Better docs and tests

Author: commonkestrel

README.md

@@ -1,11 +1,24 @@
 # Fateful
 ![GitHub Workflow Status (with event)](https://img.shields.io/github/actions/workflow/status/commonkestrel/fateful/rust.yml)
 
-Fateful is a CLI tool for working with my custom CPU, F8ful.
-Very much a work in progress.
+Fateful is a CLI tool foring with my custom CPU, F8ful.
+It contains an emulator and an assembler.
+Fateful can be installed through [cargo](https://github.com/rust-lang/cargo) via `cargo install --git https://github.com/commonkestrel/fateful`.
 
-# Peripherals
+## Assembler
 
+The assembler can be used with the `fateful asm` or `fateful assemble` command to assembler f8ful assembly into f8ful machine code.
+The input and output are both optional, and default to `stdin` and `stdout` respectively.
+
+### Instructions
+
+There are sixteen instructions in f8ful assembly.
+
+## Emulator
+
+## Tests
+
+## Peripherals
 Peripherals are a way to extend the emulator,
 simulating a memory-mapped peripheral.
 This is through the use of dynamic library loading,

examples/fib.asm

@@ -1,4 +1,9 @@
 /// calculates the 8th fibonacci number and leaves the result in register D
+/// 
+/// a: 0x0D
+/// b: 0x15
+/// c: 0x00
+/// d: 0x15
 
 @org 0x0000
 @define COUNT 7

src/assembler/macros.asm

@@ -320,3 +320,7 @@
 }
 
 @macro use(%label:ident|label) {}
+
+@macro shl (%r:reg) {
+    add %r, %r
+}