEW)
	IF(M(1).EQ.IO(1).AND.M(2).EQ.IO(2).AND.M(3).EQ.IO(3))IC=4
	IF(IC.GT.0)GOTO1
	IERR=-2
C..
C..	CHECK FOR END OF MESSAGE
C..
1	DO 7 I=IC,80
	IF(M(I).EQ.'='.OR.M(I).EQ.'?')GOTO40
7	CONTINUE
	IERR=-3
	RETURN
C..
C..	CHECK FOR ASTERIC OR 'NO' READ FILE NAME
C..
40	IX=I
	IF(M(IC).NE.IAS.AND.(M(IC).NE.NO(1).OR.M(IC+1).NE.NO(2)))GOTO2
C.. 
C..	ARRANGE IQ FOR INPUT PRINTING
C..
	DO 22 JX=1,30
	IF(INPUT(JX).EQ.0.OR.INPUT(JX).EQ.' ')GOTO23
22	CONTINUE
	IERR=-4
	RETURN
23	IQ=JX-1
	GO TO 24
C..
C..	PRINT PROMPT
C..
2	CONTINUE
	IF(IUNIT.GT.0) IQ=IREADP(M(IC),INPUT)
C..CHECK FOR NO TRAILING BLANKS
35	IF(INPUT(IQ).NE.' ')GOTO36
	IQ=IQ-1
	IF(IQ.GT.0)GOTO35
36	CONTINUE
	INPUT(IQ+1)=0
C..CHECK FOR APPEND (/AP)
	IA=0
	IQX=IQ-2
	DO 33 I=IQX,IQ
	IF(IAP(IA+1).NE.INPUT(I))GOTO34
	INPUT(I)=0
	IA=IA+1
33	CONTINUE
34	CONTINUE
C..
C..	CHECK FOR SY:
C..
24	IQ=IQ+1
	CALL SY('SY:',INPUT,IQ)
	IQ=IQ-1
C..
C..	PRINT OUT RESPONSE (IF WANTED)
C..
	ICC=IC
	IF(M(ICC).EQ.NO(1).AND.M(ICC+1).EQ.NO(2)) ICC=ICC+2
	IF(M(ICC).GE.I0.AND.M(ICC).LE.I9) ICC=ICC+1
	IF(IUNIT.GT.0) WRITE(IPR,5)(M(I),I=ICC,IX),(INPUT(I),I=1,IQ)
5	FORMAT(1X,131A1)
C..
C..	CHECK OUT SYSTEM ERRORS
C..
	CALL ERRSNS
	IF(IC.NE.3.AND.IA.NE.3)
     1 OPEN(UNIT=KUNIT,NAME=INPUT,CARRIAGECONTROL='LIST',TYPE='NEW')
C.. CHECK IF OLD FILE 'IN' OPTION SPECIFIED
	IF(IC.EQ.3.AND.IA.NE.3)
     1 OPEN(UNIT=KUNIT,NAME=INPUT,CARRIAGECONTROL='LIST',TYPE='OLD')
	IF(IA.EQ.3)
     1 OPEN(UNIT=KUNIT,NAME=INPUT,CARRIAGECONTROL='LIST',TYPE='OLD'
     2 ,ACCESS='APPEND')
	CALL ERRSNS(IERR)
	RETURN
C..
C..	EOF ERROR
C..
9	WRITE(IPR,99)
99	FORMAT('0*** ERROR *** FATAL ERROR *** END FILE XINOUT ***')
	CALL EXIT
	END