.TITLE	HISTCL - HISTOGRAM CLEAR ROUTINE
	.IDENT	/04MAY7/	;15:30:00, EM
;	.ENTRY	HISTCL - HISTOGRAM CLEAR ROUTINE
;+
; H I S T C L
;
; PURPOSE:	THIS ROUTINE CLEARS A HISTOGRAM TO ZEROS. OVERFLOW
;		ENTRIES ASSOCIATED WITH THE HISTOGRAM ARE REMOVED
;		FROM THE OVERFLOW TABLE.
;
; INTERFACE:	CALLING SEQUENCE: (FORTRAN-CALLABLE SUBROUTINE)
;			CALL HISTCL(HDA)
;
;		INPUT:	HDA (INTEGER ARRAY): 
;			HISTOGRAM DESCRIPTOR ARRAY; EITHER THE
;			NAME OR THE NUMBER OF THE HISTOGRAM MAY
;			BE SPECIFIED.
;
;		EVENT FLAG 23. IS USED BY THIS SUBROUTINE.
;
; LANGUAGE:	MACRO-11
;
; REFERENCES:	"HISTOGRAMMING AND HISTOGRAM PLOTTING"
;		SEE SUBROUTINE HISTSU FOR A DESCRIPTION OF THE
;		HISTOGRAM DESCRIPTOR ARRAY.
;-
; REVISIONS:
; 06-JUN-75	MK	WRITTEN
; 04-MAY-77	EM	UPDATED TO CONFORM TO STANDARDS
;
HISTCL::
	CALL	HST$LK		;LOCK HDBS
	MOV	2(R5),R4	;GET HDA ADDRESS
	CALL	HST$FI		;FIND HDB
	BCS	RTN		;NO HISTOGRAM
	CALL	HST$CL		;CLEAR HISTOGRAM
RTN:	CALL	HST$UN		;UNLOCK HDBS
	RETURN
	.END