Re: Creating a coding system

[Eli Zaretskii <eliz@gnu.org>]

> From: David Kastrup <dak@gnu.org>
> Date: Sat, 20 Dec 2014 17:52:29 +0100
> Cc: Andreas Schwab <schwab@linux-m68k.org>, emacs-devel@gnu.org
> 
> >  > I am missing the big picture here in some manner.  Does decoding not
> >  > start from a byte stream but rather from an emacs-utf-8 encoded version
> >  > of a byte stream?
> >
> > Either (see Eli's reply).  But the translation table is an add-on, not
> > part of the bytes-to-character coding system itself.
> 
> Huh.  Then maybe I am not doing this right.  I want to use a "process
> coding system" to efficiently sift through Midi data and leaves some
> useful form (a more versatile form would likely be the Lisp reader
> equivalent of MidiXML).

May I suggest to describe your problem in more detail?  I couldn't
glean that from the snippet that started this thread.  (I know nothing
about Midi.)  Maybe if we knew what is it that you are trying to
accomplish with your coding-system, we could be of more assistance.

> It would seem that Handa-san is currently the only documentation for the
> coding system details Emacs has.  Some more redundancy might be a good
> idea.

We already have that:


  32.10 Coding Systems
  ====================

  When Emacs reads or writes a file, and when Emacs sends text to a
  subprocess or receives text from a subprocess, it normally performs
  character code conversion and end-of-line conversion as specified by a
  particular "coding system".

     How to define a coding system is an arcane matter, and is not
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  documented here.
  ^^^^^^^^^^^^^^^^