C	PROGRAM GETI1.FT
C	---------------
C
C	PETER LEMKIN
C	IMAGE PROCESSING UNIT, DCBD
C	NATIONAL CANCER INSTITUTE
C	NATIONAL INSTITUTES OF HEALTH
C	9000 ROCKVILLE PIKE
C	BETHESDA, MD. 20014
C
C	NOV 14, 1977 /FROM BMIO.FT OF NOV 11, 1977
C
C
C	PURPOSE
C	-------
C	GETI1 (MEM,IBYTE,IX,IY) ==>I10 TO I18
C	DUBPLICATING POINTS ON THE BOUNDARY CONDITIONS.
C
C
C	NOTE: ARGUMENTS (MEM,IBYTE,IX,IY,
C		I10,I11,I12,...,I18) ARE PASSED THROUGH COMMON
C
C	NOTE: AUTO INDEX REGISTERS 10 THROUGH 17 ARE DESTROYED
C		IN GETI1 AND T3BUF I/O.
C
C	NOTE: THE MQ IS DESTROYED IN ALL CALLS.
C
C
C
C
C	1. (INTERNAL SUBR) R6BYTES - READ 3 CONSECUTIVE BYTES FROM
C			(MEM,IBYTE,IX,IY)==>CURRENT FIELD LOCS 10,11,12.
C
C	2. (INTERNAL SUBROUTINE) SETBADDR - COMPUTE AND LOAD
C			THE BM PIXEL ADDRESS (MEM&IY&IY)==>EXDMA[1:2];
C	OPDEFS
C	------
S	OPDEF	RIF	6224
C
S	OPDEF	TADI	1400
S	OPDEF	DCAI	3400
C
C
S	OPDEF	DMAGO	6070
S	SKPDF	DMASKP	6071
S	OPDEF	DMAWC	6072
S	OPDEF	DMACA	6073
S	OPDEF	DMACLR	6074
S	OPDEF	EXDMA1	6524
S	OPDEF	EXDMA2	6525
C
S	OPDEF	SWAB	7431
S	OPDEF	SWBA	7447
S	OPDEF	SHL	7413
S	OPDEF	ASR	7415
S	OPDEF	DAD	7443
S	OPDEF	DST	7445
S	OPDEF	DPIC	7573
S	OPDEF	CLAMQ	7621
C
S	OPDEF	MQA	7501
S	OPDEF	MQL	7421
S	OPDEF	BSW	7002
C
C
C	*********************************************************
C	SUBROUTINE:  G E T I 1					*
C	*********************************************************
C	GET CURRENT NEIGHBORHOOD AT (MEM,IBYTE,IX,IY) AND STORE IT IN
C
C		YM =	I13,I12,I11
C		Y  = 	I14,I18,I10
C		YP =	I15,I16,I17.
C
C	BOUNDARY CONDITIONS FOR REMAPPING PIXELS
C	----------------------------------------
C		LINE YM=-1 <==> LINE Y=0
C		LINE YP=256 <==> LINE Y=255
C		BOUNDARY POINTS XM=-1 <==> X=0
C		BOUNDARY POINTS XP=256 <==> X=255
C
S	ENTRY GETI1
S	CPAGE 2
S GETI1,	BLOCK 2
C
C	[1] SAVE IY,IX
S	TAD \IY
S	DCA 17
S	TAD \IX
S	DCA 16
C
C
C	[1.1] SETUP COMMAND WORD (IN C(13)) FOR USE IN R6BYTES
S	TAD \IBYTE
S	SZA CLA
S	TAD (0200 /HIGH BYTE
S	TAD (0200 /LOW BYTE
S	RIF /OR IN THE CURRENT DATA FIELD
S	DCA 15 /COMMAND WORD TO BE USED IN R6BYTES
C
C
C	[2] GET THE THREE PARTIAL LINES OF THE NEIGHBORHOOD
C
C	[2.1] GET I3,I2,I1 AT (IX-1,IY-1)
S	CLA CMA
S	TAD 16
S	SPA
S	CLA  /MAKE X =-1 ==> 0
S	DCA \IX
C
S	CLA CMA
S	TAD 17
S	SPA /IF < 0 THEN CLIP IY TO 0;
S	CLA
S	DCA \IY
C
S	JMS R6BYTES
C
C	COPY (10,11,12) INTO NEIGHBORHOOD
S	TAD 10
S	DCA \I13
S	TAD 11
S	DCA \I12
S	TAD 12
S	DCA \I11
C
C
C	[2.2] GET I4,I8,I0 AT (IX-1,IY)
S	TAD 17
S	DCA \IY
S	JMS R6BYTES
C
C	COPY (10,11,12) INTO NEIGHBORHOOD
S	TAD 10
S	DCA \I14
S	TAD 11
S	DCA \I18
S	TAD 12
S	DCA \I10
C
C
C	[2.3] GET I5,I6,I7 AT (IX-1,IY+1)
C	IF (IY_IY+1) > 255
C		THEN IY_255;
S	INC \IY
S	TAD \IY
S	TAD (-D256
S	SPA CLA
S	JMP R23OK
	IY=255
S R23OK,	JMS R6BYTES
C
C	COPY (10,11,12) INTO NEIGHBORHOOD
S	TAD 10
S	DCA \I15
S	TAD 11
S	DCA \I16
S	TAD 12
S	DCA \I17
C
C
C	[2.4] RESTORE X,Y BEFORE TEST X
S	TAD 17
S	DCA \IY
S	TAD 16 /SAVED X
S	DCA \IX
C
C
C	[3] FIX UP BOUNDARY PIXELS FOR X=0 AND X=255
C	NOTE: THE CASES FOR Y=0 AND Y=255 ARE HANDLED IN R3LINES.
