A2OS/source/Linker1.Mod

(* Aos, Copyright 2001, Pieter Muller, ETH Zurich *)

MODULE Linker1;	(* pjm *)

(* BootLinker for A2 - cf. Loader *)

IMPORT
	SYSTEM, Streams, Files, Commands, KernelLog := Linker0, Heaps := Linker0, Modules := Linker0, Linker0 ;

CONST
	Ok* = 0;
	FileNotFound = 1;
	TagInvalid = 2;
	FileCorrupt = 3;
	FileTooShort = 4;
	IncompatibleImport = 5;

	AddressSize = SIZEOF (ADDRESS);

	FileTag = 0BBX;				(* see PCM.FileTag *)
	NoZeroCompress = 0ADX;	(* see PCM.NoZeroCompress *)
	FileVersion = 0B1X;			(* see PCM.FileVersion *)
	FileVersionOC=0B2X; (* preparation for object and symbol file for new Oberon Compiler *)
	CurrentVersion=0B4X;

	MaxStructs = 1024;	(* maximum number of structures in export block *)

		(* object model exports *)
	EUEnd = 0;  EURecord = 1;  EUobjScope = 0;  EUrecScope = 1;  EUerrScope = -1;
	EUProcFlagBit = 31;

	Sentinel = LONGINT(0FFFFFFFFH);

TYPE
	ObjHeader = RECORD (* data from object file header *)
		entries, commands, pointers, types, modules, links, dataLinks: LONGINT;
		codeSize, dataSize, refSize, constSize, exTableLen, procs, maxPtrs, crc: LONGINT;
		staticTdSize: LONGINT;
		name: Modules.Name
	END;

	DataLinkRec = RECORD
		mod: LONGINT;
		entry: LONGINT;
		fixups: LONGINT;
		ofs: POINTER TO ARRAY OF SIZE
	END;

	LinkRec = RECORD
		mod: LONGINT;
		entry: LONGINT;
		link: SIZE
	END;

	TypeRec = RECORD
		init: BOOLEAN;
		entry, methods, inhMethods, baseMod: LONGINT;
		baseEntry: ADDRESS;
	END;

VAR
	trace: BOOLEAN;
(* ReadHeader - Read object file header. *)

PROCEDURE ReadHeader(r: Streams.Reader; VAR h: ObjHeader; VAR res: LONGINT);
VAR symSize: LONGINT; flags: SET; ignore: Modules.Module; tag: CHAR;
BEGIN
	r.Char(tag);
	IF tag = FileTag THEN
		r.Char(tag);
		IF tag = NoZeroCompress THEN r.Char(tag) END;	(* no zero compression in symbol file *)
		IF (tag = FileVersion) OR (tag >= FileVersionOC) & (tag <= CurrentVersion)  THEN
			IF tag = FileVersion THEN
			r.RawNum(symSize);
			ELSIF tag >= FileVersionOC THEN
			r.RawLInt(symSize)
			END;
			r.RawSet(flags);	(* compilation flags *)
			r.SkipBytes(symSize-4);	(* skip symbols *)
			r.RawLInt(h.refSize);
			r.RawLInt(h.entries);
			r.RawLInt(h.commands);
			r.RawLInt(h.pointers);
			r.RawLInt(h.types);
			r.RawLInt(h.modules);
			r.RawLInt(h.dataLinks);
			r.RawLInt(h.links);
			r.RawLInt(h.dataSize);
			r.RawLInt(h.constSize);
			r.RawLInt(h.codeSize);
			r.RawLInt(h.exTableLen);
			r.RawLInt(h.procs);
			r.RawLInt(h.maxPtrs);
			r.RawLInt(h.staticTdSize); (* ug *)
			IF ORD(tag) >= 0B4H THEN r.RawLInt(h.crc) END;
			r.RawString(h.name);
			IF trace THEN
				KernelLog.String("  name: ");  KernelLog.String(h.name);
				KernelLog.String("  symSize: ");  KernelLog.Int(symSize, 1);
				KernelLog.String("  refSize: ");  KernelLog.Int(h.refSize, 1);
				KernelLog.String("  dataSize: ");  KernelLog.Int(h.dataSize, 1);
				KernelLog.String("  constSize: ");  KernelLog.Int(h.constSize, 1);
				KernelLog.String("  codeSize: ");  KernelLog.Int(h.codeSize, 1);   KernelLog.Ln;
				KernelLog.String("  entries: ");  KernelLog.Int(h.entries, 1);
				KernelLog.String("  commands: ");  KernelLog.Int(h.commands, 1);
				KernelLog.String("  pointers: ");  KernelLog.Int(h.pointers, 1);
				KernelLog.String("  types: ");  KernelLog.Int(h.types, 1);
				KernelLog.String("  modules: ");  KernelLog.Int(h.modules, 1);
				KernelLog.String("  dataLinks: ");  KernelLog.Int(h.dataLinks, 1);
				KernelLog.String("  links: ");  KernelLog.Int(h.links, 1);  KernelLog.Ln;
				KernelLog.String("  exTableLen: "); KernelLog.Int(h.exTableLen, 1);
				KernelLog.String("  procs: "); KernelLog.Int(h.procs, 1);
				KernelLog.String("  maxPtrs: "); KernelLog.Int(h.maxPtrs, 1);
				KernelLog.String("  staticTdSize: "); KernelLog.Int(h.staticTdSize, 1); KernelLog.Ln;
				KernelLog.String("  crc: "); KernelLog.Hex(h.crc,-8); KernelLog.Ln
			END;
			IF r.res # Streams.Ok THEN res := r.res END
		ELSE
			res := TagInvalid
		END
	ELSE
		res := TagInvalid
	END
END ReadHeader;

