Linux - Revision history

PoroCYon: /* Larger productions (1k and 4k intros) */

2025-04-23T13:06:18Z

‎Larger productions (1k and 4k intros)

2024-03-15T17:32:26Z

‎Additional Resources: add Tiny bitfield based text renderer

2022-02-11T00:28:22Z

‎Method 1: timerfd

2022-02-10T16:58:31Z

‎Method 1: timerfd: smaller setup code for timerfd

2021-12-27T21:48:45Z

‎Getting something on screen: Typo

2021-12-27T21:36:18Z

‎Syncing audio with visuals

2021-12-27T21:14:32Z

‎Getting the screen size: Fix typo

2021-12-27T21:11:57Z

Add code for getting the screen resolution

2021-12-04T02:28:46Z

‎Combining audio and video

2021-12-04T02:28:04Z

‎Method 3: shell loader

@@ Line 829: / Line 829: @@
 == Larger productions (1k and 4k intros) ==
 Creating 1k and 4k intros on linux usually requires a different setup, for more information on this check out the following links:
-* [https://linux.weeaboo.software/Home Linux Sizecoding wiki at weeaboo.software]
+* [https://in4k.github.io/wiki/linux in4k wiki page]
 * [https://pcy.ulyssis.be/pres/Lin.pdf The Intricacies of Sizecoding on Linux (PDF)]
 * [https://github.com/grz0zrg/tinycelfgraphics Collection of tiny C ELF programs with graphics output]

@@ Line 825: / Line 825: @@
 * [https://github.com/grz0zrg/tinycelfgraphics A dev/fb0 framebuffer binding + ELF header for small C programs]
 * [http://www.muppetlabs.com/~breadbox/software/tiny/teensy.html A Whirlwind Tutorial on Creating Really Teensy ELF Executables for Linux]
 == Larger productions (1k and 4k intros) ==

@@ Line 699: / Line 699: @@
      mov dl,8 ; num bytes to read, edx can be any value >= 8
      mov ecx,esp ; write timer expiration info to the stack
-     int 0x80
+     int 0x80 ; blocks until the next frame

@@ Line 682: / Line 682: @@
 <syntaxhighlight lang=nasm>
      ; assume this is placed at the beginning of the program (all registers zeroed)
-     mov ax,0x142 ; timerfd_create
+timer:
      int 0x80
-     mov ax,0x145 ; timerfd_settime
+main:
-     push ebx
+     xor eax,eax
-    push 1000000000/50 ; 50 fps
+     mov al,3 ; read syscall
-     push ebx
+     mov ebx,eax ; file descriptor of timer
-    mov bl,3 ; file descriptor of timer (returned by timerfd_create)
+     mov dl,8 ; num bytes to read, edx can be any value >= 8
-     mov edx,esp
+    mov ecx,esp ; write timer expiration info to the stack
      int 0x80
      jmp main

@@ Line 138: / Line 138: @@
 ==== Getting something on screen ====
-First we need to fill up our local memorybuffer with pixeldata, so lets start doing that using the old AND pattern
+First we need to fill up our local memorybuffer with pixeldata, so lets start doing that using the old XOR pattern:
 <syntaxhighlight lang=nasm>

@@ Line 658: / Line 658: @@
 === Syncing audio with visuals ===
-Coming soon...
+Syncing audio with visuals is unfortunately not as easy as one would hope. Unlike many oldskool platforms, you can't just write audio and video data in your main loop and have everything work out nicely. The reason for this is that the audio is buffered with a relatively large buffer size, which is not easy to change. The effect of this is that audio writes will succeed instantly without blocking until about 1 second of audio has been written, and then the next write will block for about 1 second. This process then repeats. As you can imagine this means the visuals will run at about 1 FPS.
 == Miscellaneous Techniques ==

@@ Line 804: / Line 804: @@
      mov ebx,0   ; ***PUT THE FILE DESCRIPTOR FOR /dev/fb0 HERE***
      xor ecx,ecx
-     mov ch,0x46 ; FBIOGET_FSCREENINFO
+     mov ch,0x46 ; FBIOGET_VSCREENINFO
      mov edx,esp
      int 0x80

@@ Line 794: / Line 794: @@
      int 0x80
 </syntaxhighlight>
 == Additional Resources ==

@@ Line 642: / Line 642: @@
 Although this method is already saving a lot of bytes, we haven't even gotten to the best part yet.
-We can use the shell loader to also set up the framebuffer for us and make it very convenient to use, by using only 11 extra bytes!
+We can use the shell loader to also set up the framebuffer for us and make it very convenient to use, by using only 10 extra bytes!
 To do this, just modify the loader as follows:

@@ Line 646: / Line 646: @@
 <syntaxhighlight lang=nasm>
-     db "cp $0 /tmp;sed -i 1d $_/$0;$_ 0>/dev/fb0|aplay",10
+     db "cp $0 /tmp;sed -i 1d $_/$0;$_<>/dev/fb0|aplay",10
 </syntaxhighlight>
-With this loader, you can use pwrite64 directly on file descriptor 0 (stdin) to write to the screen, and write to file descriptor 1 (stdout) to play audio.
+With this loader, you can use pwrite64 or mmap directly on file descriptor 0 (stdin) to write to the screen, and write to file descriptor 1 (stdout) to play audio.
 Just be careful to get the timing right if you're doing both audio and video, as the audio writes are blocking.