first draft on jibniz post

content/assets/theme.css

@@ -90,9 +90,11 @@ a.footnote-ref sup::after  { content: ']' }
 a {
   color: inherit;
   font-weight: 400;
+  text-decoration: none;
+  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.5);
 }
 
-a:hover {text-decoration: underline}
+/* a:hover {text-decoration: underline} */
 
 hr {
   border: none;
@@ -129,6 +131,8 @@ strong {
   margin: 1em 0 0;
 }
 
+#hd a {box-shadow: none}
+
 #hd > section {
   max-width: var(--width);
   margin: 0 auto;
@@ -244,7 +248,11 @@ header.project ul li {
 }
 
 main blockquote {
-  font: 16px serif;
+  border-left: 2px solid var(--darker);
+  margin: 1em 0;
+  padding: 0 1em;
+  opacity: 0.8;
+  line-height: 1.5;
   font-style: italic;
 }
 

content/posts/2021-04-05-jibniz.md

@@ -0,0 +1,82 @@
+---
+title: Introducing jibniz, a web editor for IBNIZ
+description: jibniz, my web editor for IBNIZ, is now feature complete
+draft: true
+---
+
+I found out [my web editor][jibniz] for the [IBNIZ]
+esoteric programming language had been included in the README of the official
+[IBNIZ] repository last february. This motivated me to actually finish the
+implementation and make it feature complete. This post is a quick introduction to
+IBNIZ and explains some of the machinery involved in running IBNIZ programs in a web
+browser.
+
+## IBNIZ
+
+[IBNIZ] is both an esoteric language created by viznut and the VM to run it.
+They are designed for creating audio and video demos with very terse code.
+
+- [Website](https://github.com/viznut/IBNIZ)
+- [Documentation](https://github.com/viznut/IBNIZ)
+
+
+## jibniz
+
+**jibniz** is a project I started around 2017. The goal being to run IBNIZ
+programs interactively in the web browser. Even at the time, there already
+existed a javascript implementation. However I found the performances to be
+lacking and some features were --- and still are --- missing. So I decided to
+make my own implementation as an exercise.
+
+You can try the live editor here: [jibniz editor][jibniz].
+
+### How it works
+
+We could simply interpret the code each time we need to evaluate it. This is
+insufficient and has terrible performances. Therefore, we compile the IBNIZ code
+itself to javascript. That is, we replace each instruction by a piece of
+javascript code that manipulates the stack directly.
+
+### Features and known limitations
+
+Right now, jibniz is *almost* feature-complete. The only missing instruction is
+the sequencial data fetch `G`. I actually have found no code featuring this
+operator, but it makes me a bit sad to not support it.
+
+The reason is quite simple: in javascript, when using typed arrays, the
+endianness is the one of the host computer, most likely little-endian.
+What this means is that if a 32-bit word `0xAABBCCDD` is to be stored in memory,
+the bytes will end up in the following order: `DD CC BB AA`. This is not a
+problem per se, but then there's this paragraph in the official documentation:
+
+> When a program is started, the memory is filled with the contents of the data
+> segment without any alignment.
+
+That is, when raw data is provided at the end of some code, it *should* be put
+as is in the memory of the VM. If we extrapolate, this means that 32-bit words
+given raw by the user would thus be stored as big-endian. Which would lead to
+unexpected results when fetching whole words from memory. Currently, what
+jibniz does is split the raw data segments into 32-bit words, and store them
+using the host endianness. This plays nice with memory instructions like `@`
+that fetch whole words, not so much with `G`, the only instruction that reads a
+custom number of bits from memory.
+
+A possible fix would be to use a `DataView` on the VM memory buffer rather than
+a `Int32Array`, and read whole words by calling `DataView.getByte` 4 times, thus
+ignoring endianness --- or rather being explicit about it.
+
+### Compiling to WASM
+
+Even if performances are decent, I wanted to take a stab at compiling to
+Webassembly early on. Sadly, IBNIZ has a very specific feature that makes it
+hard to produce WASM: the jump instruction `J` can jump *anywhere* in the code,
+depending on the address found on the top of the stack. In practice, I wasn't
+able to find code examples where jump addresses weren't the typical addresses
+left by loop operators such as `X` and `[`, but if we follow the specification,
+it must be allowed.
+
+In WASM however, jumps are *well-structured*. That is, you can only jump to
+previously defined labels, and labels are statically defined at compile-time.
+
+[IBNIZ]: https://github.com/viznut/IBNIZ
+[jibniz]: https://flupe.github.io/jibniz/

content/projects/jibniz/index.markdown

@@ -7,12 +7,14 @@ labels:
   license: MIT
 ---
 
-**jibniz** is a javascript implementation of the IBNIZ virtual machine.
+**jibniz** is a javascript implementation of the [IBNIZ] virtual machine.
-IBNIZ is an esoteric stack-based programming language created by _, in which every
+[IBNIZ] is an esoteric stack-based programming language created by viznut, in which every
 instruction is one character long. The code is intended to be ran for each
 pixel on a 256x256 screen, at every frame --- making it possible to produce
 animations and interactive demos.
 
+[IBNIZ]: http://viznut.fi/ibniz/
+
 ## Limitations
 
 - Currently, this implementation **does not support audio**.

release.nix

@@ -1,6 +1,4 @@
 let
-  compiler = "ghc884";
-  rev  = "b78e08e981a9ad31036fc6c6fb880c1315b4ebea";
   overlay = _: pkgs: {
     haskellPackages = pkgs.haskellPackages.override {
       overrides = self: super: rec {
@@ -8,9 +6,6 @@ let
       };
     };
   };
-  nixpkgs =
+  pkgs = import <nixpkgs> { overlays = [ overlay ]; };
-    import (builtins.fetchTarball {
-      url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
-    }) { overlays = [ overlay ] ; };
 
-in nixpkgs.haskellPackages.callPackage ./site.nix {}
+in pkgs.haskellPackages.callPackage ./site.nix {}

site.cabal

@@ -18,7 +18,7 @@ executable site
                      , Templates
                      , Readings
                      , Route
-  build-depends:       base >= 4.12 && < 5
+  build-depends:       base
                      , filepath
                      , achille
                      , data-default