NT_INTERRUPT issues

[Bearsoft749]

This code works in GCC 6.5 but does not work in GCC 13.1.
I must use "m68k-amigaos-strip" to get it to be executable in GCC 13.1.

#include <stdio.h>
#include <unistd.h>
#include <proto/exec.h>
#include <exec/execbase.h>
#include <hardware/intbits.h>

struct Interrupt *vbint2;
int counter;
int quit;
int value=0;
int valueEnd=60;

void startInterrupt(void *interruptFuncton)
{
 	vbint2=NULL;
                                                     
    if (vbint2 = (struct Interrupt *)AllocMem(sizeof(struct Interrupt), MEMF_PUBLIC|MEMF_CLEAR))
    {
        vbint2->is_Node.ln_Type = NT_INTERRUPT;
    
        vbint2->is_Node.ln_Pri = -60;	//-60
        vbint2->is_Node.ln_Name = "VertB";
        vbint2->is_Data = (APTR)&counter;
        vbint2->is_Code = (void (*)())interruptFuncton;

        AddIntServer(INTB_VERTB, vbint2); 
	}
	else 
	{
		printf("Can't allocate memory for interrupt node\n");	
	}
}

void endInterrupt()
{
	quit=1;

	 if (vbint2 != NULL)
	 {
        RemIntServer(INTB_VERTB, vbint2);
        FreeMem(vbint2, sizeof(struct Interrupt));
	
//        printf("%ld vertical blanks occurred\nRemoving server\n", counter);
	 }
}

int waitInterrupt()
{
	if (quit==2)
	{
		quit=0;
	}
	
	int tempQuit=quit;
	quit++;
	
	return tempQuit;
}

int interruptLoop()
{
	while(!waitInterrupt())
	{
		value++;
		
		if (value>=valueEnd)
		{
			value=valueEnd;
		}
	}
}

int main()
{
	startInterrupt((void*)interruptLoop);

	while(value<valueEnd)
	{
		sleep(3);
	}

	endInterrupt();

	printf("value %d\n", value);
	
	return 0;
}

[Bearsoft749]

I forgot...
m68k-amigaos-g++ -w -O3 -mno-align-int -funsafe-math-optimizations -ffast-math -mhard-float -fomit-frame-pointer -m68060 -noixemul -o main main.cpp

[bebbo]

please check again

[Bearsoft749]

It doesn't work... It works in 6.5.

[Bearsoft749]

GCC6.5 with -S option

main6.5.txt

GCC13.1.1 with -S option

main13.1.1.txt

[Bearsoft749]

You can use WinMerge to compare...

[bebbo]

What should the program do? And what is the problem?

Doesn't work is not precise enough.

[Bearsoft749]

It's a vertical blank interrupt.
https://en.wikipedia.org/wiki/Vertical_blank_interrupt

http://amigadev.elowar.com/read/ADCD_2.1/Includes_and_Autodocs_2._guide/node0326.html

It doesn't work. AmigaOS crashes if you try to run it.

Same with the function CreateNewProc

http://amigadev.elowar.com/read/ADCD_2.1/Includes_and_Autodocs_2._guide/node028D.html

[cdhooper]

@Bearsoft749 pardon my lack of knowledge, but how does interruptLoop() get a pointer to your program globals?
I was under the impression that an AmigaOS interrupt handler functions are not in the context of the calling task, but rather receive in register a1 a pointer to the is_Data that was initialized when AddIntServer() was called. If that is the case, then I think your interruptLoop() might be out there incrementing random memory, which happens to be relative to the context of the running code which was just interrupted.

[bebbo]

did you read the linked documents?

Each link in the chain will be called in priority order until the
    chain ends or one of the servers returns with the 68000's Z condition
    code clear (indicating non-zero).  Servers on the chain should return
    with the Z flag clear if the interrupt was specifically for that
    server, and no one else.  VERTB servers should always return Z set.
    (Take care with High Level Language servers, the language may not
    have a mechanism for reliably setting the Z flag on exit).

WARNING
    Some compilers or assemblers may optimize code in unexpected ways,
    affecting the conditions codes returned from the function.  Watch
    out for a "MOVEM" instruction (which does not affect the condition
    codes) turning into "MOVE" (which does).

It's not safe to write interrupt routines in C/C++. Guess you need some asm wrapper to set the Z flag properly!

[bebbo]

Oh wait! There is __interrupt. Add it to the interrupt function and it's ok.

[cdhooper]

Oh wait! There is __interrupt. Add it to the interrupt function and it's ok.

I believe the _interrupt attribute will end the function with an rte instead of rts, which is not desirable for an AmigaOS interrupt handler. Works great, though, if you are implementing your own vector handler.

[bebbo]

Oh wait! There is __interrupt. Add it to the interrupt function and it's ok.

I believe the _interrupt attribute will end the function with an rte instead of rts, which is not desirable for an AmigaOS interrupt handler. Works great, though, if you are implementing your own vector handler.

you are right, that would end in a rte...

[bebbo]

then something like

extern "C" int __interruptLoop()
{
  // what eva?
}

int interruptLoop() {
    asm volatile ("bsr ___interruptLoop");
    return 0;
}

should do it an clear the Z flag

[cdhooper]

Great idea!
For extra confidence, one could add "attribute((noinline))" to the called __interruptLoop() function.