N.B.: Under construction: I am happy with the code, but I need some time to write a series of articles explaining the things under the hood. It is highly likely that I'll extend the code to make the compiler optimising

current description draft (in russian) is available here: https://habr.com/ru/articles/786158/

tinycompiler - a 500-ish lines of code compiler in a weekend

Have you ever wondered how a compiler works? If so, this project is for you.

This weekend I'll write a compiler that translates a code written in a very simple programming language Wend (short for a week-end) into GNU assembly. This repository, however, will contain more than the final code. It will tell you a story about compilers.

So behold, here is a program that uses virtually all concepts in Wend:

main() {
    // square root of a fixed-point number
    // stored in a 32 bit integer variable, shift is the precision

    int sqrt(int n, int shift) {
        int x;
        int x_old;
        int n_one;

        if n > 2147483647/shift { // pay attention to potential overflows
            return 2 * sqrt(n / 4, shift);
        }
        x = shift; // initial guess 1.0, can do better, but oh well
        n_one = n * shift; // need to compensate for fixp division
        while true {
            x_old = x;
            x = (x + n_one / x) / 2;
            if abs(x - x_old) <= 1 {
                return x;
            }
        }
    }

    int abs(int x) {
        if x < 0 {
            return -x;
        } else {
            return x;
        }
    }

    // 25735 is approximately equal to pi * 8192;
    // expected value of the output is sqrt(pi) * 8192 approx 14519

    println sqrt(25735, 8192);
}

There will no be dynamic memory allocation, no pointers, no garbage collection. There will be nested functions, function overloading and type checking.

And as usual, there will be a program with a raytracer :)

run tests

make test

Graphics!

It is so dull to compute Fibonacci numbers, so here are more eyecandy examples for our compiler, check test-programs/gfx/*.wend files.

make gfx

Mandelbrot set

Zero-player breakout game

Fire

Sunset race

Metaballs