(* zero compressed strings don't like UTF-8 encoding *)
PROCEDURE ReadString8(r: Streams.Reader;  VAR str: ARRAY OF CHAR);
VAR i: LONGINT;  ch: CHAR;
BEGIN
	i := 0;
	r.Char(ch);
	WHILE ch # 0X DO
		str[i] := ch; INC(i);
		r.Char(ch);
	END;
	str[i] := 0X;
END ReadString8;

PROCEDURE AllocateModule(m: Modules.Module; h: ObjHeader);
CONST
	LenOfs = 3 * AddressSize;	(* offset of dimension 0 in array header *)
	
VAR dataSize: SIZE; any: ANY;
	offset: ADDRESS;

	PROCEDURE NewSysArray(VAR ptr: ANY; elements, elemSize: SIZE);
	VAR adr: ADDRESS;
	BEGIN
		Heaps.NewSys(ptr, Heaps.ArraySize(elements, elemSize, 1));
		adr := SYSTEM.VAL(ADDRESS, ptr);
		SYSTEM.PUT(adr + LenOfs, elements);   (* dimension *)
	END NewSysArray;

	PROCEDURE NewPtrArray(VAR ptr: ANY; elements, elemSize: SIZE);
	VAR adr: ADDRESS;
	BEGIN
		IF elements = 0 THEN (* case of empty array is mapped to a SystemBlock *)
			NewSysArray(ptr, elements, elemSize)
		ELSE
			Heaps.NewRealArr(ptr, elements, elemSize, 1);
			adr := SYSTEM.VAL(ADDRESS, ptr);
			SYSTEM.PUT(adr + LenOfs, elements)  (* dimension *)
		END
	END NewPtrArray;

BEGIN
	dataSize := SYSTEM.VAL(SIZE, h.dataSize) + (-h.dataSize) MOD 8;	(* round up to 8 to align constant block *)

	NewSysArray(SYSTEM.VAL(ANY, m.entry), h.entries, SIZEOF(ADDRESS));
	NewSysArray(SYSTEM.VAL(ANY, m.command), h.commands, SIZEOF(Modules.Command));
	NewSysArray(SYSTEM.VAL(ANY, m.ptrAdr), h.pointers, SIZEOF(ADDRESS));
	NewPtrArray(SYSTEM.VAL(ANY, m.typeInfo), h.types, SIZEOF(Modules.TypeDesc));
	NewPtrArray(SYSTEM.VAL(ANY, m.module), h.modules, SIZEOF(Modules.Module));
	NewSysArray(SYSTEM.VAL(ANY, m.data), dataSize + h.constSize, 1);
	NewSysArray(SYSTEM.VAL(ANY, m.code), h.codeSize, 1);
	NewSysArray(SYSTEM.VAL(ANY, m.staticTypeDescs), h.staticTdSize, 1);
	NewSysArray(SYSTEM.VAL(ANY, m.refs), h.refSize, 1);
	NewSysArray(SYSTEM.VAL(ANY, m.exTable), h.exTableLen, SIZEOF(Modules.ExceptionTableEntry));

	(* the following code can be used in order to force a certain heapsize / alignment for debugging kernel issues
	IF m.name = "BootConsole" THEN 
		Heaps.NewSys(any, 0);	
	
		offset := SYSTEM.VAL(ADDRESS, any) - SYSTEM.VAL(ADDRESS, Heaps.heap); 
		offset := offset - 0EBE00H;
		offset := 4096 - offset;
		TRACE(offset);
		Heaps.NewSys(any,offset -32); 
		
	END;
	*)
	
	m.sb := ADDRESSOF(m.data[0]) + dataSize	(* constants positive, data negative *)
END AllocateModule;

(* ReadEntryBlock - Read the entry block. *)

PROCEDURE ReadEntryBlock(r: Streams.Reader;  m: Modules.Module): BOOLEAN;
VAR tag: CHAR;  i, num: LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 82X THEN	(* entry tag *)
		FOR i := 0 TO LEN(m.entry)-1 DO
			r.RawNum( num);
			m.entry[i] := num + ADDRESSOF(m.code[0])
		END;
		(*ASSERT((m.entries > 0) & (m.entry[0] = ADDRESSOF(m.code[0])));*)	(* entry[0] is beginning of code (cf. OPL.Init) *)
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadEntryBlock;

(* ReadCommandBlock - Read the command block. *)

