Removing a printf messes up the output (directx output) - Overclock.net

serge2k · 08-08-09

basically I'm just trying to create an emulator for space invaders, its coming along nicely except I decided to change the way I'm doing graphics because someone suggested to me that the new way would be faster.

What I was doing before was rendering every pixel as a vertex then outputting them as points. it worked but was slow.

So now I'm using a texture instead.

Anyway, I'm not going to post all of the code unless I absolutely have to but here is my problem

Code:

void Processor::Write_Byte(u8 val, u16 location)
{
	u16 tmp;
	if(location >= 0x4000)
	{
		tmp = location;
		location -= 0x2000;
	}
	else if(location >= 0x2000)
		tmp = location + 0x2000;
	else
	{
		return ;
	}
	
	
	if(location >= 0x2400 && location < 0x4000)
	{
		graphics->drawSprite(((location-0x2400)%32)*8,(location-0x2400)/32, val);
		
		printf("%d\t%d\n",(location-0x2400)%256,(location-0x2400)/256);
	}
	memory->Write(location, val);
	memory->Write(tmp, val);

}

all that function does is write to memory, handles the mirror, and if it is a write in the video memory it tells my graphics class to draw at a certain point.

The problem is that printf, I was using it for debugging but don't actually want it in the program. It's horrendously slow.

Here is the output from the first screen with the printf

here is it with the printf not executing (commented out)

oh and I realize that the first image still has problems, thats fine it's just the way the video memory is read. It's not an issue at this point as that is easy to correct.

At this point I'm completely confused why the printf can't be removed. It just seems weird.

Coma · 08-08-09

Paste working and non-working code, because you're probably accidentally changing something else that makes it break.

serge2k · 08-08-09

the only change is commenting out that printf.

works

Code:

void Processor::Write_Byte(u8 val, u16 location)
{
	u16 tmp;
	if(location >= 0x4000)
	{
		tmp = location;
		location -= 0x2000;
	}
	else if(location >= 0x2000)
		tmp = location + 0x2000;
	else
	{
		return ;
	}
	
	
	if(location >= 0x2400 && location < 0x4000)
	{
		graphics->drawSprite(((location-0x2400)%32)*8,(location-0x2400)/32, val);
		
		printf("%d\t%d\n",(location-0x2400)%256,(location-0x2400)/256);
	}
	memory->Write(location, val);
	memory->Write(tmp, val);

}

doesn't work

Code:

void Processor::Write_Byte(u8 val, u16 location)
{
	u16 tmp;
	if(location >= 0x4000)
	{
		tmp = location;
		location -= 0x2000;
	}
	else if(location >= 0x2000)
		tmp = location + 0x2000;
	else
	{
		return ;
	}
	
	
	if(location >= 0x2400 && location < 0x4000)
	{
		graphics->drawSprite(((location-0x2400)%32)*8,(location-0x2400)/32, val);
		
		//printf("%d\t%d\n",(location-0x2400)%256,(location-0x2400)/256);
	}
	memory->Write(location, val);
	memory->Write(tmp, val);

}

experimenting a bit

doesn't work

Code:

void Processor::Write_Byte(u8 val, u16 location)
{
	u16 tmp;
	if(location >= 0x4000)
	{
		tmp = location;
		location -= 0x2000;
	}
	else if(location >= 0x2000)
		tmp = location + 0x2000;
	else
	{
		return ;
	}
	
	
	if(location >= 0x2400 && location < 0x4000)
	{
		graphics->drawSprite(((location-0x2400)%32)*8,(location-0x2400)/32, val);
		
		printf("");
	}
	memory->Write(location, val);
	memory->Write(tmp, val);

}

works

Code:

void Processor::Write_Byte(u8 val, u16 location)
{
	u16 tmp;
	if(location >= 0x4000)
	{
		tmp = location;
		location -= 0x2000;
	}
	else if(location >= 0x2000)
		tmp = location + 0x2000;
	else
	{
		return ;
	}
	
	
	if(location >= 0x2400 && location < 0x4000)
	{
		graphics->drawSprite(((location-0x2400)%32)*8,(location-0x2400)/32, val);
		
		printf("t");
	}
	memory->Write(location, val);
	memory->Write(tmp, val);

}

works

Code:

void Processor::Write_Byte(u8 val, u16 location)
{
	u16 tmp;
	if(location >= 0x4000)
	{
		tmp = location;
		location -= 0x2000;
	}
	else if(location >= 0x2000)
		tmp = location + 0x2000;
	else
	{
		return ;
	}
	
	
	if(location >= 0x2400 && location < 0x4000)
	{
		printf("t");
		graphics->drawSprite(((location-0x2400)%32)*8,(location-0x2400)/32, val);
	}
	memory->Write(location, val);
	memory->Write(tmp, val);

}

rabidgnome229 · 08-09-09

Step through with a debugger and watch for what differs in the program state between the different versions

serge2k · 08-10-09

I tried stepping through and saw no difference.

heres the source for my chip8 emulator.

Spotswood · 08-11-09

Are you running this app on a multi-processor machine?

What happens if you replace the printf with this?

Code:

LONG dummy = 0;;
InterlockedIncrement(&dummy);

EDIT: After looking over your code some more, what happens if you write the log messages to a file rather than the console i.e. remove the call to AllocConsole() and change printf to fprintf.

serge2k · 08-11-09

The computer is the one in my sig, so yes it is on a dual core.

first suggestion didn't work. I tried just removing the allocconsole and printf statements and that didn't work.

08-11-09	#6 (permalink)
Spotswood Case Modder Join Date: Jul 2008 Location: New Hampshire, USA Posts: 236 Rep: 46 Unique Rep: 39 Trader Rating: 0	Are you running this app on a multi-processor machine? What happens if you replace the printf with this? Code: LONG dummy = 0;; InterlockedIncrement(&dummy); EDIT: After looking over your code some more, what happens if you write the log messages to a file rather than the console i.e. remove the call to AllocConsole() and change printf to fprintf. __________________ Rich Custom Wooden Case Builder Last edited by Spotswood : 08-11-09 at 12:14 AM

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Removing a printf messes up the output (directx output)

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