feat(compiler): Add support for targeting WebAssembly.

The working principle is similar as before with x86, but instead of outputting .asm, it outputs .wat. This can be compiled into .wasm by using the wat2wasm assembler.

README.md

@@ -1,8 +1,10 @@
 # Sointu
 ![Tests](https://github.com/vsariola/sointu/workflows/Tests/badge.svg)
 
-A cross-platform modular software synthesizer for small intros, forked from
-[4klang](https://github.com/hzdgopher/4klang). Supports win32/win64/linux/mac.
+A cross-architecture and cross-platform modular software synthesizer for small
+intros, forked from [4klang](https://github.com/hzdgopher/4klang). Targetable
+architectures include 386, amd64, and WebAssembly; targetable platforms include
+Windows, Mac, Linux (and related) + browser.
 
 Summary
 -------
@@ -15,17 +17,18 @@ sound is produced by a virtual machine that executes small bytecode to produce
 the audio; however, by now the internal virtual machine has been heavily
 rewritten and extended. It is actually extended so much that you will never fit
 all the features at the same time in a 4k intro, but a fairly capable synthesis
-engine can already be fitted in 600 bytes (compressed), with another few hundred
-bytes for the patch and pattern data.
+engine can already be fitted in 600 bytes (386, compressed), with another few
+hundred bytes for the patch and pattern data.
 
 Sointu consists of two core elements:
 - A cross-platform synth-tracker app for composing music, written in
   [go](https://golang.org/). The app is not working yet, but a prototype is
   existing. The app exports (will export) the projects as .yml files.
 - A compiler, likewise written in go, which can be invoked from the command line
-  to compile these .yml files into .asm code. The resulting single file .asm can
-  be then compiled by [nasm](https://www.nasm.us/) or
-  [yasm](https://yasm.tortall.net).
+  to compile these .yml files into .asm or .wat code. For x86 platforms, the
+  resulting .asm can be then compiled by [nasm](https://www.nasm.us/) or
+  [yasm](https://yasm.tortall.net). For browsers, the resulting .wat can be
+  compiled by [wat2wasm](https://github.com/WebAssembly/wabt).
 
 Building
 --------
@@ -53,6 +56,13 @@ sointu-compile -o . -arch=386 tests/test_chords.yml
 nasm -f win32 test_chords.asm
 ```
 
+WebAssembly example:
+
+```
+sointu-compile -o . -arch=wasm tests/test_chords.yml
+wat2wasm --enable-bulk-memory test_chords.wat
+```
+
 ### Building and running the tests as executables
 
 Building the [regression tests](tests/) as executables (testing that they work
@@ -140,6 +150,11 @@ and the fix
 Use a newer nightly build of yasm that includes the fix. The linker had placed
 our synth object overlapping with DLL call addresses; very funny stuff to debug.
 
+### Building and running the WebAssembly tests
+
+These are automatically invoked by CTest if [node](https://nodejs.org) and
+[wat2wasm](https://github.com/WebAssembly/wabt) are found in the path.
+
 New features since fork
 -----------------------
   - **Compiler**. Written in go. The input is a .yml file and the output is an
@@ -154,6 +169,8 @@ New features since fork
     changes to get it work, using template macros to change the lines between
     32-bit and 64-bit modes. Mostly, it's as easy as writing {{.AX}} instead of
     eax; the macro {{.AX}} compiles to eax in 32-bit and rax in 64-bit.
+  - **Supports compiling into WebAssembly**. This is a complete reimplementation
+    of the core, written in WebAssembly text format (.wat).
   - **Supports Windows, Linux and MacOS**. On all three 64-bit platforms, all
     tests are passing. Additionally, all tests are passing on windows 32.
   - **New units**. For example: bit-crusher, gain, inverse gain, clip, modulate
@@ -270,10 +287,6 @@ Crazy ideas
     uniforms to shader. A track with two voices, triggering an instrument with a
     single envelope and a slow filter can even be used as a cheap smooth
     interpolation mechanism.
-  - **Support WASM targets with the compiler**. It should not be impossible to
-    reimplement the x86 core with WAT equivalent. It would be nice to make it
-    work (almost) exactly like the x86 version, so one could just track the song
-    with Sointu tools and export the song to WAT using sointu-cli.
   - **Hack deeper into audio sources from the OS**. Speech synthesis, I'm eyeing
     at you.