Ocar

Ocar is a low-level Assembly transpiler (not a compiler!). With its C-inspired syntax, it aims to provide a more visually appealing way of writing raw assembly.

Now with syntax highlighting!

A previous commit added a VSCode syntax highlighter. To use, run:

code --install-extension ocarlang-0.0.4.vsix

Then press Ctrl+Shift+P and type Developer: Reload Window and press enter. Then, after creating a .ocar file, you should be able to see it syntax highlighted!

Why is it a transpiler and not a compiler?

Technically, it is indeed a compiler. However, because it doesn't provide many features compilers are known to provide (mainly register allocation and recursive expressions), I choose to call it a transpiler because the information for every instruction is pretty much self-contained.

Syntax example

#stdlib entry
#stdlib exit

rtn _start() noret {
  rbx myVar1 = 3;
  rcx myVar2 = 5;
  myVar1 += myVar2;

  @push rax
  @pop rax

  delete myVar1;
  delete myVar2;
  exit();
}

Explanation

1. #stdlib entry includes entry.ocar from the standard library, which defines _start() as the entry point.
2. #stdlib exit includes exit.ocar from the standard library, which allows exit() to exit the program with exit code 0.
3. rtn means routine. It is the language's version of a function.
4. rtn _start() defines a routine called _start(). noret makes it that the transpiler doesn't add a ret at the end of the function, which is not needed for the entry point.
5. rbx myVar1 = 3; and rcx myVar2 = 5; define two variables that take up the registers rbx and rcx respectively. Note that the user manually declares which registers they should take. If any other variable tries to claim those registers without the registers being freed first, the compiler will throw.
6. @push rax and @pop rax are prefixed with @ to signal direct assembly conversion; everything after @ is emitted to assembly directly without any checks.
7. delete myVar1; and delete myVar2; end the lifetime of myVar1 and myVar2, freeing the registers rbx and rcx for possible future use.
8. exit() cals the standard function imported earlier to exit the program.

To-do list

• Add register freeing (e.g. free rax, free rdi)
• Add multiline comments
• Add syscall operation
• Raw register access (e.g. raw rax = 5)
• Variable support for assignment (allow rax a = b;)
• Four operations
  • Implemented three operations; addition, subtraction, and multiplication. Division requires hardcoded registers which doesn't currently work.
• If statements
  • Comparisons
  • Else statements
• Goto and labels
• While loops
• For loops
• Add linking. Probably C-style, because it's easier.
  • Make a standard library
• #noheader option that removes the autogeneration header
• Stack memory acces (e.g. stk[bytecount] varname = 0;, stk[8] myint = 17;)
• Function parameters/arguments
  • Maybe give an optional autopush keyword that finds free spots in the stack and pushes the registers used by parameters into them, then loads them on exit, so users don't have to worry about register data disappearing.
• auto keyword to automatically choose an unused register

Name

Ocar's name is a recursive acronym stnding for OCAR Can't Allocate Registers.