PROCEDURE ReadCommandBlock(r: Streams.Reader;  m: Modules.Module): BOOLEAN;
VAR tag : CHAR; i, num : LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 83X THEN (* command tag *)
		FOR i := 0 TO LEN(m.command)-1 DO
			r.RawNum( num); m.command[i].argTdAdr := num;
			r.RawNum( num); m.command[i].retTdAdr := num;
			r.RawString( m.command[i].name);
			r.RawNum( num); m.command[i].entryAdr := num;
			(* addresses will be fixed up later in FixupCommands *)
		END;
		RETURN TRUE
	ELSE
		RETURN FALSE
	END;
END ReadCommandBlock;

(* ReadPointerBlock - Read the pointer block. *)

PROCEDURE ReadPointerBlock(r: Streams.Reader;  m: Modules.Module): BOOLEAN;
VAR tag: CHAR;  i, p: LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 84X THEN	(* pointer tag *)
		FOR i := 0 TO LEN(m.ptrAdr)-1 DO
			r.RawNum( p);
			ASSERT(p MOD AddressSize = 0);	(* no deep copy flag *)
			m.ptrAdr[i] := m.sb + p
		END;
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadPointerBlock;

(* ReadImportBlock - Read the import block. *)

PROCEDURE ReadImportBlock(r: Streams.Reader;  m: Modules.Module;  VAR res: LONGINT;
		VAR msg: ARRAY OF CHAR): BOOLEAN;
VAR tag: CHAR;  i: LONGINT;  name: Modules.Name;
BEGIN
	r.Char( tag);
	IF tag = 85X THEN	(* import tag *)
		i := 0;
		WHILE (i # LEN(m.module)) & (res = Ok) DO
			ReadString8(r, name);
			m.module[i] := Modules.ThisModule(name, res, msg);	(* recursively load the imported module *)
			INC(i)
		END
	ELSE
		res := FileCorrupt
	END;
	RETURN res = Ok
END ReadImportBlock;

(* ReadDataLinkBlock - Read the data links block. *)

PROCEDURE ReadDataLinkBlock(r: Streams.Reader;  dataLinks: LONGINT;  VAR d: ARRAY OF DataLinkRec): BOOLEAN;
VAR tag: CHAR;  i, j, num: LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 8DX THEN	(* data links tag *)
		FOR i := 0 TO dataLinks-1 DO
			r.Char( tag);  d[i].mod := ORD(tag);
			r.RawNum( num);  d[i].entry := num;
			r.RawLInt( num);  d[i].fixups := num; (* fixed size *)
			IF d[i].fixups > 0 THEN
				NEW(d[i].ofs, d[i].fixups);
				FOR j := 0 TO d[i].fixups-1 DO
					r.RawNum( num);  d[i].ofs[j] := num
				END
			ELSE
				d[i].ofs := NIL
			END
		END;
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadDataLinkBlock;

(* ReadLinkBlock - Read the link block. *)
PROCEDURE ReadLinkBlock(r: Streams.Reader;  links, entries: LONGINT; VAR l: ARRAY OF LinkRec; VAR f: ARRAY OF LONGINT; VAR caseTableSize: LONGINT): BOOLEAN;
VAR tag: CHAR;  i, num: LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 86X THEN	(* links tag *)
		FOR i := 0 TO links-1 DO
			r.Char( tag);  l[i].mod := ORD(tag);
			r.Char( tag);  l[i].entry := ORD(tag);
			r.RawNum( num);  l[i].link := num
		END;
		FOR i := 0 TO entries-1 DO
			r.RawNum( num); f[i] := num
		END;
		r.RawNum( caseTableSize);
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadLinkBlock;

(* ReadConstBlock - Read the constant block. *)

PROCEDURE ReadConstBlock(r: Streams.Reader;  m: Modules.Module; h: ObjHeader): BOOLEAN;
VAR tag: CHAR;  i: LONGINT; t: ADDRESS;
BEGIN
	r.Char( tag);
	IF tag = 87X THEN	(* constant tag *)
		t := m.sb;
		FOR i := 0 TO h.constSize-1 DO
			r.Char( tag);  SYSTEM.PUT(t, tag);  INC(t)
		END;
		SYSTEM.GET(m.sb, t);  ASSERT(t = 0);
		SYSTEM.PUT(m.sb, m);	(* SELF *)
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadConstBlock;

(* ReadExportBlock - Read the export block. *)

PROCEDURE ReadExportBlock(r: Streams.Reader;  m: Modules.Module): BOOLEAN;
TYPE ExportPtr = POINTER TO Modules.ExportDesc; (* this type is introduced to dereference fields of an ExportDesc variable *)
VAR tag: CHAR;  structs, i: LONGINT; struct: ARRAY MaxStructs OF ADDRESS;
	p {UNTRACED}: ExportPtr; (* this variable must be untraced since it will be casted from a pure address field, it is not a valid heap block *)

