C	-+-+-+-+-+   H A E P T V . F T   -+-+-+-+-+
C
C	DISPLAYS THE SAMPLE BUFFER ONTO CRT 
C
C	UP 10-DEC-84 MORE SUPPORT OF THE FPP FACILITIES
C	UP 8-SEP-87 HA   REMOVING A PROGRAMMING ERROR
	SUBROUTINE PLOTTV
	INCLUDE HAEGSA.FI
	INCLUDE HAEBUF.FI
	INCLUDE HAEPTI.FI
	INCLUDE HABRK.FI
	INCLUDE HAETTY.FI
	REAL COND,XYSAM
	INTEGER NCOND
	EXTERNAL COND,NCOND,XYSAM
C
	INTEGER SAMBUF (2000),SAMBFL,	@ DISPLAY BUFFER SPACE, BUFFER LENGTH (CHANGE DATA STATEMENT TOO!)
     *  NUMCN,				@ NUMBER OF CHANNELS TO SCAN
     *  CO,CORD,CA,			@ CHANNEL OF THE ORDINATE, ABZISSE
     *  STEP				@ INCREMENT FOR SAMBUF SCAN & PLOT
	LOGICAL TIMABZ,TIMORD		@ ABZ., ORD. IS THE TIME BASE (COUNTS TO SAMCNT)
	REAL ORD,ABZ,			@ ORDINATE, ABZISSE
     *  DOWN,UP,LEFT,RIGHT 		@ SCREEN SCALING LIMITS
	DATA SAMBFL /2000/, STEP /3/
C
C
	IF (SAMCNT.EQ.0) RETURN		@ NO SAMPLE, RETURN
	IF (OPTION.NE.12) CALL ASKHIM (2) @ TV* SKIPS SOME QUESTIONS
	NUMCN=2				@ DEFAULT NUMBER OF CHANNELS TO SCAN
	CO=1
	CA=8
	WRITE (TTO,1) CA,CO,STEP		@ READ THE CHANNEL NUMBER OF THE DATA TO BE DISPLAYED
	READ (TTI,2) CA,CO,STEP
	STEP=NCOND(STEP,STEP,3)		@ INCREMENT DEFAULTS TO 3
	CO=NCOND(CO,CO,CA.GT.7,CO,CA+1)
	TIMABZ=CA.GT.7			@ ABZISSE IS A TIME SCALE
C	IF THE ABZISSE IS THE TIME AXIS THEN WE MAY PLOT MORE THAN ONE CHANNEL
	IF (.NOT.TIMABZ) GOTO 30
	WRITE (TTO,5) NUMCN		@ READ THE NUMBER OF CHANNELS TO SCAN
	READ (TTI,2) I
30	NUMCN=MIN0(CHNLS-CO,NCOND(.NOT.TIMABZ,1,I,I,NUMCN))
	TIMORD=CO.GT.7			@ ORDINATE IS THE TIME SCALE
C	COMPUTE THE SCREEN SCALING LIMITS
C	COMPUTE THE MARGIN OF PLOT EITHER -511,511 FOR AD VALUES OR TE1 FOR TIME SCALE
	UP   =COND(TIMORD,ENDS*SAMRAT,511.)
	DOWN =COND(TIMORD,FLOAT(BEGIN*SAMRAT),-511.)
	LEFT =COND(TIMABZ,FLOAT(BEGIN*SAMRAT),-511.)
	RIGHT=COND(TIMABZ,ENDS*SAMRAT,511.)
C
	CALL CLRPLT(SAMBFL,SAMBUF)	@ OPEN THE PLOT 
	CALL SCALE (LEFT,DOWN,RIGHT,UP)	@ SCALE THE SCREEN
C
	DO 10 I=BEGIN*SAMRAT,ENDS*SAMRAT-1,STEP
	IF BREAK(11) GOTO 20		@ USER ABORTS DISPLAY PLOT
	ABZ=COND(TIMABZ,FLOAT(I),XYSAM(I,CA))
	DO 10 CORD=CO,CO+NUMCN-1	@ LOOP FOR EACH CHANNEL
	ORD=COND(TIMORD,FLOAT(I),XYSAM(I,CORD))
	CALL PLOT (1,ABZ,ORD)		@ INSERT THE POINT INTO THE DISPLAY
10	CONTINUE
	WRITE (TTO,3)			@ WAIT TO CONTINUE
	READ (TTI,4)
20	CALL CLRPLT (0,SAMBUF)		@ SWITCH OFF THE DISPLAY
	RETURN
1	FORMAT (' KANAL DER ABZISSE/ORDINATE (ZEIT=8),'
     *  ' SCHRITTWEITE (3I1) (',
     *  3I1,')? ',$)
2	FORMAT (2I1,I3)
3	FORMAT (' BILD LANGE GENUG ANGESEHEN? ',$)
4	FORMAT ()
5	FORMAT (' ANZAHL DER DARZUSTELLENDEN KANAELE (I1) (',I1,
     *   ') ? ',$)
	END
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