(* Minimal ELF header for self contained linux Oberon programs *)
(* Copyright (c) Felix Friedrich, ETH Zürich *)

MODULE Glue;

IMPORT SYSTEM, Trace;

CONST
	base* = 08048000H;
	debug* = {};
VAR
	last-: RECORD END; (* empty variable linked to end of kernel *)

	baseAdr*: ADDRESS;
	endAdr*: ADDRESS;

	dlsym-	: PROCEDURE {C} ( handle: ADDRESS; name: ADDRESS): ADDRESS;
	dlopen-	: PROCEDURE {C} ( pathname: ADDRESS; mode: LONGINT ): ADDRESS;
	dlclose-	: PROCEDURE {C} ( handle: ADDRESS );
	exit-		: PROCEDURE {C} (status: LONGINT);

	stackBottom-	: ADDRESS;	(* of main thread *)


	argc-: WORD;
	argv-: ADDRESS;
	environ-: ADDRESS;

	PROCEDURE {INITIAL, NOPAF} EntryPoint;
	CODE
	#IF I386 THEN
		; ELF header
		DB 07FH, 'ELF', 1, 1, 1, 0
		DD 0, 0
		DW 02, 03
		DD 01
		DD entry + base; program entry point
		DD elfheadersize
		DD 0
		DD 0
		DW elfheadersize
		DW 20H
		DW 3 ; #program header table entries
		DW 0
		DW 0
		DW 0

		elfheadersize:

		; program header
		DD 1
		DD 0
		DD base;
		DD base;
		DD @last - base; segment size (file)
		DD @last - base; segment size (memory)
		DD 07
		DD 1000H; alignment

		; interpreter header
		DD 3
		DD interpretername; interpreter name offset
		DD interpretername + base; interpreter name
		DD interpretername + base; interpreter name
		DD interpretername_end - interpretername ; interpreter name length
		DD interpretername_end - interpretername ; interpreter name length
		DD 4H
		DD 1H

		; dynamic header
		DD 02H
		DD dynamicsection
		DD dynamicsection + base
		DD dynamicsection + base
		DD dynamicsection_end - dynamicsection ; size of dynamic section
		DD dynamicsection_end - dynamicsection ; size of dynamic section
		DD 06H
		DD 04H

		dynamicsection:
		DD 05H, base + stringtable
		DD 06H, symboltablebegin + base
		DD 07H, dlsymrelocation + base
		DD 08H, dlsymrelocation_end-dlsymrelocation ; size (relocationtable)
		DD 09H, 0CH
		DD 0AH, stringtable_end - stringtable; size (stringtable)
		DD 0BH, 10H

		DD 01H, libname - stringtable; position of libname
		DD 0H, 0H ; sentinel
		dynamicsection_end:

	 	dlsymrelocation:
		DD @dlsym
		DB 01H
		DB 01H, 00H, 00H; index of the symbol
		DD 0H
		dlsymrelocation_end:

		stringtable:
		DB 0H ; sentinel

		libname:
		DB 'libdl.so.2', 0

		dlsymname:
		DB 'dlsym', 0


		stringtable_end:

		ALIGN 4
		symboltablebegin:
		DD	0;
		DD	0
		DD	0
		DB	0
		DB	0
		DW 0

		; dlsym symbol
		DD dlsymname - stringtable; position of dlsymname
		DD	0
		DD	0
		DB	12H ; info: global + function
		DB 0
		DW	0

		interpretername:
		DB '/lib/ld-linux.so.2', 0
		interpretername_end:

		ALIGN 4

		entry:
	#ELSIF AMD64 THEN
		; ELF header
		DB 07FH, 'ELF', 2, 1, 1, 0
		DD 0, 0
		DW 02, 62
		DD 01
		DQ entry + base; program entry point
		DQ elfheadersize
		DQ 0
		DD 0
		DW elfheadersize
		DW 38H
		DW 3 ; #program header table entries
		DW 0
		DW 0
		DW 0

		elfheadersize:

