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OS/2 2.0 Information Presentation Facility (IPF) Data Format - version 2
----------------------------------------------------------------------- -
*** introduction to version 1 ***
Having become extremely frustrated by VIEW.EXE's penchant for windows
that come and go, without even opening large enough to see everything
in them, I thought I'd try to turn .INF files into something more
conventional. While I don't have code to offer, I can tell you what I
learned about .INF format--it was enough to produce more-or-less
readable more-or-less plaintext from .INFs.
I offer this in the hope that somebody will give the community a
really nice, tasteful, convenient, doesn't-use-too-much-screen-real-estate
.INF browser to replace VIEW.EXE.
All of this was developed by looking at .INF files without any
documentation of the format except what VIEW.EXE showed for a
particular feature.
I don't have a lot of personal interest in refining this document with
additional escape sequences, etc., but I would be happy to correspond
with someone who wanted to fill in the details, or to clarify anything
that may be confusing. If someone could point us to an official document
describing the format that would be most helpful.
-- Carl Hauser (chauser.parc@xerox.com)
*** introduction to version 2 ***
The original document contained most of the real tricky stuff in the file
format (especially the compression algorithm) so going on from there was
mainly a task of creating lots of help files using the IPFC and the
decompiling them again to see what came out.
I fixed a few minor bugs in the description of the header which was
extended to describe the entire structure I believe to be the header
(because variable data starts afterwards).
A number of escape codes have also been added and the descriptions of
others have been refined. There are still a lot of question marks about
the format, but this description already allows disassembling the text
into ASCII form in a fairly true-to-life format (including indentations
etc.).
Further research should go into the way multiple windows are handled
(I didn't work on that because I have never required multiple window
displays in my help files and therefore am not familiar with the concepts).
Font usage and graphics linking could also use some more fiddling around.
-- Marcus Groeber (marcusg@ph-cip.uni-koeln.de - Fidonet 2:243/8605.1)
*** introduction to version 3 ***
Just a bit of an update and flesh out ;-)
-- Peter Childs (pjchilds@apanix.apana.org.au)
*** Version 4 ****
Further additions as found while writing NewView
-- Aaron Lawrence
**** Types ****
All numeric quantities are least-significant-byte first in the file
(little-endian).
bit1 1 bit boolean \ used only for explaining
int4 4 bit unsigned integer / packed structures
char8 8 bit character (ASCII more-or-less)
int8 8 bit unsigned integer
int16 16 bit unsigned integer
int32 32 bit unsigned integer
**** The File Header ****
Starting at file offset 0 the following structure can overlay the file
to provide some starting values:
{
int16 ID; // ID magic word (5348h = "HS")
int8 unknown1; // unknown purpose, could be third letter of ID
int8 flags; // probably a flag word...
// bit 0: set if INF style file
// bit 4: set if HLP style file
// patching this byte allows reading HLP files
// using the VIEW command, while help files
// seem to work with INF settings here as well.
int16 hdrsize; // total size of header
int16 unknown2; // unknown purpose
int16 ntoc; // 16 bit number of entries in the tocarray
int32 tocstrtablestart; // 32 bit file offset of the start of the
// toc entries (this is redundant info;
// the individual offsets are stored starting
// at tocstart)
int32 tocstrlen; // number of bytes in file occupied by the
// table-of-contents entries
int32 tocstart; // 32 bit file offset of the start of tocarray
int16 nres; // number of panels with ressource numbers
int32 resstart; // 32 bit file offset of ressource number table
int16 nname; // number of panels with textual name
int32 namestart; // 32 bit file offset to panel name table
int16 nindex; // number of index entries
int32 indexstart; // 32 bit file offset to index table
int32 indexlen; // size of index table
int8 unknown3[10]; // unknown purpose
int32 searchstart; // 32 bit file offset of full text search table
int32 searchlen; // size of full text search table
int16 nslots; // number of "slots"
int32 slotsstart; // file offset of the slots array
int32 dictlen; // number of bytes occupied by the "dictionary"
int16 ndict; // number of entries in the dictionary
int32 dictstart; // file offset of the start of the dictionary
int32 imgstart; // file offset of image data
int8 unknown4; // unknown purpose
int32 nlsstart; // 32 bit file offset of NLS table
int32 nlslen; // size of NLS table
int32 extstart; // 32 bit file offset of extended data block
int8 unknown5[12]; // unknown purpose
char8 title[48]; // ASCII title of database
}
**** The table of contents entries ****
Beginning at each file offset, tocentrystart[i]:
{
int8 len; // length of the entry including this byte (but not including extended data?)
