The MessageTrans module
From: RMokady@acorn.co.uk (Ran Mokady)
Subject: Re: MessageTrans
Date: 13 Mar 91 16:31:35 GMT
As requested here is the MessageTrans documentation.
Overview
--------
This document describes the SWI interface to the MessageTrans module, which
provides message translation services, and the format of the message files
that it uses.
SWI MessageTrans_FileInfo
In R1 -> filename
Out R0 = flag word:
bit 0 set => file is held in memory (can be accessed directly)
bits 1..31 reserved (ignore them)
R2 = size of buffer required to hold file
if R0 bit 0 set, the buffer is not required for read-only access
SWI MessageTrans_OpenFile
In R0 -> 4-word data structure
must be held in the RMA if R2=0 on entry
R1 -> filename, held in the RMA if R2=0 on entry
(NOTE: FILENAME MUST REMAIN UNCHANGED FOR THE DURATION OG THE FILE BEING OPEN)
R2 -> buffer to hold file data
0 => allocate some space in the RMA,
or use the file directly if possible
Error: "Message file already open" if R0 points to a structure
already known to MessageTrans (ie. already open).
An application may decide that it would like to buffer the file in
its own workspace (rather than the RMA) if it needs to be loaded, or
use the file directly if it is already in memory. To do this:
SYS "MessageTrans_FileInfo",,filename$ TO flags%,,size%
IF flags% AND 1 THEN buffer%=0 ELSE buffer%=FNalloc(size%)
SYS "OS_Module",6,,,17+LENfilename$ TO ,,filedesc%
$(filedesc%+16)=filename$
SYS "MessageTrans_OpenFile",filedesc%,filedesc%+16,buffer%
where FNalloc() allocates a buffer of a given size, by using the
Wimp_SlotSize or "END=" command. Note that in fact the filename and
file descriptor only need to be in the RMA if R2=0 on entry to
MessageTrans_OpenFile.
Note: If R2=0 on entry to this SWI, and the application uses direct
pointers into the file (rather than copying the messages out) or
uses MessageTrans_MakeMenus, it should also trap
Service_MessageFileClosed, in case the file is unloaded.
SWI MessageTrans_Lookup
In R0 -> 4-word data structure passed to MessageTrans_OpenFile
R1 -> token, terminated by any char <= 32, or "," or ")"
or token:default message terminated by 0 char.
R2 -> buffer to hold result (0 => don't copy it)
R3 = buffer size (if R2 non-0)
R4 -> parameter 0 (0 => don't substitute for "%0")
R5 -> parameter 1 (0 => don't substitute for "%1")
R6 -> parameter 2 (0 => don't substitute for "%2")
R7 -> parameter 3 (0 => don't substitute for "%3")
Out R1 -> terminator of token
R2 -> result string (read-only with no sustitution if R2=0 on entry)
R3 = size of result before terminator
(terminator = 10 if R2=0 on entry, else 0)
This SWI allows a message token to be translated into a string, with
optional parameter substitution.
The application must have called MessageTrans_OpenFile beforehand in
order to use this SWI, although you can still call it if the file has
been automatically closed by the system, because it will automatically
re-open it as well.
If the message token does not match, the error "Message token not found"
is returned unless the token was followed by ":default value", in which
case the default value is returned (I.E. either copied to the buffer or
pointed at). This error is also given if the value to be returned is on
the last line of the file, and does not have a terminating CHR$(10).
See the "File format" section for further details.
SWI MessageTrans_MakeMenus
In R0 -> 4-word data structure passed to MessageTrans_OpenFile
R1 -> menu definition (see below)
R2 -> RAM buffer to hold menu structure
R3 = size of RAM buffer
Out [R1..] = menu data
R3 = bytes remaining in buffer (should be 0 if you got it right)
"Buffer overflow" error if buffer is too small
Menu structure:
+0 (n) Token for menu title, terminated by any char <= 32, or "," or ")"
null => no more menus, otherwise:
+n (1) menu title foreground and frame colour
(1) menu title background colour
(1) menu work area foreground colour
(1) menu work area background colour
(1) height of menu items
(1) gap between items
Menu items:
(n) Token for menu item, terminated by any char <= 32, or "," or ")"
Word-align to here (addr := (addr+3) AND (NOT 3))
(4) Menu flags (bit 7 set => last item)
(4) Offset from RAM menu start to RAM submenu start
0 => no submenu
(4) Icon flags
This SWI allows a menu structure to be set up from a structure
containing references to tokens, and sets up menu widths. Parameter
substitution is not allowed.
