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steffest

Wanderings in Amiga dev-land

This is the Amiga Development blog of Steffest.
I'm a webdeveloper but have zero experience in C or developing for the Amiga.
These are my notes of the journey into Amiga dev-land.

The Goal:
To create a simple game from the same source files for 3 completely different target platforms:
a stock Amiga 500, a modern Mobile Phone and the Modern Web.

You are viewing the articles in chronological order.
You can also view them reversed, which might make more sense as a blog

kickstart

So ...
A new blog ...

I don't know anything about C.
Compiling a C program for me in the past was something like

  • install toolchain:
    • google
    • type "brew something something"
    • type "sudo brew something something"
    • wait 
    • wait in awe, wondering why on earth it has to pull in 4 GB of stuff to compile a few lines of code.
  • cd into src directory
  • type "make"
  • cross fingers and hope it works
  • if it doesn't work - go find someone who knows this stuff.

However ... as my interesting in all things computing expands, and one goes of to explore new systems, new OSses, new hardware, retro hardware, then one also discovers the itch to write some code for that platform.

I'm a web developer, the browser is my natural habitat and javascript is king, queen and army. Javascript runs on everything right!
Almost: it runs on any modern platform but it's complety useless on retro platforms like my first true love: the Amiga.

Of course, die-hard amiga developers work directly in assembly, but let's keep it somewhat portable and develop a new skillset that is usefull for the future.
Enter C - the one universal language that is truely present on all platforms.
As you can transpile C into javascript too these days, that seems like the perfect fit.
(Ok, I know maybe Pascal could also be a fit, but ... maybe later)

The goal:

To create a simple game from the same source files for these completely different target platforms, both retro and modern.

  • Amiga, because it's the coolest platform EVER. preferably as low as kickstart 1.3, but we'll settle for 3.1 for now.
  • Mobile, because it's the primary and ubiquitous platform. Android first, maybe iOS too if it's not too much trouble.
  • Web, because it's heaven: the one platform that's available to all, instantly, always, for free.

This blog is a log of my findings. 
To document the process from a total C-noob to a true cross-platform single-source app.

Let's do this!

Written on 23/01/2018 by steffest
amigatick

Of course, chasing the cross-platform dream is nothing new in the C-world.
There are lot's of examples out there and one that is particularly close to my own personal interest is "Emerald X11" by David Tritscher.

It's plain C, has full source code and is already targeted towards multiple platfoms, including amiga.
It has no javascript port yet but that's my cup of tea - Done!

Emscripten really is a very cool tool.
It's well documented and very easy to setup.

The hardest part is converting endless loops in C.
the Emerald X11 code has lot's stuff like.

While(){
   input = readInput();
   if (input>0) break;
}

This doesn't work in javascript.
javascript runs in a single thread and you can't use endless loops like this.
Instead, everything is event driven.
For games and other graphical stuff, there's usually a single function called by requestAnimationFrame to keep the UI in sync with the screen refresh rate. 
This means that you have to transform these c loops to functions that gets called 60 times a second using emscripten_set_main_loop.
This means converting an existing C source to javascript might require some restructuring.

As I'm starting from scratch, this is just something I need to be aware of from the start.

The source of Emerald X11 is very structured. 
It's a perfect example how to structure your code towards multiple compile targets.
There are usually the same kind of platform specific components needed in most types of software:

  • input
    • read user input like keyboard, mouse, joystick
    • reaad files
  • output
    • create a screen
    • display something on the screen
    • connect audio output
    • play an audio sample
    • write files

The goal is to wrap each of those components in a generic function that we can swap with another implementation when compiling for a platform.

in pseudo javascript:

Don't write

function movePlayer(){
     var canvas = document.getElementById("canvas");
     var context = canvas.getContext("2d");
     context.fillStyle = "black";
     canvas.drawRect(0,0,800,600)
     
     var playerImage = new Image();
     playerImage.src = "playerWalk.png";
     context.drawBitmap(playerImage,0,0,32,32,x,y,32,32);

     var audio = document.getElementById("audio");
     audio.src = "audio/walk.wav";
     audio.play();
}

but wrap everything in generic function like

function movePlayer(){
     clearScreen();
     drawSprite(SPRITE_PLAYER_WALK,x,y,32,32);
     playAudio(SAMPLE_WALK);
}

So you can write the entire game logic in C, controlled by a single "timer" function and do the platform specific implementation per platform.
An obvious no-brainer really - but still good to get clear from the start.

