MODULE Kernel;

(*
	
	
*)
	IMPORT SYSTEM, Platform, Caches, Interrupts, GlobalTimer, Trace, Bit;

	CONST	
		kVersion* = "Ayk 1.0e";


	TYPE

		(* The prototype of an interrupt handler *)
		ExceptionHandler* = PROCEDURE {INTERRUPT} ( );

		(* The prototype of an interrupt handler *)
		Handler* = PROCEDURE();

		(* The prototype of a timer interrupt handler
			should be used to implement the scheduler *)
		TimerHandler* = PROCEDURE();

		(* The prototype of a trap handler
			As soon as the systen is up and running, a custom trap handler can be install *)
		TrapHandler* = PROCEDURE(type, adr, fp: LONGINT; VAR resFP: LONGINT);

		(* The prototype of a undefined instruction trap handler
			Can be used to decode custom instructions *)
		UDFHandler* = PROCEDURE(adr: LONGINT);

	VAR
		(* Consists of the delay used to call MicroWait(0)
			Is used to make MicroWait as accurate as possible *)
		delayCompensation: LONGINT;
		DelayDivisor: LONGINT;

		(* not necessary on ARM Cortex 9: we have an autoreset
		(* the time, when the next timer interrupt shall occur *)
		nextTimerInterrupt: LONGINT;
		*)

		(* main irq handlers *)
		irqHandlers: ARRAY Platform.MaxNumIrq OF Handler;

		(* Handlers for GPIO interrupts *)
		gpioHandlers: ARRAY Platform.NumGPIOPins OF Handler;

		(* The system time in milliseconds. Is updated by the primary timer interrupt
			handler *)
		timer: LONGINT;

		(* User installable handlers for timer, traps and Udefinded instruction traps *)
		timerHandler: TimerHandler; trapHandler: TrapHandler;
		udfHandler: UDFHandler;

		(* Temporary variable that stores the lnk register. Must be a global variable to be
			accessible in all processor modes *)
		lnk: PROCEDURE;
		cnt: LONGINT;
		snoop: LONGINT;
		lr: ADDRESS;
		
		toggle : BOOLEAN;

	(* Copy procedure like SYSTEM.MOVE. src and dst must be Aligned to LONGINT *)
	PROCEDURE Move*(src, dst, len: LONGINT);
		VAR i, word: LONGINT; chr: CHAR;
	BEGIN
		IF len > 0 THEN
			(* Copy Integerwise if possible *)
			IF (src MOD 4 # 0) OR (dst MOD 4 # 0) THEN
				WHILE len > 0 DO
					SYSTEM.GET(src, chr); SYSTEM.PUT(dst, chr);
					INC(src); INC(dst); DEC(len);
				END;
			ELSE
				i := len DIV 4;
				WHILE i > 0 DO
					SYSTEM.GET(src, word); SYSTEM.PUT(dst, word);
					INC(src, 4); INC(dst, 4); DEC(i);
				END;

				i := len MOD 4;
				WHILE i > 0 DO
					SYSTEM.GET(src, chr); SYSTEM.PUT(dst, chr);
					INC(src); INC(dst); DEC(i);
				END;
			END;
		END;
	END Move;

	(* Assumes interrupts are disabled *)
	PROCEDURE CleanCache*;	
	BEGIN
		Caches.CleanDCache();	
	END CleanCache;


	PROCEDURE EnableIRQs*;
	VAR cpsr: LONGINT;
	BEGIN
		SYSTEM.STPSR(0, cpsr);
		cpsr := SYSTEM.VAL(LONGINT, SYSTEM.VAL(SET, cpsr) - {7, 8});
		SYSTEM.LDPSR(0, cpsr);
	END EnableIRQs;

	(* Taken from Minos/Kernel.Mos *)
	PROCEDURE DisableIRQs*;
	VAR cpsr: LONGINT;
	BEGIN
		SYSTEM.STPSR(0, cpsr);
		cpsr := SYSTEM.VAL(LONGINT, SYSTEM.VAL(SET, cpsr) + {7, 8});
		SYSTEM.LDPSR( 0, cpsr);
	END DisableIRQs;


	
(*

	(* Enable the system clock *)
	PROCEDURE EnableIOCLK*;
	BEGIN
		GPIOInit(Platform.MHZ3686K, TRUE , 1);
	END EnableIOCLK;

	(* Enable/Disable the system clock to a specific device *)
	PROCEDURE EnableClock*(num: LONGINT; enable: BOOLEAN);
		VAR reg: SET;
	BEGIN
		IF(num >= Platform.MinValidClock) & (num <= Platform.MaxValidClock) THEN
			SYSTEM.GET(Platform.CKEN, reg);
			IF enable THEN reg := reg + {num} ELSE reg := reg - {num} END;
			SYSTEM.PUT32(Platform.CKEN, reg);
		END;
	END EnableClock;
	*)