int8 flags; // flag byte, description folows (MSB first)
// bit7 haschildren; // following nodes are a higher level
// bit6 hidden; // this entry doesn't appear in VIEW.EXE's
// presentation of the toc
// bit5 extended; // extended entry format
// bit4 // ??
// int4 level; // nesting level
int8 ntocslots; // number of "slots" occupied by the text for
// this toc entry
}
if the "extended" bit is not 1, this is immediately followed by
{
int16 tocslots[ntocslots]; // indices of the slots that make up
// the article for this entry
char8 title[]; // the remainder of the tocentry
// until len bytes have been used [not
// zero terminated]
}
if extended is 1 there are intervening bytes that describe
the kind, size and position of the window in which to display the
article. First, there are two flag bytes:
{
int8 w1;
// bit 3: Window controls are specified
// bit 2: Viewport
// bit 1: Size is specified.
// bit 0: Position is specified.
int8 w2;
// bit 3:
// bit 2: Group is specified.
// bit 1
// bit 0: Clear (all windows before display)
}
Then the following optional fields may appear, as specified by w1:
Origin ( 5 bytes )
{
int8 Flags;
// bits 4-7: X position type
// bits 0-3: Y position type
int16 XPosition; // meaning depends on type
int16 YPosition;
}
Position types are:
0 = absolute character
1 = relative %
2 = absolute pixel
3 = absolute points
For these types, the position is simply a number.
If one of the positions is not specified then the type will be 0
and the value will be -1 (65535)
4 = dynamic
For this type the position is one of the following values:
1: left
2: right
4: top;
8: bottom
16: center.
Size ( 5 bytes )
{
int8 Flags;
// bits 4-7: Width type
// bits 0-3: Height type
int16 Width;
int16 Height;
}
Width/height type are same as position types, above, except that dynamic is not used.
Window controls ( 2 bytes )
0, 112 means everything is turned off.
8, 103 means no scroll bars IIRC
Group ( 2 bytes )
{
int16 GroupNumber;
}
GroupNumber is basically a 'frame' or window number.
Here's a C code fragment for computing the number of bytes to skip
int bytestoskip = 0;
if (w1 & 0x8) { bytestoskip += 2 };
if (w1 & 0x1) { bytestoskip += 5 };
if (w1 & 0x2) { bytestoskip += 5 };
if (w2 & 0x4) { bytestoskip += 2 };
skip over bytestoskip bytes (after w2) and find the tocslots and title
as in the non-extended case.
**** The table of contents array ****
Beginning at file offset tocstart, this structure can overlay the
file:
{
int32 tocentrystart[ntoc]; // array of file offsets of
// tocentries (above)
}
**** The Slots array ****
Beginning at file offset slotsstart (provided by the file header) find
{
int32 slots[nslots]; // file offset of the article
// corresponding to this slot
}
**** The Dictionary ****
Beginning at file offset dictstart (provided by the file header) and
continuing until ndict entries have been read (and dictlen bytes have
been consumed from the file) find a sequence of length-preceeded
strings. Note that the length includes the length byte (not Pascal
compatible!). Build a table mapping i to the ith string.
{
char8* strings[ndict];
}
**** The Article entries ****
Beginning at file offset slots[i] the following structure can overlay
the file:
{
int8 stuff; // ?? [always seen 0]
int32 localdictpos; // file offset of the local dictionary
int8 nlocaldict; // number of entries in the local dict
int16 ntext; // number of bytes in the text
int8 text[ntext]; // encoded text of the article
}
**** The Local dictionary ****
Beginning at file position localdictpos (for each article) there is an
array:
{
int16 localwords[nlocaldict];
}
**** The Text ****
The text for an article then consists of words obtained by referencing
strings[localwords[text[i]]] for i in (0..ntext), with the following
exceptions. If text[i] is greater than nlocaldict it means
0xfa => end-of-paragraph, sets spacing to TRUE if not in monospace
0xfb => [unknown]
0xfc => spacing = !spacing
0xfd => line break (outside an example: ".br",
sets spacing to TRUE if not in a
monospace example)
0xfe => space
0xff => escape sequence // see below
When spacing is true, each word needs a space put after it. When
false, the words are abutted and spaces are supplied using 0xfe or the
dictionary. Examples are entered and left with 0xff escape sequences.
