-- VMMgr>STLeaf.mesa (last edited by Knutsen on July 31, 1980 10:50 AM)

-- This interface defines types for the Heirarchy and Projection B-trees, and routines for creating, etc., leaves of the B-trees.

-- Note that the elements of a projection desc are a subset of the elements of a CachedRegion.Desc.

DIRECTORY

CachedRegion USING [State],

CachedSpace USING [Desc, Level],

Environment USING [Word, wordsPerPage],

VM USING [PageNumber];

STLeaf: DEFINITIONS =

BEGIN

ILeaf: TYPE = RECORD [CARDINAL]; -- index of a Leaf

PLeaf: TYPE = LONG POINTER TO Leaf; -- pointer to a Leaf

sizeLeaf: CARDINAL = Environment.wordsPerPage;

Leaf: TYPE = RECORD [SELECT OVERLAID * FROM

sTree => [

cDesc: CDesc, -- descriptors in use

descFirst: Desc ], -- first of array of bound Desc’s

free => [iLeafNext: ILeaf], -- next free page

fill => [ARRAY [0..sizeLeaf) OF RECORD [Environment.Word]], -- occupies a page

ENDCASE ];

sizeLeafBody: CARDINAL = SIZE[Leaf] - SIZE[CDesc];

CDesc: TYPE = CARDINAL; -- count of Descriptors

Kind: TYPE = {hierarchy, projection};

Desc: TYPE = RECORD [SELECT OVERLAID Kind FROM

hierarchy =>

[descH: CachedSpace.Desc],

projection => -- the elements of projection desc are a subset of the elements of CachedRegion.Desc.

[page: VM.PageNumber, -- key

level: CachedSpace.Level,

levelMapped: CachedSpace.Level,

hasSwapUnits: BOOLEAN,

state: ProjectionState,

writeProtected: BOOLEAN,

needsLogging: BOOLEAN ],

ENDCASE ];

alive: CachedRegion.State = CachedRegion.State[outAlive]; -- in the Projection, we only know that the region is some unknown flavor of alive (out, in, pinned).

ProjectionState: TYPE = CachedRegion.State[CachedRegion.State[unmapped]..alive];

Create: PROCEDURE RETURNS [ILeaf];

Delete: PROCEDURE [ILeaf];

Open: PROCEDURE [ILeaf] RETURNS [PLeaf];

Close: PROCEDURE [ILeaf];

END.

LOG

Time: May 16, 1978 11:21 AMBy: McJonesAction: Created file

Time: June 24, 1978 5:38 PMBy: McJonesAction: PageNumber moved to VM

Time: August 4, 1978 2:14 PMBy: McJonesAction: Added beingRemapped to projection Desc

Time: September 26, 1979 1:53 PMBy: KnutsenAction: Added hasSwapUnits, writeProtected to, deleted beingRemapped from projection Desc. Added alive.

Time: July 7, 1980 4:10 PMBy: GobbelAction: Added needsToBeLogged to projection Desc.

Time: July 31, 1980 10:50 AMBy: KnutsenAction: Made compatible with new CachedRegion.Desc.