	PROCEDURE LoadScope(VAR scope: Modules.ExportDesc;  level, adr: LONGINT);
	VAR no1, no2, fp, off, num: LONGINT;
	BEGIN
		r.RawLInt( num);  scope.exports := num; (* fixed size *)
		no1 := 0;  no2 := 0;
		IF scope.exports # 0 THEN
			Linker0.NewExportDesc(scope.dsc, scope.exports);
			scope.dsc[0].adr := adr
		END;
		IF level = EUrecScope THEN
			INC(structs);  struct[structs] := SYSTEM.VAL(ADDRESS, ADDRESSOF(scope))
		END;
		r.RawNum( fp);
		WHILE fp # EUEnd DO
			IF fp = EURecord THEN
				r.RawNum( off);
				IF off < 0 THEN
					p := SYSTEM.VAL(ExportPtr, struct[-off]);
					scope.dsc[no2].exports := p.exports;
					scope.dsc[no2].dsc := p.dsc	(* old type *)
				ELSE
					LoadScope(scope.dsc[no2], EUrecScope, off)
				END
			ELSE
				IF level = EUobjScope THEN r.RawNum( num); scope.dsc[no1].adr := num END;
				scope.dsc[no1].fp := fp;  no2 := no1;  INC(no1)
			END;
			r.RawNum( fp)
		END
	END LoadScope;

BEGIN
	r.Char( tag);
	IF tag = 88X THEN	(* export tag *)
		structs := 0;
		FOR i := 0 TO MaxStructs - 1 DO struct[i] := Heaps.NilVal END;
		LoadScope(m.export, EUobjScope, 0);
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadExportBlock;

(* ReadCodeBlock - Read the code block. *)

PROCEDURE ReadCodeBlock(r: Streams.Reader;  m: Modules.Module): BOOLEAN;
VAR tag: CHAR;ignore: LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 89X THEN	(* code tag *)
		r.Bytes( m.code^, 0, LEN(m.code), ignore);
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadCodeBlock;

(* ReadUseBlock - Read and check the use block. *)

PROCEDURE ReadUseBlock(r: Streams.Reader;  m: Modules.Module;  VAR dataLink: ARRAY OF DataLinkRec;
		VAR res: LONGINT;  VAR msg: ARRAY OF CHAR): BOOLEAN;
VAR tag: CHAR;  i: LONGINT;  name, prevname: Modules.Name;  mod: Modules.Module;

	PROCEDURE Err;
	BEGIN
		IF res = Ok THEN
			res := IncompatibleImport;
			COPY(m.name, msg);  Modules.Append(" incompatible with ", msg);  Modules.Append(mod.name, msg);
		END
	END Err;

	PROCEDURE FixupCall(code: ADDRESS; link: SIZE; fixval: ADDRESS);
	VAR instr, nextlink: SIZE;  opcode: CHAR;
	BEGIN
		REPEAT
			SYSTEM.GET(code + link, instr);
			nextlink := instr;
			SYSTEM.GET(code + link - 1, opcode);	(* backward disassembly safe? *)
			IF opcode = 0E8X THEN	(* call instruction relative *)
				SYSTEM.PUT(code + link, fixval - (code + link + 4)) (* + 4: to next instruction *)
				(* relative, no further fixup required *)
			ELSE	(* move instruction absolute *)
				SYSTEM.PUT(code + link, fixval);
				Linker0.Relocate(code + link)
			END;
			link := nextlink
		UNTIL link = Sentinel
	END FixupCall;

	PROCEDURE FixupVar(code: ADDRESS; link: SIZE; fixval: ADDRESS);
	VAR i: LONGINT; val, adr: ADDRESS;
	BEGIN
		ASSERT(dataLink[link].mod # 0);	(* this must be non-local module (?) *)
		FOR i := 0 TO dataLink[link].fixups-1 DO
			adr := code + dataLink[link].ofs[i];
			SYSTEM.GET(adr, val);	(* non-zero for example with constant index into imported array *)
			SYSTEM.PUT(adr, val + fixval);
			Linker0.Relocate(adr)
		END
	END FixupVar;

	PROCEDURE CheckScope(scope: Modules.ExportDesc;  level: LONGINT);
	VAR fp, i, num: LONGINT; link, adr: SIZE; tdadr: ADDRESS;  tmpErr: BOOLEAN;
	BEGIN
		tmpErr := (level = EUerrScope);
		i := 0;  link := 0;
		r.RawNum( fp);
		WHILE fp # EUEnd DO
			IF fp = EURecord THEN
				r.RawNum( num); link := num;
				IF tmpErr THEN
					CheckScope(scope.dsc[i], EUerrScope)
				ELSE
					IF scope.dsc[i].dsc # NIL THEN
						IF link # 0 THEN
							adr := scope.dsc[i].dsc[0].adr;
							SYSTEM.GET(mod.sb + adr, tdadr);
							SYSTEM.PUT(m.sb-link, tdadr);	(* tdadr at tadr[0] *)
							Linker0.Relocate(m.sb-link)
						END
					END;
					CheckScope(scope.dsc[i], EUrecScope)
				END
			ELSE
				prevname := name; ReadString8(r, name);
				IF level >= EUobjScope THEN
					tmpErr := FALSE;
					IF level = EUobjScope THEN r.RawNum( num); link := num END;
					i := 0;  WHILE (i < scope.exports) & (scope.dsc[i].fp # fp) DO INC(i) END;
					IF i >= scope.exports THEN
						Err;  tmpErr := TRUE;  Modules.Append("/", msg);
						IF name = "@" THEN Modules.Append(prevname, msg)
						ELSE Modules.Append(name, msg)
						END;
						DEC(i)
					ELSIF (level = EUobjScope) & (link # 0) THEN
						IF ~(EUProcFlagBit IN SYSTEM.VAL(SET, link)) THEN
							FixupVar(ADDRESSOF(m.code[0]), link, mod.sb + scope.dsc[i].adr)
						ELSE
							FixupCall(ADDRESSOF(m.code[0]), SYSTEM.VAL(SIZE, SYSTEM.VAL(SET, link) - {EUProcFlagBit}),
								scope.dsc[i].adr + ADDRESSOF(mod.code[0]))
						END
					END
				END
			END;
			r.RawNum( fp)
		END
	END CheckScope;

