-- VersatectoPress.mesa - April 1980
-- Replacement versatec module to generate press files
-- Updated: February 6, 1981  3:26 PM

DIRECTORY
InlineDefs: FROM "InlineDefs" USING [LongCOPY],
PressDefs: FROM "PressDefs" USING[InitPressFileDescriptor,
	ClosePressFile, PressFileDescriptor, PutComputedDots],
ProcessDefs: FROM "ProcessDefs" USING [Detach, Yield],
SystemDefs: FROM "SystemDefs" USING [AllocateHeapNode, FreeHeapNode],
VersatecDefs: FROM "VersatecDefs";

Versatec: PROGRAM
IMPORTS InlineDefs, PressDefs, ProcessDefs, SystemDefs
EXPORTS VersatecDefs =
BEGIN OPEN InlineDefs, PressDefs, ProcessDefs, SystemDefs; 

StartVersatecPlot: PUBLIC PROCEDURE[fileName: STRING, width,height: CARDINAL] =
	BEGIN
	ScanLineLength _ (width+1)/16;
	ScanLine _ AllocateHeapNode[ScanLineLength];
	ScanLineReady _ TRUE;
	Done _ FALSE;
	Detach[FORK GeneratePressFile[fileName, width,height]];
	WHILE ScanLineReady DO Yield[]; ENDLOOP; --make sure GetLine is waiting
	END;

EndVersatecPlot: PUBLIC PROCEDURE =
	BEGIN
	FreeHeapNode[ScanLine];
	ClosePressFile[@pressFileDescriptor];
	END;

WriteVersatecLine: PUBLIC PROCEDURE [line: LONG POINTER, nBytes: CARDINAL] =
	BEGIN
	IF Done THEN RETURN;
	WHILE ScanLineReady DO Yield[]; ENDLOOP;
	LongCOPY[line, ScanLineLength, ScanLine];
	ScanLineReady _ TRUE;
	END;

--the following runs as a separate process, since PutComputedDots insists on having control
GeneratePressFile: PROCEDURE[fileName: STRING, width,height: CARDINAL] =
	BEGIN
	InitPressFileDescriptor[@pressFileDescriptor,fileName];
	PutComputedDots[@pressFileDescriptor,
		0,0,width,height,1,width,height,GetLine];
	Done _ TRUE;
	END;

GetLine: PROCEDURE RETURNS[POINTER] =
	BEGIN
	ScanLineReady _ FALSE;
	UNTIL ScanLineReady DO Yield[]; ENDLOOP;
	RETURN[ScanLine];
	END;

pressFileDescriptor: PressFileDescriptor;
ScanLine: POINTER _ NIL;
ScanLineLength: CARDINAL;
ScanLineReady: BOOLEAN;
Done: BOOLEAN;

-- *** START CODE ***

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