(*
	PROCEDURE Timer0IrqHandler( );
	VAR a: SET;
	BEGIN
		(*Trace.StringLn("TimerIRQ");*)
		IF timerHandler # NIL THEN
			(* Context Switch *)
			SYSTEM.LDPSR( 0, Platform.SVCMode + Platform.IRQDisabled + Platform.FIQDisabled);
			lr := SYSTEM.LNK();
			SYSTEM.LDPSR( 0, Platform.SVCMode + Platform.FIQDisabled);
			timerHandler;
			(* Go back to IRQ mode Context Switch *)
			SYSTEM.LDPSR( 0, Platform.SVCMode + Platform.IRQDisabled + Platform.FIQDisabled);
			SYSTEM.SETLNK(lr);
			SYSTEM.LDPSR( 0, Platform.IRQMode + Platform.IRQDisabled + Platform.FIQDisabled);
		END;
		Trace.String(".");
	END Timer0IrqHandler;
	*)
	
	(* Get the internal hardware clock cycle counter *)
	PROCEDURE GetOSTimer*(): LONGINT;
		VAR i: LONGINT;
	BEGIN
		RETURN GlobalTimer.GetTimerLowValue();
	END GetOSTimer;
	
	PROCEDURE Reset*();
	BEGIN
	END Reset;

	(* the main interrupt timer routine. Used for doing the timecritical work in the main scheduler *)
	(*
	PROCEDURE Timer0IrqHandler;
	VAR lr, lirq, cpsr, fp: LONGINT;
	BEGIN

		(*
		Trace.String("0");
		INC(snoop);
		*)

		(* Set timer to new timeout *)
		nextTimerInterrupt := nextTimerInterrupt + (Platform.OSDELAY);

		(*
		IF ( snoop = 1 ) THEN
			Trace.String("N ");
			Trace.Hex( nextTimerInterrupt, -8);
			Trace.Ln;
			Trace.String(" O ");
			Trace.Hex( GetOSTimer(),-8);
			Trace.Ln;
		END;
		*)

		SYSTEM.PUT32( Platform.OSMR0, nextTimerInterrupt );

		(* clear match *)
		SYSTEM.PUT32(Platform.OSSR, 1); (* Clear Match *)
		SYSTEM.PUT32(Platform.OSIER, 1); (* Enable Interrupt on Match0 *)


		INC(timer, Platform.UNIT);
(*
		IF timerHandler # NIL THEN

			(*
			cpsr := Platform.SVCMode;
			cpsr := Bit.ORR(cpsr, 0C0H);
			SYSTEM.LDPSR(0, cpsr);
			*)

			CODE
				MRS	R0, CPSR
				BIC		R0,R0,#01FH	(* clear the mode bits 						*)
				ORR	R0,R0,#013H	(* enable supervisor mode 					*)
				ORR	R0,R0,#0C0H	(* disable IRQ 								*)
				MSR	CPSR_c,R0		(* store the status register 					*)
			END;

			lr:= SYSTEM.LNK();

			CODE
				MRS	R0, CPSR
				BIC		R0,R0,#0C0H	(* clear the IRQ bits, enable the global IRQ	*)
				MSR	CPSR_c,R0		(* store the status register 					*)
			END;

			(*
			SYSTEM.LDPSR(0, Platform.SVCMode );
			*)


			timerHandler;

			(*
			(* disable the IRQs *)
			SYSTEM.STPSR(0, cpsr);
			cpsr := Bit.ORR(cpsr, 0C0H);
			SYSTEM.LDPSR(0, cpsr);
			*)

			CODE
				MRS	R0, CPSR
				ORR	R0,R0,#0C0H	(* disable IRQ 								*)
				MSR	CPSR_c,R0		(* store the status register 					*)
			END;


			(* restore the link register *)
			SYSTEM.SETLNK( lr );

			CODE
				MRS	R0, CPSR
				BIC		R0,R0,#01FH	(* clear the mode bits, IRQ is still disabled	*)
				ORR	R0,R0,#012H	(* enable IRQ processor mode				*)
				MSR	CPSR_c,R0		(* store the status register 					*)
			END;

			(*
			(* return to IRQ mode *)
			SYSTEM.LDPSR(0, Platform.IRQMode + Platform.IRQDisabled+ Platform.FIQDisabled );
			*)

		END;
*)

	END Timer0IrqHandler;
*)



	(*
	(* Reset the watchdog. Do this periodically, otherwise the system will reboot *)
	PROCEDURE ResetWatchdog;
		VAR reg: LONGINT;
	BEGIN
		SYSTEM.GET(Platform.OSCR, reg);
		reg := reg + Platform.WatchdogTimerIntervall;
		SYSTEM.PUT32(Platform.OSMR3, reg);
	END ResetWatchdog;

	(* Enable the system Watchdog. Once enabled, the watchdog can only be disabled by rebooting the system *)
	PROCEDURE EnableWatchdog;
	BEGIN
		ResetWatchdog;
		(* Set bit 0 to enable the watchdog. The watchdog can only be disabled by resettting the cpu *)
		SYSTEM.PUT32(Platform.OWER, {0});
	END EnableWatchdog;