The web part of the project is covered. let's focus on the Amiga!

Written on 30/01/2018 by steffest
amigatick

Should I setup 1 dev environment so I can compile everything one the same platform?
This might seem the most logical setup but maybe not:

  • emscripten will always be a different compiler and a different path
  • I use osX, Windows en Ubuntu, depending on what I'm doing ... I want to fiddle with code on each of those platforms.
    javascript is the same everywhere, but C compilers are not ... keeping a dev tool chain up and running on those 3 platforms might more work then its worth - use Docker maybe?
  • I still have some real (physical) Amiga's ... it would be nice to code on them as well

Allthough there are some really interesting setup to compile amiga binaries on osX, widows and Linux, I ended up setting up a compiler on the amiga itself.

On the emulated amiga, I use a virtual harddisk that resides on Dropbox.
So whatever system I'm using, when I fire up an emulated amiga, it will always be the exact same setup on everyplatform because the hard disk file is synced.
Even more: after setup, I can just dump the content of the virtual harddisk onto a CF-card, pop it into a real amiga and BAM! everything is up and running there also (try doing THAT with a windows PC!)

All the source files are on Dropbox too, available both local and on the emulated amiga.
I can still use my editor of choice (Jetbrains FTW!) and compile it on the amiga.

If I'm REALLY eager, I can even run the virtual amiga on my Android phone - with the exact same virtual harddisk - and compile from there (OK, not very practical, but it's possible)

So let's keep Amiga compiling on the Amiga. 
We'll worry about mobile later.

 

Written on 10/02/2018 by steffest
amigatick

It seems there are 4 main options for Amiga C compilers

  • Sas/C
  • VBCC
    • made for cross platform compiling
    • needs addiotional header files from os3.9 NDK
    • it appears much easier to set this up outside the amiga using https://github.com/kusma/amiga-dev
    • works ... if I ever want to compile on windows this seems a good way.
  • Storm C
    • a full IDE - not really needed
    • V4 is still being sold here
    • Found V3 on http://www.amigafuture.de/downloads.php?view=detail&df_id=664 but could not get it to work
      • Ah ... the name of the install script is wrong (correct it in Install_storm_hd_english.info)


      • And the install script refers to the folder "StormC_3.0" instead of "StormC_3_0" ->rename it
      • Ok - it installs now.
      • Works: Simple Hello-word compiles and runs - Yay!
      • I like it. It seems to be the only mature C IDE on the Amiga?
      • emeraldX11 code barfs though ... to investigate.
  • GCC
    • the latest standalone version on aminet is 2.70, seems a bit old.
    • This package is promising: http://aminet.net/package/dev/gcc/ADE
      • Yes, this seems the one ... based on gcc 2.95
      • I like that you can just park it somwhere, run 1 "ADE-Startup" scriopt and everything works, nothing to install, nothing to configure.
      • I seems to compile the sources I used for my emscripten port nicely - ACE! Got myself a working Amiga binary.
    • Gcc 6.2 was ported back to 68k atari: http://d-bug.mooo.com/beyondbrown/post/gcc-6/ - cool!
    • also very cool ,to check out if I ever take on Assembler: online C to assembler tool: http://brownbot.hopto.org/


After some fiddling I decided to go with GCC 2.95 on the amiga.
Would there be any performance differences in the final binary when using different compilers? To test.

Update:

  • It appears Sas/C produces much smaller binaries than GCC
  • to autogenerate the smakefile use "mkmk" in the sourcedir
  • to build the smakefile use "smake"
  • bottom line: I like Sas/C - let's go with that.

Update2:

After some time I forgot how to get a SAS/C environment up and running when you start with a fresh Amiga system, so here's a reminder for myself.
SAS/C needs some assigns:

  • SC: - The main installation folder and assign containing the programs, libraries, headers and sample code.
  • SC:C - The compiler program files (added to path)
  • LIB: - The SAS/C and Amiga link library files
  • INCLUDE: - The C compiler and amiga NDUK header files
  • CXXINCLUDE: - The C++ compiler header files

In my case that adds to

ASSIGN SC: DH1:sc
ASSIGN LIB: DH1:sc/lib
ASSIGN INCLUDE: DH1:sc/include
ASSIGN CXXINCLUDE: DH1:sc/cxxinclude
PATH DH1:sc/c ADD

then use mkmk to generate a smakefile and smake to compile it

Written on 03/03/2018 by steffest
amigatick

Ok: Baby steps

Let's get the basics first: opening screens and windows, displaying something on the screen.
I've made a new repo on Github collecting all small examples.
If there are no building instructions you can compile them with:

  • Sas/C: type "mkmk" then "smake"
  • GCC: type "gcc -noixemul ****.c -o ****"

Let's not worry about portabilty at this point. The first goal is to get a program running that

  • runs fullscreen
  • displays an animated sprite 
  • listens for mouse and keyboard input
  • does some kind of performance test
  • exits gracefully on click

Maybe a bunnymark to test raw sprite perfomance?

