#+TITLE: asm layer

[[file:img/asm.png]]

* Table of Contents                                        :TOC_4_gh:noexport:
 - [[#description][Description]]
 - [[#install][Install]]
     - [[#layer][Layer]]
     - [[#pdfs][PDFs]]
 - [[#key-bindings][Key bindings]]

* Description
This layer adds support for Assembly code. The built-in major mode for
editing assembly code in Emacs is =asm-mode=.

The layer also adds =nasm-mode= for NASM-specific syntax. Although =nasm-mode=
is intended for NASM, it actually works well with other variants of Assembly
in general, and provides Imenu integration so you can jump around with ~SPC s j~.

_Features_:
- Improved syntax highlighting.
- Automatic indentation.
- Auto-completion for symbol in opened buffers.
- Look up documentation for current instruction at cursor.
- Imenu integration.

* Install
*** Layer
To use this configuration layer, add it to your =~/.spacemacs=. You will need to
add =asm= to the existing =dotspacemacs-configuration-layers= list in this
file.

*** PDFs
To look up the x86 instructions, two things are required:

- the =pdftotext= command line tool from Poppler:

#+begin_src sh
  sudo apt-get install poppler-utils
#+end_src

- [[http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html][Intel® 64 and IA-32 Architectures Software Developer Manuals]]. Any PDF that
  contains the full instruction set reference will work, though volume 2 is the
  best choice for x86-lookup.

Then, set =x86-lookup-pdf= to the location of your PDF document (Tip: If you use
Helm as your completion of choice, you can use ~SPC f f~ to navigate to the
file, and press ~C-c i~ to insert the path). For example, something like this:

#+begin_src emacs-lisp
  (setq x86-lookup-pdf "~/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf")
#+end_src

The first time you launch the command, it can take a while for indexing, this
is a one time operation and the result is cached for later use.

* Key bindings

| Key Binding | Description                                        |
|-------------+----------------------------------------------------|
| ~SPC m h h~ | Look up the documentation for instruction at point |
| ~;~         | Insert a comment                                   |

_Note_: Quoted from the docstring of =asm-comment=, the command bound to ~;~:

#+begin_src text
Convert an empty comment to a `larger' kind, or start a new one.
These are the known comment classes:

   1 -- comment to the right of the code (at the comment-column)
   2 -- comment on its own line, indented like code
   3 -- comment on its own line, beginning at the left-most column.

Suggested usage:  while writing your code, trigger asm-comment
repeatedly until you are satisfied with the kind of comment.
#+end_src