> net#arf:$.a500.RiscOS+.doc.MsgTrans
Author: Neil Raine
Status: Description of module in RISC OS+
History:
2-Nov-89 0.01 First draft.
3-Nov-89 0.02 Name changed to MessageTrans, parameters altered.
6-Nov-89 0.03 Assembler header file section added.
6-Nov-89 0.04 Added bit about Service_Reset
7-Nov-89 0.05 Fixed typo in BASIC example of MessageTrans_OpenFile
8-Nov-89 0.06 Updated docn of OpenFile and Lookup
22-Nov-89 0.07 Updated docn of MessageTrans_MakeMenus
7-Aug-90 0.08 Removed references to DeskFS/ResourceFS
This document describes the SWI interface to the MessageTrans module, which provides message translation services, and the format of the message files that it uses.
SWI MessageTrans_FileInfo
In R1 -> filename
Out R0 = flag word:
bit 0 set => file is held in memory (can be accessed directly)
bits 1..31 reserved (ignore them)
R2 = size of buffer required to hold file
if R0 bit 0 set, the buffer is not required for read-only access
SWI MessageTrans_OpenFile
In R0 -> 4-word data structure
must be held in the RMA if R2=0 on entry
R1 -> filename, held in the RMA if R2=0 on entry
R2 -> buffer to hold file data
0 => allocate some space in the RMA,
or use the file directly if possible
Error: "Message file already open" if R0 points to a structure
already known to MessageTrans (ie. already open).
An application may decide that it would like to buffer the file in
its own workspace (rather than the RMA) if it needs to be loaded, or
use the file directly if it is already in memory. To do this:
SYS "MessageTrans_FileInfo",,filename$ 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_LoadFile
R1 -> token, terminated by any char <= 32, or "," or ")"
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.
See the "File format" section for further details.
SWI MessageTrans_GSLookup
In R0 -> 4-word data structure passed to MessageTrans_LoadFile
R1 -> token, terminated by 0, 10 or 13, or "token:default"
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 R0,R1 -> preserved.
R2 -> result string (read-only with no parameter substitution if R2=0 on entry)
R3 = size of result before terminator (character 10 if R2=0 on entry, else 0)
Same as MessageTrans_Lookup, only string is GSTransed before you get
it back, but after the parameters are substituted This needs an
intermidiate buffer, and so will fail if one cannot be allocated
from the RMA.
Calling this SWI with R2=0 is exactly equivalent to
MessageTrans_Lookup with R2=0
SWI MessageTrans_ErrorLookup
In R0 -> Error block (Word aligned) containing error number , token, terminated by 0 or error number , "token:default" terminated by 0.
R1 -> 4-word data structure passed to MessageTrans_LoadFile
R2 -> buffer to hold result (0 => Use internal buffer)
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 R0 -> Error buffer used
V Set
This is like MessageTrans_Lookup, but is used for error messages, the error number is copied into the dest. buffer and then a lookup is done on the token and the result put after the error number in the dest. buffer.
If R2 is 0 on entry, MessageTrans will use one of its internal buffers for the result. There are 3 buffers for foreground processes and 3 for calls made from within IRQ processes. MessageTrans will cycle between these buffers.
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.
Message files contain a series of one-line token / value pairs, terminated by character 10 (linefeed).
<file> ::= { <line> }*
<line> ::= <tokline> | "#" <comment><nl> | <nl>
<tokline> ::= <token> { "/"<token> | <nl><token> }* : <value><nl>
<token> ::= <tokchar> { <tokchar> }*
<tokchar> ::= <char> | <wildcard>
<char> ::= any character > " " except ",", ")", ":", "?" or "/"
<wildcard> ::= "?" (matches any character)
<comment> ::= { <anychar> }*
<anychar> ::= any character except <nl>
<nl> ::= character code 10
<value> ::= { <anychar> | "%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 <comment> and <value>.
Alternative tokens are separated by "/" or <nl>. If any of the alternative tokens before the next ":" match the supplied token, the value after the next ":" up to the following <nl> 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<not 1,2,3 or 4>"
ANOTHER:Parameter in R4 = %0, parameter in R5 = %1.
If the message token does not match, the error "Message token not found" is returned. 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).
There are two header files for the MessageTrans module:
Hdr.MsgTrans ; SWI numbers and names
Hdr.MsgMenus ; macros for use with MessageTrans_MakeMenus
The latter file defines two macros for setting up the data structures for use with MessageTrans_MakeMenus. It is used as follows:
GET &.Hdr.WimpSpace
GET &.Hdr.MsgTrans
GET &.Hdr.MsgMenus
...
^ 0, R12 ; set up workspace (R12-relative)
m_start # 0 m_main # m_headersize + 3 * mi_size m_sub # m_headersize + 3 * mi_size m_end # 0
...
ADR r0, filedesc ; open message file
ADR r1, filename
SWI XMessageTrans_OpenFile
BVS Error
...
ADR r0, filedesc ; construct menus
ADR r1, rom_menus
ADR r2, m_start
MOV r3, m_end-m_start
SWI XMessageTrans_MakeMenus
BVS Error_close_messagefile
...
ADR r0, filedesc ; close message file
SWI XMessageTrans_CloseFile
...
rom_menus
m_main Menu T00 ; T00 = token for title of main menu mo_01 Item M01 ; M01 = token for item 0 of main menu mo_02 Item M02,m_sub ; submenu pointer to m_submo_03 Item M03
m_sub Menu T02
mo_12 Item M12 ; M12 = token for item 1 of submenu 2mo_22 Item M22
DCB 0 ; terminator of menu structure
ALIGN
Error_close_messagefile
MOV r1, r0
MOV r2, pc
ADR r0, filedesc
SWI XMessageTrans_CloseFile
MOVVC r0, r1
TEQVCP r2, #0
Error
<report error and abort>
The 'Menu' macro sets up the header for the menu, and remembers the name of the menu being defined. It also calculates how many Items will follow, based on the size of the buffer reserved for the RAM menu.
The 'Item' macro sets up the data for a menu item. It allows a submenu to be referenced, and automatically converts this into an offset from the current menu header to the required submenu. It also allows the item to be specified as writeable, have a dotted line underneath it, and be indirected (the default) or not. See Hdr.MsgMenus for further details.