My first semi-usefull program: detect if we are running on AGA Amiga or not. Yay! works fine.

Some interesting resources:

And some reading: 

Don't you love the internet!

Written on 07/04/2018 by steffest
amigatick

The trouble with stackoverflow is that is is an ungooglable error :-)

But lucky I found this:

http://www.amiga.org/forums/showpost.php?p=237540&postcount=14

I often see people define arrays of large size as local vars in a function, and they are unaware that this ends up in stack space.

Indeed! I tumbled into that booby trap also.
Note to self: define large data arrays as const outside any function.

It appears that GCC includes the standard C libraries libnix which defaults to V37 of Amiga libraries.
This makes it pretty hard to target kickstart 1.3 amigas as v37 was included with kickstart 2.04 ...
You can avoid this by using the -nostdlib flag but this opens a whole can of worms (no reference to __main, no reference to atexit ....)
So as a general rule: If you want to target kickstart 1.3 or lower: avoid GCC, use VBCC or SAS/C instead.

Written on 14/04/2018 by steffest
monitor_thumbsup

I started writing my own chunky versus planar rountine but ofcourse somebody already did that.
I found this totally execellent package at Aminet: GetImage: http://aminet.net/package/dev/c/GetImage
This takes an image (or multiple image inside a Dpaint Brush) and converts it to a C Image data structure ready to by used.
I you're starting with a .png file you can use e.g. Personal Paint to convert it to an DPaint brush.

On the amiga we can include this file and avoid having to do any (slow) chunky/planar conversions, on other platforms we can just include the original .png file.
Ecellent!

Written on 05/05/2018 by steffest
amigatick

Someone on the EAB board mentioned "Gamesmith Development System"
Normally I don't want to use "Frameworks" because I like to dig into it myself, but seeing I was having a hard time getting any kind of graphic performance out of my own code I decided to take a look.

I'm glad I did - it looks like it is the perfect "middleware" between high level C drawing function and the raw amiga specific stuff.
It's a library written in Assembler and C that exposes some basic graphic and audio functions to any other language that can load external libraries.
It comes with both a C and a Assemler compiler, but it also works with Sas/C

It was a commercial product but apparently it's in the public domain now.
I found the download here and the manual here.

The installation barfed on the final steps on my system, so I had to complete it manually: assign the GameSmith: path to the installation dir and rename the correct header file for use with Sas/C.

Some of the examples even are very "bunnymark" like so that looks really promising.
Gamesmith includes some "link" files you can excute, but I could not get them to work.
According to the Sas/C user guide you don't really need to do the compiling and linking in 2 steps, you can just use the sc command with the "link" parameter to do everyrthing in 1 step. 
You can use the "lib" parameter to define the include libraries.
So to compile the example it would be "sc file.c link lib GameSmith:GameSmith.lib to file"

Awesome. Gamesmith includes lot's of stuff I don't really need, I guess, but the base seems really really promising: fast and easy to integrate.

Let's give it a try.

Written on 26/05/2018 by steffest
amigatick

So this was released:

https://github.com/BartmanAbyss/vscode-amiga-debug

It's a plugin for Visual Studio Code that offers a complete and integrated Amiga Dev toolchain out of the box.
Including remote debugging and the whole shebang.

That's impressive .. and VERY comfortable I must say.

Just fire up VSCode, init a new Amiga project, hit F5 to run it and suddenly a virtual Amiga spins up, running your compiled code and offering a very cool remote debugging bridge right into your IDE.
It's magic!

It uses GCC to (cross) compile.

The IDE is the most important piece of the work flow for me. It's where you write your code and it just have to feel right.
For that reason, editing or writing code on the Amiga is a no go: there simply is no editor on the Amiga that even comes close to modern tools available today on windows/Mac/Linux.

My personal preference still are the JetBrains tools: IntelliJ, WebStom, CLion, PHPStorm ... These guys really understand the process of developing code.
They are not free but IMHO opinion totally worth it.