S	CLA CMA
S	TAD \IX
S	SMA CLA
S	JMP \1302 /IX > 0
	I13=I12
	I14=I18
	I15=I16
	GOTO 1399
C
C
S\1302,	TAD \IX
S	TAD (-D256
S	SMA CLA
S	JMP \1399 /IX < 256
1303	I11=I12
	I10=I18
	I17=I16
C
C
S \1399,	RETRN GETI1
C	#########################################################
C	# INTERNAL SUBROUTINE:  R 6 B Y T E S
C	#########################################################
C	READ IBYTE PACKED OF (MEM&IY&IX):(MEM&IY&IX+5)==>LOC('10)[1:4],
C	THEN UNPACK THE THE 3 BYTES INTO 10, 11, 12.

C
C
S	CPAGE 3
S RR6BYTES,	JMP I R6BYTES
S R6BYTES,	0 /ENTRY
C
C	[1] SETUP GETI1 TO READ 6 BYTES ==> BUFF[1:4]
S	CLA CLL IAC RTL /LOAD 0004
S	DMAWC
C
S	TAD (10 /LOC '10 OF CURRENT FIELD
S	DMACA
C
C	SETUP THE BM I/O PIXEL ADDRESS (MEM&IY&IX)==>EXDAM[1:2];
C
S	TAD \MEM	
S	CLL RTL; RTL	/MOVE BITS [9:11] ==> [5:7]
S	MQL
S	TAD \IY
S	CLL RTR; RTR		/MOVE BITS [4:7] ==> [8:11]
S	AND (0017
S	MQA			/'OR'
S	EXDMA1			/HIGH-ORDER WORD
C
S	TAD \IY
C@S	CLL RTR; RTR; RAR	/MOVE BITS [8:11] ==> [0:3]
S	BSW; RTL		/    ALTERNATIVE MICROCODE SEQUENCE
S	AND (7400
S	TAD \IX
S	EXDMA2			/LOAD LO-ORDER WORD
C
C
S	TAD 15 /READ COMMAND WORD (SETUP BY GETI1)
S	DMAGO /READ (0000) 6 BYTES ==>BUFF[1:4]
S	DCA 7
C
S R6WAIT,	DMASKP
S	SKP
S	JMP \1800 /DONE
S	ISZ 7
S	JMP R6WAIT /NOT YET
S	JMP \100 /OVERFLOW
C
C
C	[2] UNPACK 1ST THREE BYTES ==> 10, 11, 12
S\1800,	TAD 16 /IF X=0, THEN UNPACK ONLY THE 2ND AND 3RD BYTES 
S			/FROM 1ST AND 2ND BYTES
S	SZA CLA
S	JMP \1801 /NORMAL UNPACKING
C
C	SPECIAL CASE OF X=0 (SO 1ST BYTE IS REALLY 2ND, 2ND IS
C	REALLY 3RD
C	NOTE BYTE IN 10 WILL BE TRASH
S	TAD 11 /X=1
S	AND (377
S	DCA 12
C
S	TAD 10 /X=0
S	AND (377
S	DCA 11
S	JMP RR6BYTES
C
C	NORMAL UNPACKING
S\1801,	TAD 10 /B3H&B1
S	RTR; RTR
S	AND (0360
S	MQL
S	TAD 11 /B3L&B2
C@S	RTL; RTL; RAL
S	BSW; RTR /ALTERNATIVE MICROCODE
S	AND (0017
S	MQA
S	DCA 12 /PASS BACK 3RD BYTE
C
S	TAD 10
S	AND (377
S	DCA 10
C
S	TAD 11
S	AND (377
S	DCA 11
C
C
C	RETURN
S	JMP RR6BYTES
C
C
C	****************** E R R O R ************************
S\100,	CLA
S	DMACLR
	WRITE(1,101)
101	FORMAT('GETI1 DMA ERR')
S	HLT
	GOTO 100
C
	END
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