The variable "spacing" is initially (start of every article slot) TRUE.
**** 0xff escape sequences ****
These are used to change fonts, make cross references, enter and leave
examples, etc. The general format is
{
int8 FF; // always equals 0xff
int8 esclen; // length of the sequence (including
// esclen but excluding FF)
int8 escCode; // which escape function
}
escCodes I have partially deciphered are
0x01 => unknown
0x02 or 0x11 => (esclen==3) set left margin.
or 0x12 0x11 always starts a new line. Arguments
{
int8 margin; // in spaces, 0=no margin
}
note: in an IPF source, you must code
:lm margin=256. to reset the left margin.
0x03 => (esclen==3) set right margin. Arguments
{
int8 margin; // in spaces, 1=no margin
}
0x04 => (esclen==3) change style. Arguments
{
int8 style; // 1,2,3: same as :hp#.
// 4,5,6: same as :hp5,6,7.
// 0 returns to plain text
}
0x05 => (esclen varies) beginning of cross
reference. The next two bytes of the
escape sequence are an int16 index of
the tocentrystart array. The
remaining bytes (if any) describe the size,
position and characteristics of the
window created when the
cross-reference is followed by VIEW.
Flag1 bit 7: 'split' window
bit 6: autolink
bit 3: window controls specified
bit 2: viewport
bit 1: target size supplied
bit 0: target position supplied
Flag2 bit 0: ?
bit 1: dependent
bit 2: group supplied
0x06 => unknown
0x07 => (esclen==4) footnote start (:fn. tag). Arguments:
{
int16 toc; // toc entry number of text
}
footnotes end with 0x08
0x08 => (escLen==2) end of cross reference
introduced by escape code 0x05 or 0x07
0x09 => unknown
0x0A => unknown
0x0B => (escLen==2) begin monosp. example. set
spacing to FALSE
0x0C => (escLen==2) end monosp. example. set
spacing to TRUE
0x0D => (escLen==2) special text colors. Arguments:
{
int8 color; // 1,2,3: same as :hp4,8,9.
// 0: default color
}
0x0E => Bitmap.
{
int8 flags;
4: runin flag
3: fit (scale) to window
2: align center
1: align right
0: always set?
int32 bitmapStartOffset;
}
e.g. first bitmap always has offset 0
0x0F => if esclen==5 an inlined cross
reference: the title of the referenced
article becomes part of the text.
This is probably the case even if
esclen is not 5, but I don't know the
decoding. In the case that esclen is
5, I don't know the purpose of the
byte following the escCode, but the
two bytes after that are an int16
index of the tocentrystart array.
0x10 => [special link, reftype=launch]
{
int8 unknown; ?
char launch_string[ esclen - 3 ];
}
0x13 or 0x14 => (esclen==2) Set foreground (0x13)
and background (0x14) color. Arguments:
{
int8 color;
\\ 0 - default
\\ 1 - blue
\\ 2 - red
\\ 3 - ??
\\ 4 - green
\\ 5 - cyan
\\ 6 - yellow
\\ 7 - neutral
}
0x15 => unknown
0x16 => [special link, reftype=inform]
0x17 => hide text (:hide. tag). Arguments:
{
char8 key[]; // key required to show text
}
0x18 => end of hidden text (:ehide.)
0x19 => (esclen==3) change font. Arguments
{
int8 fontTableIndex (?);
}
0x1A => (escLen==3) begin :lines. sequence. set
spacing to FALSE. Arguments
{
int8 alignment; // 1,2,4=left,right,center
}
0x1B => (escLen==2) end :lines. sequence. set
spacing to TRUE
0x1C => (escLen==2) Set left margin to current
position. Margin is reset at end of
paragraph.