	(* Get the internal hardware clock cycle counter *)
	PROCEDURE GetOSTimer*(): LONGINT;
		VAR i: LONGINT;
	BEGIN
		SYSTEM.GET(Platform.OSCR, i); RETURN i
	END GetOSTimer;

	*)
	(* Wait uSec microseconds, max allowed is 429000 uSecs *)
	(* min @ 100Mhz is 2.1 usec *)
	(*
	PROCEDURE MicroWait*(uSec: LONGINT);
		VAR current, wait: LONGINT;
	BEGIN
		SYSTEM.GET(Platform.OSCR, current);
		wait := current +((uSec * DelayDivisor) DIV 1000H) - delayCompensation;
		REPEAT SYSTEM.GET(Platform.OSCR, current);
		UNTIL current > wait;
	END MicroWait;

	(* Wait mSec milliseconds *)
	PROCEDURE MilliWait*(mSec: LONGINT);
	BEGIN
		WHILE mSec > 0 DO MicroWait(1000); DEC(mSec); END;
	END MilliWait;

	(* Calculate the overhead of calling MicroWait(0) *)
	PROCEDURE SetDelayCompensation*;
		VAR startTime, stopTime: LONGINT;
	BEGIN
		delayCompensation := 0;
		DelayDivisor := ENTIER(REAL(Platform.CLOCKDIVISOR) / 2.44140625);

		DisableIRQs; SYSTEM.GET(Platform.OSCR, startTime); MicroWait(0);
		SYSTEM.GET(Platform.OSCR, stopTime); (*EnableIRQs; *)

		IF stopTime > startTime THEN delayCompensation := stopTime - startTime;
		ELSE delayCompensation := startTime - stopTime;
		END;
	END SetDelayCompensation;
	*)
	(* Get the system time in milliseconds, driven by the timer interrupt, rel to system boot up *)
	PROCEDURE GetTime*(): LONGINT;
	BEGIN
		RETURN timer
	END GetTime;
	
	PROCEDURE UpdateTime*( irq: LONGINT );
	BEGIN
		INC( timer );
		(*
		IF ( timer MOD 1000 ) = 0 THEN
			Trace.String("c");
		END;
		*)
		(*IF ( toggle ) THEN
			IoControl.ClearPin( 26 );
		ELSE
			IoControl.SetPin( 26 );
		END;
		
		toggle := ~toggle;*)
		
	END UpdateTime;
	
	PROCEDURE ShowTime*();
	BEGIN
		Trace.String("Time : "); Trace.Int( timer, 8 ); Trace.Ln;
	END ShowTime;
	


	(* Init the system *)
	PROCEDURE Init;
	VAR val: SET;
	BEGIN
		
		timer := 0;
		delayCompensation := 0;
		
		Interrupts.RegisterTimerHandler( UpdateTime );

		Trace.StringLn("Init Finished()");

	END Init;
	
	PROCEDURE EnableMMU*(translationBase, flags: ADDRESS);
	BEGIN
		Trace.String("tb = "); Trace.Hex(translationBase,-8); Trace.Ln;
		CODE
			ldr r0, [FP, #translationBase]
			orr r0, r0, #05BH
			mcr p15, 0, r0, c2, c0, 0

			mvn r0, #0 	; mmu domains: 1111 = manager
			mcr p15, 0, r0, c3, c0, 0

			ldr r0, [FP, #flags ]
			mcr p15, 0, r0, c1, c0, 0
		END;
		Trace.StringLn("enabled");
		(*
		dsb();
		isb();
		*)
	END EnableMMU;

	CONST
		PageTableBaseAddress = 10000000H - 100000H; (* 1 MB below highest address *);

	(* 1 MB page table entry *)
	PROCEDURE MapPage*(virtual, physical: LONGINT; flags: LONGINT);
	CONST
		PageSize = 100000H; (* 1 MB pages *)
	BEGIN
		ASSERT(virtual >= 0);
		ASSERT(virtual < 1000H);
		ASSERT(physical >= 0);
		ASSERT(physical < 1000H);

		SYSTEM.PUT(PageTableBaseAddress + virtual*4, physical * PageSize + flags);
		(*IF PageTableBaseAddress MOD 40H = 0 THEN
			UartMin.Str("map: "); UartMin.Hex(PageTableBaseAddress+virtual*4);
			UartMin.Str(" -> "); UartMin.Hex(physical*PageSize + flags);
			UartMin.Ln;
		END;
		*)
	END MapPage;

	CONST
		(* bits *)
		NS = 80000H;;
		nG = 20000H;
		S = 10000H;
		AP2 = 8000H;
		TEX = 1000H;
		AP = 400H;
		IMP = 200H;
		Domain = 20H;
		XN=10H;
		C=8H;
		B=4H;

		Section = 2;

		MappedCached* = B + AP*3H + TEX*5H + S + Section + 0FH * Domain;
		MappedNonCached* = Section;
		Unmapped* = 0;

BEGIN
	
	Trace.StringLn("Init kernel Init()");

	Init;
	
	toggle := FALSE;

	Trace.StringLn("Module init of kernel completed.");
	
END Kernel.