BEGIN
	r.Char( tag);
	IF tag = 8AX THEN	(* use tag *)
		i := 0;
		ReadString8(r, name);
		WHILE (name # "") & (res = Ok) DO
			mod := Modules.ThisModule(name, res, msg);
			IF res = Ok THEN
				CheckScope(mod.export, EUobjScope)
			END;
			ReadString8(r, name);
		END
	ELSE
		res := FileCorrupt
	END;
	RETURN res = Ok
END ReadUseBlock;

(* ReadTypeBlock - Read the type block. *)

PROCEDURE ReadTypeBlock(r: Streams.Reader;  m: Modules.Module;  VAR type: ARRAY OF TypeRec): BOOLEAN;
VAR
	tag: CHAR;  i, j, newMethods, pointers, method, entry, num: LONGINT;
	tdSize: LONGINT; (* ug *)
	recSize, ofs, totTdSize (* ug *): SIZE; base: ADDRESS;
	name: Modules.Name;  flags: SET;
	startAddr, tdAdr: ADDRESS;
	staticTypeBlock {UNTRACED}: Heaps.StaticTypeBlock;
BEGIN
	r.Char( tag);
	IF tag = 8BX THEN	(* type tag *)
		totTdSize := 0;
		IF LEN(m.staticTypeDescs)  > 0 THEN
			startAddr := ADDRESSOF(m.staticTypeDescs[0]);
		END;
		FOR i := 0 TO LEN(type)-1 DO
			type[i].init := FALSE;
			r.RawNum(num); recSize := num;
			r.RawNum(num);  type[i].entry := num;
			r.RawNum(num);  type[i].baseMod := num;
			r.RawNum(num);  type[i].baseEntry := num;
			r.RawNum(num);  type[i].methods := ABS (num);
			IF num >= 0 THEN flags := {}	(* unprotected type *)
			ELSE flags := {Heaps.ProtTypeBit}	(* protected type *)
			END;
			r.RawNum(num);  type[i].inhMethods := num;
			r.RawNum(newMethods);
			r.RawLInt(pointers);  (* fixed size *)
			r.RawString(name);
			r.RawLInt(tdSize);	(* ug *)
			Heaps.NewTypeDesc(SYSTEM.VAL(ANY, m.typeInfo[i]), Modules.TypeDescRecSize);
			Heaps.FillStaticType(tdAdr, startAddr, SYSTEM.VAL(ADDRESS, m.typeInfo[i]), tdSize, recSize, pointers,
								Modules.MaxTags + type[i].methods);
			m.typeInfo[i].tag := tdAdr;	(* relocation done in Linker0.RelocateModule *)
			m.typeInfo[i].flags := flags;
			m.typeInfo[i].mod := m;		(* relocation done in Linker0.RelocateModule *)
			m.typeInfo[i].name := name;
			base := m.typeInfo[i].tag + Modules.Mth0Ofs; (* read new methods *)
			FOR j := 0 TO newMethods - 1 DO
				r.RawNum(method);
				r.RawNum(entry);
				SYSTEM.PUT(base - AddressSize * method, m.entry[entry]);
				Linker0.Relocate(base - AddressSize * method)
			END;
			(* other methods are left NIL *)
			staticTypeBlock := SYSTEM.VAL(Heaps.StaticTypeBlock, tdAdr);
			ASSERT(LEN(staticTypeBlock.pointerOffsets) = pointers);
			FOR j := 0 TO pointers - 1 DO
				r.RawNum(ofs);
				ASSERT(ofs MOD AddressSize  =  0);	(* no deep copy flag *)
				staticTypeBlock.pointerOffsets[j] := ofs;
				ASSERT(ADDRESSOF(staticTypeBlock.pointerOffsets[j]) < startAddr + tdSize)
			END;

			SYSTEM.PUT(m.sb + type[i].entry, m.typeInfo[i].tag); (* patch in constant area *)
			Linker0.Relocate(m.sb + type[i].entry);
			totTdSize := totTdSize + tdSize;
			startAddr := startAddr + tdSize;
		END;
		(*
		ASSERT(totTdSize  = m.staticTdSize);
		*)
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadTypeBlock;

(* ReadRefBlock - Read the reference block. *)