		; program header
		DD 1
		DD 07
		DQ 0
		DQ base;
		DQ base;
		DQ @last - base; segment size (file)
		DQ @last - base; segment size (memory)
		DQ 1000H; alignment

		; interpreter header
		DD 3
		DD 4H
		DQ interpretername; interpreter name offset
		DQ interpretername + base; interpreter name
		DQ interpretername + base; interpreter name
		DQ interpretername_end - interpretername ; interpreter name length
		DQ interpretername_end - interpretername ; interpreter name length
		DQ 1H

		; dynamic header
		DD 02H
		DD 06H
		DQ dynamicsection
		DQ dynamicsection + base
		DQ dynamicsection + base
		DQ dynamicsection_end - dynamicsection ; size of dynamic section
		DQ dynamicsection_end - dynamicsection ; size of dynamic section
		DQ 08H

		dynamicsection:
		DQ 05H, base + stringtable
		DQ 06H, symboltablebegin + base
		DQ 07H, dlsymrelocation + base
		DQ 08H, dlsymrelocation_end-dlsymrelocation ; size (relocationtable)
		DQ 09H, 18H
		DQ 0AH, stringtable_end - stringtable; size (stringtable)
		DQ 0BH, 18H

		DQ 01H, libname - stringtable; position of libname
		DQ 0H, 0H ; sentinel
		dynamicsection_end:

	 	dlsymrelocation:
		DQ @dlsym
		DD 01H
		DD 01H ; index of the symbol
		DQ 0H
		dlsymrelocation_end:

		stringtable:
		DB 0H ; sentinel

		libname:
		DB 'libdl.so.2', 0

		dlsymname:
		DB 'dlsym', 0


		stringtable_end:

		ALIGN 8
		symboltablebegin:
		DD	0;
		DB	0
		DB	0
		DW 0
		DQ	0
		DQ	0

		; dlsym symbol
		DD dlsymname - stringtable; position of dlsymname
		DB	12H ; info: global + function
		DB 0
		DW	0
		DQ	0
		DQ	0

		interpretername:
		DB '/lib64/ld-linux-x86-64.so.2', 0
		interpretername_end:

		ALIGN 8

		entry:
	#ELSE
		unimplemented
	#END
	END EntryPoint;

	(*
	PROCEDURE {FINAL} ExitPoint;
	BEGIN
		Trace.String("exiting"); Trace.Ln;
		exit(0);
	END ExitPoint;
	*)

	PROCEDURE putc*(file: ADDRESS; c: CHAR);
	CODE
	#IF I386 THEN
		MOV EAX, 4
		MOV EBX, [EBP + file]
		LEA ECX, [EBP + c]
		MOV EDX, 1
		INT 80H
	#ELSIF AMD64 THEN
		MOV EAX, 1
		MOV RDI, [RBP + file]
		LEA RSI, [RBP + c]
		MOV RDX, 1
		SYSCALL
	#ELSE
		unimplemented
	#END
	END putc;

	PROCEDURE Dlsym*(handle: ADDRESS; CONST name: ARRAY OF CHAR; adr: ADDRESS);
	VAR val: ADDRESS;
	BEGIN {UNCOOPERATIVE, UNCHECKED}
		val := dlsym(handle, ADDRESS OF name[0]);
		SYSTEM.PUT(adr, val);
	END Dlsym;

	PROCEDURE Char(c: CHAR);
	BEGIN {UNCOOPERATIVE, UNCHECKED}
		putc(1, c);
	END Char;

	PROCEDURE Init;
	VAR i: ADDRESS;
	BEGIN {UNCOOPERATIVE, UNCHECKED}
		baseAdr := ADDRESS OF EntryPoint;
		endAdr := ADDRESS OF last;

