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tutorials: improve c2v tutorial a bit

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Alexander Medvednikov 2022-06-23 02:45:14 +03:00 committed by GitHub
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tutorials/C2V_translating_simple_programs_and_DOOM/README.md
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@ -10,6 +10,8 @@ https://www.youtube.com/watch?v=6oXrz3oRoEg
Let's start.
### A simple C program
First, We have a simple C program that prints prime numbers. It's a small program,
but it has some of the most widely used language features:
function definitions, control flow via for loops and if conditions, a libc function call,
@ -77,6 +79,7 @@ translated code all blocks are explicitely marked with brackets.
C2V successfully converts C's bool type to V's bool.
### Wrapper generation
C2V also has a wrapper generation mode.
@ -128,7 +131,7 @@ clean wrapper functions that can be called with `usersapi.create_user()` instead
Perhaps in the future C2V will translate C strings (char pointers) to V strings as well.
### Translating DOOM
All right, this works, and it's nice, but these are very trivial examples.
Let's try something a lot more fun, like the DOOM game.
@ -139,20 +142,21 @@ of the tools but also to have something to test via CI to avoid regressions.
During V's release we had lots of various examples, now for C2V we have DOOM.
This is the primary test of C2V.
DOOM is a very complex project that uses some really tricky elements of the C language.
And making sure C2V can always handle DOOM not only serves as a good C2V test but also
as a test of the V compiler itself, since it can run entire DOOM in pure V.
First let's download the DOOM source and build it to make sure everything works.
The original 1997 open source release doesn't work nicely on modern OSs, so the community
has been working on different forks. I'll be using Chocolate Doom, it's one of the most
popular forks, and its goal is to be as close to the original as possible
(they even keep the original bugs).
```bash
git clone https://github.com/vlang/doom
```
The main difference in this fork is using SDL for cross platform rendering, so we'll need
to install SDL2 before we can build it.
@ -163,7 +167,6 @@ into a single executable.
To build the C version:
```bash
git clone https://github.com/vlang/doom
cd doom/chocolate-doom
cmake .
make chocolate-doom
@ -192,27 +195,19 @@ This creates a new directory `src/doom/doom_v/`.
And we can use any name we want, there's a c2v configuration file.
`ls -alh src/doom/doom_v`
`ll src/doom/doom_v`
It has a bunch of files translated from C to V.
We can open any file, for example g_game.c and verify that it is indeed DOOM code
translated from C to V. It's also been nicely formatted by vfmt.
Now let's build it.
```bash
cd src/doom
sh build_doom_v.sh
```
I'll explain what we have in the shell script a bit later.
@ -228,11 +223,6 @@ and forcing a re-render.
There's a bug somewhere in C2V, it has just been released and needs some fixes.
Now let's look at those shell scripts and see how we built the V translation of DOOM.
C2V doesn't understand makefiles yet, so we have to do things manually.
@ -295,12 +285,7 @@ some V specific code, like a reversed V array.
Let's rebuild it and run again. As expected, we're getting our array printed every time an
enemy moves.
### Replacing C with V file by file
We translated the entire project. But sometimes it may be better to do more gradual transition
from C to V. For example, if you want to move your project from C to V, you might prefer doing
@ -327,14 +312,18 @@ processes. From C to V via C2V and then From V back to C again via the V compile
In fact we can actually look at the generated C code after all the translation and compare it
to the original. Very clean and barely changed:
![image](https://user-images.githubusercontent.com/687996/175178560-58e04248-bcb3-4e33-aebd-ad66bb94a887.png)
Both C2V and V generate clean human readable code.
https://twitter.com/v_language/status/1531816534011682821
The comments and C defines are missing right now, that's obviously something very nice to have,
so they will be translated as well.
### Conclusion
C2V has just been released on June 22th 2022, so it's going to mature with the help of
the community. With bug fixes and new C features supported, it should support the
entire C standard soon.