Crosscompiling Flite TTS with Zig!

I ran into the Zig programming language recently. It is a general purpose programming language that claims to compete with C, but also is a C compiler. It comes with a build system that can build both zig projects as well as C projects. I usually work with Go, Python or C++ and decided to look into Zig.

I was particularly fascinated with Zig’s build system and support for crosscompilation. I watched a live stream by Zig’s creator in which they transitioned the build system of the redis project to zig and cross compiled it for macos from linux.

I wanted to try something similar: to see if I could build flite, a pure C project, using Zig. It went very smoothly indeed!

Step 1: Install zig #

Download Zig from their release page. At the time of writing, the latest stable release was 0.7.1, but the crosscompilation from linux to macos worked with the latest nightly release. A release newer than 0.8.0-dev.1544+867ae506e should be good.

Unzip the package and add the zig-*/zig binary to $PATH

Step 2: Download flite #

git clone https://github.com/festvox/flite

Step 3: Download the build.zig file #

Flite’s build system uses autoconf and make. I translated portions of the build into zig and published the build.zig as a gist on github. Note that this is not a full translation; but this should be enough for bulding flite with default languages and voices.

Download the gist in the flite directory:

cd flite

wget "https://gist.githubusercontent.com/happyalu/f1b5ecd4736e06f9fcdef710f292b6d3/raw/e23dcbfa73b0b1ce8836fe2924acd6ffac8e0418/build.zig"

Step 4: Build flite #

Assuming the zig binary is in $PATH, the following will compile and build the flite executable:

zig build 

The executable will be saved as zig-cache/bin/flite.

To test that it works, you can generate a test wav file and play it:

./zig-cache/bin/flite "hello world" hello.wav

As of writing this article, flite has a small bug that may cause the systhesis to fail with “Illegal Instruction”. If this bug hasn’t been fixed yet, try disabling the checks for undefined behavior:

zig build -Drelease-fast
./zig-cache/bin/flite "hello world" hello.wav

Step 5: Cross compilation #

I was able to cross compile flite for several architectures:

for host in \
    x86_64-linux-gnu \
    x86_64-macos \
    x86_64-windows-gnu \
    aarch64-linux-gnu \
    aarch64-macos; 
do
    zig build -Drelease-fast -Dtarget=$host; 
    mv zig-cache/bin/flite zig-cache/bin/flite-$host; 
done

I wasn’t able to compile this for the arm architecture, ran into this issue.

Remarks #

The Zig build system is amazing! Flite is written to be highly portable, so I was sure that there won’t be source changes required to get these builds going, but still, in the past, getting cross compilation to work properly has had been a hassle. It took me about an hour to translate flite’s build. Zig simplifies everything, makes cross compilation work with just a 37MB download, and even for the case to build for macos from linux! Go Zig!

This experiment mostly involved playing with Zig’s build system, and even if a project doesn’t use zig, it’s worth looking into using zig for the build. However, I do plan to take a deeper dive into Zig, the language, soon.