The application must have called MessageTrans_OpenFile beforehand in
order to use this SWI, although you can still call it if the file has
been automatically closed by the system, because it will automatically
re-open it as well.
If the icon flags have bit 8 clear (ie. they are not indirected), the
message text for the icon will be read into the 12-byte block that forms
the icon data, otherwise the icon data will be set up to point to the
message text inside the file data. In the latter case they are
read-only.
If the menu item flags bit 2 is set (writeable) and the icon is
indirected, the 3 words of the icondata in the RAM buffer are assumed to
have already been set up by the calling program. The result of looking
up the message token is copied into the buffer indicated by the first
word of the icon data (truncated if it gets bigger than the buffer size
indicated in [icondata,#8]).
SWI MessageTrans_CloseFile
In R0 -> 4-word data structure passed to MessageTrans_OpenFile
Service_MessageFileClosed
In R0 -> 4-word data structure passed to MessageTrans_OpenFile
Out If the application recognises the value of R0 passed in, and it has
any direct pointers into the message data that it relates to, it
should re-initialise itself by calling MessageTrans_OpenFile again
to re-open the file, and recache its pointers. If it has used
MessageTrans_MakeMenus, it should call Wimp_GetMenuState to see if
its menu tree it open, and delete it using Wimp_CreateMenu(-1) if
so.
This service call is only ever issued if the file is not held in the
user's own buffer. It tells the application that its file data has been
thrown away, for example if the file is held inside a module which is
then reloaded.
It is only necessary to trap this service call if direct pointers into
the file data are being used. Otherwise, the MessageTrans module will
make a note in the file descriptor that the file has been closed, and
simply re-open it when MessageTrans_Lookup or MessageTrans_MakeMenus is
next called on that file.
It is recommended that applications that cannot trap service calls do not
use direct pointers into the file data (eg. indirected icons with
MessageTrans_MakeMenus). They can still use such indirected icons, if
they provide a buffer pointer in R2 on entry to MessageTrans_OpenFile (so
that the message file data is copied into the buffer).
Service_Reset
Since MessageTrans does not close message files on a soft reset,
applications that do not wish their message files to be open once they
leave the desktop should call MessageTrans_CloseFile for all their open
files at this point. However, it is perfectly legal for message files to
be left open over soft reset.
File format
-----------
Message files contain a series of one-line token / value pairs, terminated
by character 10 (linefeed).
::= { }*
::= | "#" |
::= { "/" | }* :
::= { }*
::= |
::= any character > " " except ",", ")", ":", "?" or "/"
::= "?" (matches any character)
::= { }*
::= any character except
::= character code 10
::= { | "%0" | "%1" | "%2" | "%3" | "%%" }*
Note that the spaces in the above description are purely to improve
readability - in fact spaces are significant inside tokens, so should only
really appear in and .
Alternative tokens are separated by "/" or . If any of the alternative
tokens before the next ":" match the supplied token, the value after the
next ":" up to the following is returned. The "?" character in a token
in the file matches any character in the supplied match token. Case is
significant.
If R2 is not 0 on entry to MessageTrans_Lookup, "%0", "%1", "%2" and "%3"
are subsitituted with the parameters supplied in R4..R7, except where the
relevant register is 0, in which case the text is left alone. "%%" is
converted to "%" - otherwise if no parameter substitution occurs the text is
left alone. No other substitution is performed on the string.
For example:
# This is an example message file
TOK1:This value is obtained only for "TOK1".
TOK2
TOK3/TOK4:This value is obtained for "TOK2","TOK3" or "TOK4"
TOK?:This value is obtained for "TOK"
ANOTHER:Parameter in R4 = %0, parameter in R5 = %1.
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