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content/posts/os/2024-08-11.md

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+title = 'Os Devlog: Lisp Compiler'
+date = 2024-09-08T12:00:00+02:00
+categories = ["os"]
+tags = ["lowlevel", "lisp", "compiler"]
+summary = "LISP :3"
+draft = true
++++
+
+## Introduction
+In my previous article I wrote about my [os](https://forgejo.vanten-s.com/vanten-s/os). 
+In this article I will explore the [compiler I have made for the system](https://forgejo.vanten-s.com/vanten-s/lisp-8bit).
+
+## Goals for the compiler
+Goals are important for getting stuff done. With this compiler I want to:
+- Implement a simple LISP language 
+- Compile to a format that my OS supports
+- Functions
+- Variables
+- Loops
+- If statements
+- First-class functions
+
+## AST
+
+For the program
+```lisp
+(+ 1 (+
+   a b ))
+```
+The AST looks like this:
+```text
+   /  \
+  +  /  \
+    1  /  \
+     /  \ NIL
+    +  /  \
+      a  /  \
+        b   NIL
+```
+
+## Compilation
+My lisp-implementation is heavily stack-based, and only uses registers when using instructions that need them. 
+
+For example, a + function could compiler to this:
+```asm
+pop eax
+pop ebx
+add eax, ebx
+push eax
+```
+