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From: bcking@io.UUCP (Christine King x4426)
Newsgroups: comp.windows.x
Subject: X Fonts: 2Byte vs. 16Bit
Keywords: font,byte order,2byte
Message-ID: <1681@io.UUCP>
Date: 2 Aug 90 15:00:45 GMT
Distribution: comp
Organization: Interleaf Inc, Cambridge, MA
Lines: 41

I'm having a problem with 2byte fonts in X, and I hope somebody can
help.  We are an application (Interleaf) that has to run on various
kinds of clients and servers, some of which have "Motorola" byte-order
and some "VAX" byte-order.  The important difference for this problem
is the representation of a short int: Motorola's are like 00 41, where
the 00 is the high-order byte but the lower address; VAX's are like 41
00.

  (I think I have that right.  If not, I'm sure I'll get flamed.
  Anyway, the two are the reverse of each other, which is what matters
  here.)

For X 2byte fonts, we use arrays of "short" to represent strings of
character codes.  In the Motorola case, for a particular font that has
an "A" in position 0041, the "A" is displayed.  In the VAX case, I
have to swap the bytes of the code to get the "A".  This is all as
described in Scheifler/Gettys/Newman "X Window System".

Howevermuch of a Pain-in-the-Neck this swapping is, I accept it
because it's documented.  But: Scheifler/Gettys/Newman also mention
"16bit fonts" in several places, which seem to be a different thing
from "2byte fonts".

  Do 16-bit fonts really exist in X?

  Are they (in the VAX case) differently indexed than 2-byte fonts?

  Are the BDF descriptions different from a 2byte font?

  Could I use the same code (no swapping), and the same BDF fontfiles
for Motorola and for VAX?

Note that it is a client-side application problem to get the
byte-order correct for a 2byte font.  For a 16bit font, however, I
think it would be a client-side X-implementation problem.  Surely the
server need make no distinction between a 2byte and a 16bit font,
particularly since there is no difference for a Motorola server.


-- 
		--Christine King (bcking@ileaf.com)