LuaDecompy/README.md

# LuaDecompy

An experimental Lua 5.1 dump decompiler (typically dumped using `luac -o <out.luac> <script.lua>`).

You will quickly find that only **extremely** simple scripts are decompiled successfully right now. This is an experimental project and not all opcodes are properly handled for now. If you need a real decompiler I would recommend any of the handful of ones that exist already.

## Why?

Lua has a relatively small instruction set (only 38 different opcodes!). This makes it pretty feasible for a weekend decompiler project. (real) Decompilers are extremely complex pieces of software, so being able to write a simpler one helps show the theory without *much* of the headache.

## Example usage

```sh
> cat example.lua && luac5.1 -o example.luac example.lua
i = 0

while i < 10 do
    print(i)
    i = i + 1
end
> python main.py example.luac
example.luac

==== [[example.lua's constants]] ====

0: [STRING] i
1: [NUMBER] 0.0
2: [NUMBER] 10.0
3: [STRING] print
4: [NUMBER] 1.0

==== [[example.lua's dissassembly]] ====

[  0]      LOADK :   R[0]   K[1]               ; load 0.0 into R[0]
[  1]  SETGLOBAL :   R[0]   K[0]               ; 
[  2]  GETGLOBAL :   R[0]   K[0]               ; 
[  3]         LT :   R[0]   R[0]   K[2]        ; 
[  4]        JMP :   R[0]      7               ; 
[  5]  GETGLOBAL :   R[0]   K[3]               ; 
[  6]  GETGLOBAL :   R[1]   K[0]               ; 
[  7]       CALL :   R[0]      2      1        ; 
[  8]  GETGLOBAL :   R[0]   K[0]               ; 
[  9]        ADD :   R[0]   R[0]   K[4]        ; 
[ 10]  SETGLOBAL :   R[0]   K[0]               ; 
[ 11]        JMP :   R[0]    -10               ; 
[ 12]     RETURN :   R[0]      1      0        ; 

==== [[example.lua's decompiled source]] ====


i = 0.0
while i < 10.0 do 
    print(i)
    i = (i + 1.0)
end

```