The other rising star is Visual Studio Code (not to be confused with the heavy weight Visual Studio)
It's biggest strenght is that it's free. 
It's fast, lightweight and extensible.
Good job, Microsoft!

Nervertheless... crosscompiling ... for some reason I still don't like it. Mainly because I switch systems/OS all the time and I like my tools to be completely platform independent.
VSCode is, but Bartmans toolchain is not (yet).
Having a light virtual Amiga around with Sas/C ready to roll feels more comfortable and more "in control" then a magically crosscompile toolchain.
Maybe I just have to dig in Bartmans tools some more to see how they work exactly.  

Written on 22/08/2019 by steffest
amigatick

After a hiatus I pickud up the Amiga-C-Compiler again.
One of the building blocks of many of my projects is the web: doing a HTTP request, parsing results, use them.
Once an application is "connected" in that way, it usually becomes so much more powerfull.
That's the same for the hardware.
I long thought networking on the Amiga was a gimmick, on of those "because-you-can" things that you fiddle with, get it working and hardly use after that.
But after you walked the upgrade-your-amiga-to-beast-mode path, networking is the main component that makes an Amiga fun to use.
Things like Samba shares, VNC, Synergy, streaming audio players, ... are just AWESOME on a high-spec amiga.

So today I finally managed to compile a program that does HTTP requests.
Yay, it even handles large binary files pretty well.
That was a nice deep dive on how HTTP works exactly on top of TCP/IP.  

Some notes.
I had to hunt for the correct include header files a lot, but I finally found them in the OS4 SDK at the Hyperion site. (It's in base.lha -> include -> netinclude)
Who knew OS4 would come in handy, right? Thank you Hyperion for still providing that kind of stuff.

Extract the files somewhere and include them in the compiler like

"sc INCLUDEDIR=NETINCLUDE:"

(where NETINCLUDE: is an assign the the location where you extracted the SDK)

Another resource I found very usefull was http://amigadev.elowar.com/ that has a hyperlinked copy of the Amiga RKM with lots of examples in C and the Amiga developer CD 2.1

S
o the next step: My program needs an interface!
At first sight that seems a bit messy on the Amiga ... you have GadTools , Boopsi, MUI classes,...
Seems like a LOT of boilerplate and hoops to jump through just to get some UI elements in the screen.
After all ... a button is just a rectangle with a label that should trigger some code when you click on it.
I think it was part of some presentation by FarbRausch where Chaos (I think) was giving some advice on coding.
If I look back on that, that talk had a great impact on the way I work now.

One advice was "build your own tools" , another advice was "build your own user interface system".
That seems like a really weird advice. Why reinvent the wheel, right?
The line of thinking was that - unless you build something very generic - you spend/loose a lot of time battling other peoples framework to do exactly what you want.
All those "generic UI systems" come with a lot of overhead and stuff you don't need, exactly because they aim to be ... well ... generic.
That's also what I did with Bassoontracker: just build your own UI library that does EXACTLY what you want without overhead.
I guess that's also a nice approach for Amiga applications.
In the end I think I want something like AmigaAmp, or the "Empy" skin of Eagleplayer where clearly the custom UI is a huge reason why these programs or fun to use.

That being said: If I ever go MUI - this resource seems very interesting.
And for GadTools: here's a list of useful demo/tuturial code

Written on 30/03/2020 by steffest
commodore

So I got myself a Rasberry Pi 4

I love it!
At first I was not impressed at all as it was very slow with the default raspian Linux, but then I tried DietPi - much better!
(And ofcourse Amiberry is also kind of cool)
I did have to fiddle a lot to get everything up and running though.

My main problem was that VNC did not work when no monitor was attached to the PI.

It worked fine when you connect a monitor, boot DietPi and disconnect te monitor, but not in complete headless mode.
after a loooooooon evening of trying and googling I finally found this post and this explanation.

So it's a bug in vncserver. The workaround that did the trick for me was to set the "view only" password as the normal password using vncpasswd.
When running headless, the VNC settings are in /DietPi/dietpi.txt - edit that to set the resolution and the screen ID (to 0 for easy of use): the config is in the main /DietPi/dietpi.txt
Then execute a "vncserver start" and a "vncserver stop"

More: the ssh client on the Amiga is to old I guess, but telnet works (I had to install the telnet deamon on the Pi).
to start Chromium with fullscreen enabled: chromium-browser --start-fulscreen (then F11, which is a bit annoying as the Amiga keyboard only goes to F10 :-))

More to come!

Written on by steffest


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