PROCEDURE ReadRefBlock(r: Streams.Reader;  m: Modules.Module): BOOLEAN;
VAR tag: CHAR; ignore: LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 8CX THEN	(* ref tag *)
		r.Bytes( m.refs^, 0, LEN(m.refs),ignore);
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadRefBlock;

(* FixupGlobals - Fix up references to global variables. *)

PROCEDURE FixupGlobals(m: Modules.Module;  VAR dataLink: ARRAY OF DataLinkRec);
VAR i: LONGINT; t: SIZE; adr: ADDRESS;
BEGIN
	IF dataLink[0].mod = 0 THEN	(* local module has globals *)
		FOR i := 0 TO dataLink[0].fixups-1 DO
			adr := ADDRESSOF(m.code[0]) + dataLink[0].ofs[i];
			SYSTEM.GET(adr, t);  SYSTEM.PUT(adr, t + m.sb);
			Linker0.Relocate(adr)
		END
	END
END FixupGlobals;

(* FixupLinks - Fix up other references. *)

PROCEDURE FixupLinks(m: Modules.Module;  VAR link: ARRAY OF LinkRec; VAR fixupCounts: ARRAY OF LONGINT; caseTableSize: LONGINT; VAR res: LONGINT);
VAR i: LONGINT;

	PROCEDURE FixRelative(ofs: SIZE; val: ADDRESS);
	VAR t: SIZE; adr: ADDRESS;
	BEGIN
		ASSERT(val # 0);
		WHILE ofs # Sentinel DO
			adr := ADDRESSOF(m.code[0])+ofs;
			SYSTEM.GET(adr, t);
			SYSTEM.PUT(adr, val - (adr+AddressSize));	(* relative => no relocation required *)
			ofs := t
		END
	END FixRelative;

	PROCEDURE FixEntry(ofs: SIZE; VAR fixupCounts: ARRAY OF LONGINT);
	VAR t: SIZE; adr: ADDRESS; i: LONGINT;
	BEGIN
		i := 0;
		WHILE ofs # Sentinel DO
			adr := ADDRESSOF(m.code[0])+ofs;
			SYSTEM.GET(adr, t);
			WHILE fixupCounts[i] = 0 DO INC(i) END;
			SYSTEM.PUT(adr, m.entry[i]);
			DEC(fixupCounts[i]);
			Linker0.Relocate(adr);
			ofs := t
		END
	END FixEntry;

	PROCEDURE FixCase(ofs: SIZE; caseTableSize: LONGINT);
	VAR i: LONGINT; t: SIZE; adr: ADDRESS;
	BEGIN
		i := caseTableSize;
		WHILE i > 0 DO
			adr := m.sb+ofs;
			SYSTEM.GET(adr, t);
			SYSTEM.PUT(adr, ADDRESSOF(m.code[0]) + t);
			Linker0.Relocate(adr);
			DEC(i);
			ofs := ofs + AddressSize
		END
	END FixCase;

BEGIN
	FOR i := 0 TO LEN(link)-1 DO
		ASSERT(link[i].mod = 0);	(* only fix local things *)
		CASE link[i].entry OF
			243..253: HALT(100); (*FixRelative(link[i].link, Modules.GetKernelProc(m, link[i].entry))*)
			|254: FixEntry(link[i].link, fixupCounts)	(* local procedure address *)
			|255: FixCase(link[i].link, caseTableSize)	(* case table *)
			ELSE res := 3406; RETURN				(* unknown fixup type *)
		END
	END
END FixupLinks;

(* When loader parsed the command block, the type descriptors have not yet been allocated so we could not fixup
the addresses -> do it now. *)
PROCEDURE FixupCommands(m : Modules.Module);
VAR i : LONGINT;
BEGIN
	FOR i := 0 TO LEN(m.command)-1 DO
		m.command[i].entryAdr := m.command[i].entryAdr + ADDRESSOF(m.code[0]);
		IF (m.command[i].argTdAdr > 1) THEN SYSTEM.GET(m.sb + m.command[i].argTdAdr, m.command[i].argTdAdr); END;
		IF (m.command[i].retTdAdr > 1) THEN SYSTEM.GET(m.sb + m.command[i].retTdAdr, m.command[i].retTdAdr); END;
	END;
END FixupCommands;

(* InitType - Initialize a type. *)

