Recent Posts

31

Other Discussion / Re: framebuffer problem

« Last post by fredericopissarra on February 19, 2025, 11:10:33 PM »

Do you know If one of both framebuffer / sdl is faster as the other?

fbdev don't offer any acceleration support, not even in 2D like Bit Block Transfers (Bitblt)... SDL (2 and 3) does.

32

Other Discussion / Re: framebuffer problem

« Last post by andyz74 on February 19, 2025, 05:53:36 PM »

OK. I will check the Video drivers, If I manage to find Out how. 😂

Do you know If one of both framebuffer / sdl is faster as the other?

33

Other Discussion / Re: framebuffer problem

« Last post by fredericopissarra on February 19, 2025, 12:18:30 PM »

You have to make sure that your video drivers support /dev/fb? and make sure it is enabled in kernel configs, AND if it is accessible to your user...

It is better to use SDL2 (or 3, it is available now!).

34

Other Discussion / framebuffer problem

« Last post by andyz74 on February 18, 2025, 05:51:12 PM »

Hello and good evening!

I've done a little experimenting in doing easy graphic-stuff by writing direct to framebuffer /dev/fb0  (Debian Linux 64bit here)
Mainly in Free Pascal, before testing in Assembly.
While getting lots of garbage as output I also tested code, where I think it HAS to be good and HAS to work, I also got garbage.
( https://github.com/xmdi/SCHIZONE/tree/main/ex/ex020_framebuffer )   
If I test it on my Laptop (also Debian), it works, but not here on my beloved Desktopcomputer.

Now to my questions :
1) Is there anything I have to configure on my framebuffer in my Linux, and
2) Is it worth the time, or should I better invest time in SDL2 for doing graphics stuff?

Greetz, Andy

35

Programming with NASM / Re: Try Catch Exceptions implementation

« Last post by stephane on February 08, 2025, 01:56:23 PM »

Hi everyone!

I've been away for a long time (from programming, and from online social activities), due to personal reasons; I'm back with my desire to learn Assembly, again.
I've just seen your answers, and I just wanted to thank you, even if it comes 3 years later, I appreciate very much!

As for my question in this topic, I don't remember why I wanted to explore it, but your answers help me realize I have more important things to learn first, than trying to implement these kind of features.

Thank you all, for your courtesy, kindness, and interesting answers!

36

Programming with NASM / Re: Problem with calculating root

« Last post by andyz74 on January 30, 2025, 09:37:52 PM »

Main topic for me is  learning Assembler a bit. :-)
Good night now, in Germany we habe 10 pm, time to sleep.

37

Programming with NASM / Re: Problem with calculating root

« Last post by fredericopissarra on January 30, 2025, 08:44:01 PM »

I have another version of my program, in which I use the fp87 for getting the squareroot.  I test both.

The huge amount of divisions to see, what is prime and what not, is in the moment done by normal DIV command. But later, I will try to do this with fp87, and a third version to do it with sse2.

You don't need floating point or square root... Here:

Code: [Select]

_Bool isprime( unsigned int n )
{
  unsigned int d;
  unsigned long long int f;

  if ( n <= 3 )
    return n >= 2;

  d = n % 6;
  if ( d != 1 && d != 5 )
    return 0;

  for ( f = 5; f * f <= n; f += 2 )
    if ( ( n % f ) == 0 )
      return 0;

  return 1;
}

38

Programming with NASM / Re: Problem with calculating root

« Last post by andyz74 on January 30, 2025, 08:04:23 PM »

I have another version of my program, in which I use the fp87 for getting the squareroot.  I test both.

The huge amount of divisions to see, what is prime and what not, is in the moment done by normal DIV command. But later, I will try to do this with fp87, and a third version to do it with sse2.

39

Programming with NASM / Re: Problem with calculating root

« Last post by fredericopissarra on January 30, 2025, 07:44:59 PM »

A note of caution... If you intend to calculate the square root of an unsigned long long int, the double precision has only 53 bits of precision (while unsigned long long int has 64)... So the first example is insufficient: You need a bigger floating point precision that is not available to SSE... You must use fp87 instead:

Code: [Select]

; Input: RDI = x
; Output RAX = sqrt(x)
squareroot:
  fild qword [rsp-8],rdi   ; using red zone here.
  fsqrt
  fistp qword [rsp-8]
  mov rax,[rsp-8]
  ret

40

Programming with NASM / Re: Problem with calculating root

« Last post by andyz74 on January 30, 2025, 07:31:00 PM »

This works great! Many thanks, Frederico!

For learning purposes I try to make programs to find primes. And to reduce calculation times I will divide the actual number through a cycle from [sqrt(actual number)] downto 3.   (I test only the odd ones...)
Therefor I need to calculate the squareroots.

Many thanks, I've learned just a little bit. :-)