.TITLE	ITEM_LIST

;;
;	SUBROUTINE ITEM_LIST( array , code1 , buf1 [, rlen1] , ... ,
;
;+						   coden , bufn [, rlenn])
;
;
;	Builds a list of 'item descriptors' as required by several VAX/VMS
;	System Services as their 'ITMLST' argument.   The list is built in
;	the ARRAY argument,  which must be an INTEGER*4 array large enough
;	to hold the list (three elements for each item code, plus one ele-
;	ment as a terminator).
;
;	The CODEi arguments are the item codes for the items to be return-
;	ed by the System Service. For each item code, a BUFi argument must
;	be supplied.  If the corresponding item code will cause an address
;	or a 'value' (integer)  to be returned,  BUFi must be an INTEGER*4
;	variable and the corresponding RLENi  argument must not be present
;	(not even as  a null argument).   If the item code  will  return a
;	'string', BUFi must be a CHARACTER variable, and RLENi must either
;	be a null argument or an INTEGER*4 variable.  If present, the act-
;	ual length of the string will be returned in RLENi.  For example:
;
;	  CALL ITEM_LIST(ITMLST,JPI$_PRI,PRIORITY,JPI$_USERNAME,USERN,,
;	1					   JPI$_PRCNAM,PRCNAM,LEN)
;
;	The JPI$_PRI item code returns an integer value,  so PRIORITY must
;	be an INTEGER*4 variable.   JPI$_USERNAME and JPI$_PRCNAM both re-
;	turn strings, so USERN and PRCNAM must be CHARACTER variables, and
;	the RLENi arguments must be used  (a null argument is used for the
;	USERNAME item and INTEGER*4 variable LEN for the PRCNAM item).
;
;	ITEM_LIST will signal  SS$_INSFARG  if it determines that you have
;	not passed a correct argument list.   It cannot,  however, do this
;	in all cases,  so a bad argument list may not  be discovered until
;	you call the System Service and get an abort or incorrect results.
;	
;	ITEM_LIST will not work correctly if any of the BUFi arguments are
;	integers which, at the time ITEM_LIST is called, contain  hex val-
;	ues '010Ennnn' (where n is any digit).
;
;	.INDEX >>
;
;	Alan L. Zirkle     Naval Surface Weapons Center
;			   Code N41
;	14 May 1985	   Dahlgren, Virginia  22448
;

	$SSDEF

	.PSECT	$CODE, LONG,PIC,SHR,EXE,RD,NOWRT

	.ENTRY	ITEM_LIST, ^M<R2,R3,R4>

	MOVZBL	(AP), R0	; R0 = Count of arguments
	DECL	R0		; R0 = Count of arguments, minus one
	MOVAL	8(AP), R1	; R1 = Address of second argument's address
	MOVL	4(AP), R4	; R4 = Address of array to be filled

LOOP:
	SUBL	#2, R0		; Decrement argument count by 2
	BLSS	ERROR		; Branch if argument(s) missing
	MOVAW	@(R1)+, R3	; Get address of item code
	BEQL	ERROR		; Branch if argument is null
	MOVW	(R3), R3	; Get item code
	MOVAL	@(R1)+, R2	; R2 = Address of buffer (or buffer descriptor)
	BEQL	ERROR		; Branch if argument is null
	CMPW	2(R2), #^X010E	; Is this a string descriptor?
	BEQL	DESCR		; Branch if it is
	MOVW	#4, (R4)+	; Store length of 4
	MOVW	R3, (R4)+	; Store item code
	MOVL	R2, (R4)+	; Store longword's address
	CLRL	(R4)+		; Store null length return value address
	BRB	LOOPEND

DESCR:
	DECL	R0		; Decrement argument count by another 1
	BLSS	ERROR		; Branch if RLENi argument missing
	MOVW	0(R2), (R4)+	; Store length of string
	MOVW	R3, (R4)+	; Store item code
	MOVL	4(R2), (R4)+	; Store string's address
	MOVAL	@(R1)+, (R4)+	; Store return value address (may be null)

LOOPEND:
	TSTL	R0		; Are all arguments processed?
	BGTR	LOOP		; Loop if not
	CLRL	(R4)		; Insert zero item code as a terminator
	RET			; Return

ERROR:
	PUSHL	#SS$_INSFARG	; Signal SS$_INSFARG if the argument list
	CALLS	#1, G^LIB$SIGNAL ; is not correct.

	.END