PROCEDURE InitType(m: Modules.Module;  VAR type: ARRAY OF TypeRec;  i: LONGINT);
VAR j, baseMod, extLevel: LONGINT; t, root, baseTag, baseMth, baseRoot: ADDRESS; baseM: Modules.Module;
BEGIN
	IF ~type[i].init THEN
		root := SYSTEM.VAL(ADDRESS, m.typeInfo[i].tag);
		baseTag := root + Modules.Tag0Ofs;
		baseMth := root + Modules.Mth0Ofs;
		baseMod := type[i].baseMod;  extLevel := 0;
		ASSERT(baseMod >= -1);
		IF baseMod # -1 THEN	(* extended type *)
			IF baseMod = 0 THEN	(* base type local *)
				j := 0;  WHILE type[j].entry # type[i].baseEntry DO INC(j) END;	(* find base type *)
				InitType(m, type, j);	(* and initialize it first *)
				baseM := m
			ELSE	(* base type imported *)
				baseM := m.module[baseMod-1];
				t := type[i].baseEntry;	(* fingerprint *)
				j := 0;  WHILE baseM.export.dsc[j].fp # t DO INC(j) END;	(* find base type *)
				type[i].baseEntry := baseM.export.dsc[j].dsc[0].adr
			END;
				(* copy base tags *)
			SYSTEM.GET(baseM.sb + type[i].baseEntry, baseRoot);
			SYSTEM.GET(baseRoot + Modules.Tag0Ofs, t);
			WHILE t # 0 DO
				SYSTEM.PUT(baseTag - AddressSize*extLevel, t);
				Linker0.Relocate(baseTag - AddressSize * extLevel);
				INC(extLevel);
				SYSTEM.GET(baseRoot + Modules.Tag0Ofs - AddressSize*extLevel, t)
			END;
				(* copy non-overwritten base methods *)
			FOR j := 0 TO type[i].inhMethods-1 DO
				SYSTEM.GET(baseMth - AddressSize*j, t);	(* existing method *)
				IF t = 0 THEN
					SYSTEM.GET(baseRoot + Modules.Mth0Ofs - AddressSize*j, t);	(* base method *)
					SYSTEM.PUT(baseMth - AddressSize*j, t);
					Linker0.Relocate(baseMth - AddressSize * j)
				END
			END
		END;
		m.typeInfo[i].flags := m.typeInfo[i].flags + SYSTEM.VAL(SET, extLevel);
		ASSERT(extLevel < Modules.MaxTags);
		SYSTEM.PUT(baseTag - AddressSize * extLevel, m.typeInfo[i].tag);	(* self *)
		Linker0.Relocate(baseTag - AddressSize * extLevel);
		type[i].init := TRUE
	END
END InitType;

PROCEDURE ReadExTableBlock(r: Streams.Reader;  m: Modules.Module): BOOLEAN;
VAR
	tag: CHAR;
	pcFrom, pcTo, pcHandler, i: LONGINT;
BEGIN
	r.Char( tag);
	IF tag = 8EX THEN
		FOR i:= 0 TO LEN(m.exTable) -1 DO
			r.Char( tag);
			IF tag = 0FEX THEN
				r.RawNum( pcFrom);
				r.RawNum( pcTo);
				r.RawNum( pcHandler);

				m.exTable[i].pcFrom := pcFrom + ADDRESSOF(m.code[0]);
				m.exTable[i].pcTo := pcTo + ADDRESSOF(m.code[0]);
				m.exTable[i].pcHandler := pcHandler + ADDRESSOF(m.code[0]);
			ELSE
				RETURN FALSE;
			END;
		END;

		RETURN TRUE
	ELSE
		RETURN FALSE
	END;
END ReadExTableBlock;

PROCEDURE ReadPtrsInProcs(r: Streams.Reader; m: Modules.Module): BOOLEAN;
VAR tag: CHAR; i, j, codeoffset, beginOffset, endOffset, nofptrs, p: LONGINT;
	procTable: Modules.ProcTable; ptrTable: Modules.PtrTable;

	PROCEDURE Max(i, j : LONGINT) : LONGINT;
	BEGIN
		IF i > j THEN
			RETURN i
		ELSE
			RETURN j
		END
	END Max;

	PROCEDURE SwapProcTableEntries(p, q : LONGINT);
	VAR procentry : Modules.ProcTableEntry;
		k, i, basep, baseq: LONGINT; ptr: SIZE;
	BEGIN
		k := Max(procTable[p].noPtr, procTable[q].noPtr);
		IF k > 0 THEN (* swap entries in ptrTable first *)
			basep := p * m.maxPtrs; baseq := q * m.maxPtrs;
			FOR i := 0 TO k - 1 DO
				ptr := ptrTable[basep + i];
				ptrTable[basep + i] := ptrTable[baseq + i];
				ptrTable[baseq + i] := ptr
			END
		END;
		procentry := procTable[p];
		procTable[p] := procTable[q];
		procTable[q] := procentry
	END SwapProcTableEntries;

	PROCEDURE SortProcTable;
	VAR i, j, min: LONGINT;
	BEGIN
		FOR i := 0 TO m.noProcs - 2 DO
			min := i;
			FOR j := i + 1 TO m.noProcs - 1 DO
				IF procTable[j].pcFrom < procTable[min].pcFrom THEN min:= j END
			END;
			IF min # i THEN SwapProcTableEntries(i, min) END
		END
	END SortProcTable;

