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/4	MACREL OVERLAY LOADER

/	.INCLUDE MGLOB

	.RSECT MACLOD
	FIELD 2

	.EXTERNAL OVRBLK
	.GLOBAL LOADY

	NUMRES=6	/NUMBER OF RESIDENT OVERLAY AREAS

/IF THE OVERLAY IS IN PLACE, WE BUMP ITS CORE ACCESS COUNT

/IF NOT, WE SEARCH RESLOC FOR IT (AT THE SAME TIME
/FINDING THE MINIMUM ACCESS COUNT)

/IF FOUND, WE SWAP CORE WITH THE RESIDENT OVERLAY

/IF NOT FOUND, WE SWAP CORE WITH THE MINIMUM GUY,
/DECREMENT ALL ACCESS COUNTS BY COUNT NOW IN CORE,
/AND BUMP THE CORE ACCESS COUNT (*** NOT QUITE IMPLEMENTED THIS WAY)


	SWYTO9=6	/***

ONE,	40		/ONE ACCESS INCREMENT
LOADY,	0
	DCA LOCO	/SAVE OVERLAY AREA (BITS 0-6) AND OVERLAY NUMBER (BITS 7-11)
	TAD LOCO
	AND (7740
	DCA OVRLOC	/GET OVERLAY LOCATION
	TAD I OVRLOC	/WHAT OVERLAY IS THERE?
	CIA
	TAD LOCO
	AND (37
	SNA CLA
	JMP THERE	/IT'S ALREADY THERE
	.IF NE NUMRES <
	TAD I (SWYTO9
	SPA CLA
	JMP SWAP	/NO RESIDENT OVERLAYS ON /Y
	CLA IAC
	DCA MIN		/NOT THERE
	DCA RESN
	DCA RESLOW
	DCA RESPTR
	TAD (-NUMRES
	DCA RESCNT
L$:	CDF 30
	TAD I RESPTR
	DCA RESACC	/GET OVERLAY AND ACCESS COUNT
	TAD RESACC
	CIA
	TAD LOCO
	AND (37
	SNA CLA		/IS THIS IT?
	JMP WASRES	/YES
	TAD RESACC	/NO
	AND (7740	/COMPARE ITS ACCESS COUNT
	STL CIA		/AGAINST ALL-TIME LOW
	TAD MIN
	SZL SNA CLA
	JMP 1$		/HIGHER
	TAD RESACC	/LOWER OR EQUAL
	AND (7740
	DCA MIN		/NEW MIN
	TAD RESN
	DCA RESLOW	/NEW LOW
1$:	TAD RESPTR
	TAD (400
	DCA RESPTR	/BUMP TO NEXT OVERLAY RESIDENCE
	ISZ RESN
	ISZ RESCNT
	JMP L$
/SHOULD DECREMENT ALL ACCESS COUNTS NOW BY MIN
	TAD RESLOW
	DCA RESN
	CDF 0
	TAD I OVRLOC
	SZA CLA		/NO NEED TO SWAP IF MEM=0
	JMS SWAPY
	>
SWAP,	TAD LOCO
	AND (37
	CDF 0
	TAD I (OVRBLK
	DCA OBLK	/GET BLOCK ON SYS DEVICE TO READ IN
	CDF 20
	CIF 0
	JMS I (7607
	200		/READ 2 PAGES
OVRLOC,	2000
TEMPO,
OBLK,	0
	HLT		/ER51
	.IF EQ 0 <
	CDF 0
	TAD I OVRLOC
	CIA
	TAD LOCO
	AND (37
	SZA CLA
	HLT		/GOT WRONG ONE
	>
THERE,	CDF 0
	TAD I OVRLOC	/BUMP ITS ACCESS COUNT
	TAD ONE
	DCA I OVRLOC
LODONE,	CIF CDF 0
	JMP I LOADY
RESPTR,	0
RESCNT,	0
LOCO,	0
RESACC,	0
RESN,	0
RESLOW,	0
MIN,	0

	.IF NE NUMRES <
WASRES,	JMS SWAPY
	JMP THERE

SWAPY,	0
	TAD OVRLOC
	DCA P1$
	TAD RESN
	CLL RTR
	RTR
	RAR		/*** ASSUMES START AT 0
	DCA P2$
	TAD (-400
	DCA KNT$
L$:	CDF 0
	TAD I P1$
	DCA TEMPO
	CDF 30
	TAD I P2$
	CDF 0
	DCA I P1$
	TAD TEMPO
	CDF 30
	DCA I P2$
	ISZ P1$
	ISZ P2$
	ISZ KNT$
	JMP L$
	JMP I SWAPY

P1$:	0
P2$:	0
KNT$:	0
	>
	PAGE