-- file:  LaurelSegments.mesa
-- edited by Levin, January 27, 1981  11:57 AM
-- edited by Brotz, September 18, 1980  11:57 AM

DIRECTORY
	AltoDefs: FROM "AltoDefs",
	AltoFileDefs: FROM "AltoFileDefs",
	crD: FROM "CoreDefs",
	exD: FROM "ExceptionDefs",
	lsD: FROM "LaurelStateDefs",
	SegmentDefs: FROM "SegmentDefs";

LaurelSegments: PROGRAM
	IMPORTS crD, exD, lsD, SegmentDefs
	EXPORTS lsD
	SHARES lsD =

BEGIN

OPEN lsD;

-- Exported procedures for clients --

DefineStateSegment: PUBLIC PROCEDURE [nPages: PageCount]
	RETURNS [seg: StateSegment] =
BEGIN
OPEN SegmentDefs;
IF ~beforeInstallation THEN exD.SysBug[];
seg _ AllocateStateNode[SIZE[StateSegmentObject]];
seg^ _
	[pages: nPages,
	link: NIL,
	body: inCore[fsh: NewFileSegment[stateFile, stateFF, nPages, Read+Write]]];
IF segmentListHead = NIL THEN segmentListHead _ seg
ELSE segmentListTail.link _ seg;
segmentListTail _ seg;
stateFF _ stateFF + nPages;
SetEndOfFile[stateFile, stateFF-1, AltoDefs.BytesPerPage];
END;  -- of DefineStateSegment --


SwapInStateSegment: PUBLIC PROCEDURE[segment: StateSegment]
	RETURNS [POINTER] =
BEGIN
OPEN SegmentDefs;
MakeSwappedIn[segment.fsh, DefaultBase, HardDown];
RETURN[FileSegmentAddress[segment.fsh]]
END;  -- of SwapInStateSegment --


StateSegmentAddress: PUBLIC PROCEDURE[segment: StateSegment]
	RETURNS [POINTER] =
BEGIN
IF segment.fsh.lock = 0 THEN exD.SysBug[];
RETURN[SegmentDefs.FileSegmentAddress[segment.fsh]]
END;  -- of StateSegmentAddress --


WriteStateSegment: PUBLIC PROCEDURE [segment: StateSegment] =
BEGIN
segment.fsh.write _ TRUE;
SegmentDefs.SwapUp[segment.fsh];
END;  -- of WriteStateSegment --


ReleaseStateSegment: PUBLIC PROCEDURE [segment: StateSegment] =
BEGIN
SegmentDefs.Unlock[segment.fsh];
END;  -- of ReleaseStateSegment --


-- Exported procedures private to the implementation --

segmentListHead, segmentListTail: StateSegment _ NIL;


InstallSegments: PUBLIC PROCEDURE [header: POINTER TO StateHeader] =
BEGIN
-- this uses an n^2 algorithm to discover the disk hints, but we don't care
-- how long installation takes.
seg: StateSegment;
fsh: SegmentDefs.FileSegmentHandle;
IF (header.segmentList _ segmentListHead) = NIL THEN RETURN;
header.firstSegmentPage _ segmentListHead.fsh.base;
FOR seg _ segmentListHead, seg.link UNTIL seg = NIL DO
	OPEN SegmentDefs;
	fsh _ seg.fsh;
	SwapIn[fsh];
	seg.hint _ GetFileSegmentDA[fsh];
	Unlock[fsh];
	DeleteFileSegment[fsh];
	ENDLOOP;
END;  -- of InstallSegments --


InitializeSegments: PUBLIC PROCEDURE [header: POINTER TO StateHeader] =
BEGIN
OPEN SegmentDefs;
seg: StateSegment;
fsh: FileSegmentHandle;
base: PageNumber _ header.firstSegmentPage;
IF beforeInstallation THEN beforeInstallation _ FALSE
ELSE exD.SysBug[];
FOR seg _ header.segmentList, seg.link UNTIL seg = NIL DO
	fsh _ NewFileSegment[stateFile, base, seg.pages, Read];
	SetFileSegmentDA[fsh, seg.hint];
	seg.fsh _ fsh;
	base _ base + seg.pages;
	ENDLOOP;
END;  -- of InitializeSegments --


-- Main program (executed by start trap) --

stateFF: PageNumber;
stateFile: PUBLIC SegmentDefs.FileHandle;
beforeInstallation: BOOLEAN _ TRUE;


Initialize: PROCEDURE =
BEGIN
byte: CARDINAL;
IF (stateFile _ crD.LookupInFileCache["Laurel.state"L]) = NIL THEN exD.SysBug[];
SegmentDefs.LockFile[stateFile];
SegmentDefs.SetFileAccess[stateFile, SegmentDefs.ReadWriteAppend];
[stateFF, byte] _ SegmentDefs.GetEndOfFile[stateFile];
IF byte ~= AltoDefs.BytesPerPage THEN exD.SysBug[]
ELSE stateFF _ stateFF + 1;
END;  -- of Initialize --


Initialize[];

END.z20461l3008(529)\f1