BEGIN
	r.Char( tag);
	IF tag = 8FX THEN
		NEW(procTable, m.noProcs); NEW(ptrTable, m.noProcs * m.maxPtrs);	(* m.noProcs > 0 since the empty module contains the module body procedure *)
		FOR i := 0 TO m.noProcs-1 DO
			r.RawNum( codeoffset);
			r.RawNum( beginOffset);
			r.RawNum( endOffset);
			r.RawLInt( nofptrs);	(* fixed size *)

			procTable[i].pcFrom := codeoffset + ADDRESSOF(m.code[0]);
			procTable[i].pcStatementBegin := beginOffset + ADDRESSOF(m.code[0]);
			procTable[i].pcStatementEnd := endOffset + ADDRESSOF(m.code[0]);
			procTable[i].noPtr := nofptrs;
			FOR j := 0 TO nofptrs - 1 DO
				r.RawNum( p);
				ptrTable[i * m.maxPtrs + j] := p
			END
		END;
		SortProcTable();
		m.firstProc := procTable[0].pcFrom;
		FOR i := 0 TO m.noProcs - 2 DO
			procTable[i].pcLimit := procTable[i + 1].pcFrom
		END;
		procTable[m.noProcs - 1].pcLimit := ADDRESSOF(m.code[0]) + LEN(m.code) + 1; (* last element reserved for end of code segment,
																						  allow 1 byte extra, cf. Modules.ThisModuleByAdr *)

		(* in the dynamic loader, the following may not be executed while loading the pointers since a module might be loaded
			more than one times concurrently before effectively one of the loaded modules is loaded, cf. Modules.ThisModule.
			In the linker this can be done here already since we are sure we will publish this module in the list of modules.
			*)
		Linker0.InsertProcOffsets(procTable, ptrTable, m.maxPtrs);
		procTable := NIL; ptrTable := NIL;
		m.procTable := NIL; m.ptrTable := NIL;
		RETURN TRUE
	ELSE
		RETURN FALSE
	END
END ReadPtrsInProcs;

(** LoadObj - Load an Active Oberon object file. *)

PROCEDURE LoadObj*(name, fileName: ARRAY OF CHAR;  VAR res: LONGINT;  VAR msg: ARRAY OF CHAR): Modules.Module;
VAR
	f: Files.File;  r: Files.Reader;  h: ObjHeader;  m: Modules.Module; i, caseTableSize : LONGINT;
	dataLink: POINTER TO ARRAY OF DataLinkRec;
	link: POINTER TO ARRAY OF LinkRec;
	fixupCounts: POINTER TO ARRAY OF LONGINT;
	type: POINTER TO ARRAY OF TypeRec;
BEGIN
	f := Files.Old(fileName);
	IF f # NIL THEN
		IF trace THEN KernelLog.String("Loading ");  KernelLog.String(fileName);  KernelLog.Ln END;
		NEW(r,f,0);
		res := Ok;  msg[0] := 0X;
		ReadHeader(r, h, res);
		IF res = Ok THEN
			ASSERT(h.name = name);
			Linker0.NewModule(m);
			i := 0;  WHILE h.name[i] # 0X DO m.name[i] := h.name[i];  INC(i) END;
			m.name[i] := 0X;
			m.noProcs := h.procs;
			m.maxPtrs := h.maxPtrs;
			m.crc := h.crc;
			AllocateModule(m,h);
			IF trace THEN
				KernelLog.Address(ADDRESSOF(m.code[0]));  KernelLog.Char(" ");
				KernelLog.String(m.name);  KernelLog.Address(m.sb);  KernelLog.Ln
			END;
			NEW(dataLink, h.dataLinks);  NEW(link, h.links);   NEW(fixupCounts, h.entries); NEW(type, h.types);
			IF ReadEntryBlock(r, m) & ReadCommandBlock(r, m) & ReadPointerBlock(r, m) &
					ReadImportBlock(r, m, res, msg) & ReadDataLinkBlock(r, h.dataLinks, dataLink^) &
					ReadLinkBlock(r, h.links, h.entries, link^, fixupCounts^, caseTableSize) &
					ReadConstBlock(r, m,h) & ReadExportBlock(r, m) &
					ReadCodeBlock(r, m) & ReadUseBlock(r, m, dataLink^, res, msg) &
					ReadTypeBlock(r, m, type^) & ReadExTableBlock(r, m)  &
					ReadPtrsInProcs(r, m)  & ReadRefBlock(r, m) THEN
				IF h.dataLinks # 0 THEN FixupGlobals(m, dataLink^) END;
				IF h.links # 0 THEN FixupLinks(m, link^, fixupCounts^, caseTableSize, res) END;
				IF h.commands # 0 THEN FixupCommands(m); END;
				IF res = Ok THEN
					FOR i := 0 TO LEN(type^)-1 DO InitType(m, type^, i) END
				END
			ELSE
				IF res = Ok THEN res := FileCorrupt END
			END;
			dataLink := NIL;  link := NIL;  type := NIL
		END;
		IF (res # Ok) & (msg[0] = 0X) THEN COPY(fileName, msg);  Modules.Append(" corrupt", msg) END
	ELSE
		res := FileNotFound;  COPY(fileName, msg);  Modules.Append(" not found", msg)
	END;
	ASSERT(res = Ok);
	IF res # Ok THEN m := NIL END;
	RETURN m
END LoadObj;


BEGIN
	Modules.loadObj := LoadObj;
	trace := TRUE;
END Linker1.

(*
20.05.98	pjm	Started
*)

SystemTools.FreeDownTo  Linker1 Linker0 ~