		Trace.Init;
		Trace.Char := Char;

		stackBottom := ADDRESSOF( i ) + 2*SIZEOF(ADDRESS);
		ASSERT(dlsym # NIL);
		Dlsym(0,"dlopen", ADDRESS OF dlopen);
		ASSERT(dlopen # NIL);
		Dlsym( 0, "dlclose", ADDRESS OF dlclose);
		ASSERT(dlclose # NIL);
		Dlsym(0,"exit", ADDRESS OF exit);
		ASSERT(exit # NIL);
	END Init;

	PROCEDURE {INITIAL,NOPAF} Init0;
	BEGIN {UNCOOPERATIVE, UNCHECKED}
		CODE
		#IF I386 THEN
			; argc at esp
			; argv at esp+4
			; 0 at esp+4+argc*4
			; env at esp+4+argc*4+4 = (2+argc)<<2 + esp
			MOV EAX, [ESP]
			MOV argc, EAX
			LEA EAX, [ESP+4]
			MOV argv, EAX
			MOV EAX, [ESP]
			ADD EAX, 2
			SHL EAX, 2
			ADD EAX, ESP
			MOV environ, EAX
		#ELSIF AMD64 THEN
			; argc at rsp
			; argv at rsp+8
			; 0 at rsp+8+argc*8
			; env at rsp+8+argc*8+8 = (2+argc)<<3 + rsp
			MOV RAX, [RSP]
			MOV argc, EAX
			LEA RAX, [RSP+8]
			MOV argv, RAX
			MOV RAX, [RSP]
			ADD RAX, 2
			SHL RAX, 3
			ADD RAX, RSP
			MOV environ, RAX
		#ELSE
			unimplemented
		#END
		END;
		Init;
	END Init0;

END Glue.



System.FreeDownTo FoxIntermediateBackend ~

System.DoCommands
	Compiler.Compile -p=Unix32
		I386.Builtins.Mod Trace.Mod Linux.Glue.Mod Linux.I386.Unix.Mod Unix.I386.Machine.Mod Heaps.Mod  Modules.Mod
		Unix.Objects.Mod
		Unix.Kernel.Mod KernelLog.Mod Plugins.Mod Streams.Mod
		Pipes.Mod Commands.Mod I386.Reals.Mod Reflection.Mod TrapWriters.Mod CRC.Mod SystemVersion.Mod
		Unix.StdIO.Mod Unix.Traps.Mod Locks.Mod Unix.Clock.Mod Disks.Mod Files.Mod Dates.Mod Strings.Mod
		UTF8Strings.Mod FileTrapWriter.Mod Caches.Mod DiskVolumes.Mod OldDiskVolumes.Mod RAMVolumes.Mod
		DiskFS.Mod OldDiskFS.Mod OberonFS.Mod FATVolumes.Mod FATFiles.Mod ISO9660Volumes.Mod
		ISO9660Files.Mod Unix.UnixFiles.Mod RelativeFileSystem.Mod BitSets.Mod StringPool.Mod DIagnostics.Mod
		ObjectFile.Mod GenericLinker.Mod Loader.Mod Unix.BootConsole.Mod
	~

	Linker.Link --fileFormat=Raw --fileName=simple_elf --extension=.GofU --displacement=08048000H
		Builtins Trace Glue Unix Machine Heaps Modules Objects Kernel KernelLog
Streams Commands StdIO TrapWriters Traps
Files UnixFiles Clock Dates Reals Strings Diagnostics
BitSets StringPool ObjectFile GenericLinker Reflection  Loader
BootConsole
 ~

	FSTools.CloseFiles simple_elf ~
~

MODULE Test;

IMPORT StdIO, Commands, Streams, Modules;

PROCEDURE Execute(context: Commands.Context);
VAR str, msg: ARRAY 256 OF CHAR;  res: WORD;
BEGIN
	IF ~context.arg.GetString(str) THEN RETURN END;
	IF ~context.arg.GetString(str) THEN
		context.out.String("no command"); context.out.Ln;
		RETURN
	END;
	Commands.Activate(str, context, {Commands.Wait}, res, msg);
END Execute;

BEGIN
	Execute(StdIO.env);
	Modules.Shutdown(1);
END Test.