0x1F => [special link, reftype=hd database=...]
0x20 => (esclen==4) :ddf. tag. Arguments:
{
int16 res; // value of res attribute
}
The font used in the text is the normal IBM extended character set,
including line graphics and some of the characters below 32.
**** The ressource number array ****
Beginning at file offset resstart, this structure can overlay the
file:
{
int16 res[nres]; // ressource number of panels
int16 toc[nres]; // toc entry number of panel
}
**** The text name array ****
Beginning at file offset namestart, this structure can overlay the
file:
{
int16 name[nres]; // index to panel name in dictionary
int16 toc[nres]; // toc entry number of panel
}
**** The index table ****
Beginning at file offset indexstart, a structure like the following
is stored for each of the nindex words (in alphabetical order).
{
int8 nword; // size of name
int8 level; // ? indent level
// bit 6 set: global entry
// bit 1 set: indent (:i2.)
bit 0 always set?
int8 number of roots; // number of root references following
int16 toc; // toc entry number of panel
char8 word[nword]; // index word [not zero-terminated]
there are n roots following:
int32 synonyms; // 32 bit file offset to start of synonyms referencing this word
}
**** The extended data block ****
Not yet decoded. This block has a size of 64 bytes and contains various
pointers to font names, names of externel databases etc.
**** The full text search table ****
Not yet decoded. This table is supressed when "/S" is specified on
the IPFC command line.
In addition to data in...
RLE:
byte RLEType; // ? always 1?
Then a sequence of blocks, until all data used:
byte Header;
// bits 0-6 are N
// bit 7:
// 0: there are N + 1 repeats of next byte.
// 1: N + 1 blocks of 'as is' data follow.
// except
// value $80 means (?) the next byte contains the data byte,
// and the next 2 bytes after that contain a 16 bit repeat number.
e.g. 04 00 means 5 repeats of 0
83 12 34 56 78 means the literal data 12 34 56 78
80 00 62 01 means $162 repeats of 0
byte DataByte; // with escapes
// bit 7 set means there are actually N+1 (=bits0-6) bytes of data to follow
// 0 means there is a single byte of data to follow (e.g. when the byte > 80)
( optionally ) byte[ N+1 ] data
int16 Number of zeroes to follow
**** Image data ****
Beginning at file offset imgstart, this data is a series of compressed
OS/2 bitmaps.
Each starts with a BITMAPFILEHEADER:
{
int16 usType; // 'bM' for bitmap
int32 cbSize; // total bitmap size including header
// BEFORE compression: not correct in this context
int16 xHotspot; // only for icons/pointers, not relevant here?
int16 yHotspot;
int32 offBits; // offset to the actual bitmap data bits
BITMAPINFOHEADER bmp; // further bitmap data:
int32 cbFix; // length of bitmapinfo header structure (12)
// (including this field)
int16 cx; // bitmap width
int16 cy; // bitmap height
int16 cPlanes; // num bitplanes - always 1 AFAIK
int16 bitCount; // bits per pixel e.g. 4 = 16 colors
RGB palette[ N ]; // 2 ^ bitCount * 3 bytes
bitmapData; // in a special IPF format:
int32 totalLength; // not including this field, but including the next
int16 bitmapSize; // total size of memory required
// for uncompressed bitmap i.e.
// bytes per line rounded up to longword (4byte)
// x rows
// (This info is redundant)
Followed by a series of blocks each up to 64k uncompressed.
Blocks:
int16 dataLength; // length of data following (including data type field)
int8 dataType; // 0 = uncompressed
2 = compressed
data...
Compression is LZW (Lempel Ziv XX?)
}
**** NLS table ****
Not yet decoded. This table contains informations specific to the
language and codepage the document was prepared in. It seems to contain
some bitfields as well that might be used for character classification.
Appendix 1: Some useful translations from IBM Extended ASCII to normal ASCII
One other transformation I had to make was of the character box
characters of the IBM extended ASCII set. These characters appear in strings
in the dicitonary. They are given here in octal together with their translation.
020, 021 => blank seems satisfactory
037 => solid down arrow: used to give direction to
a line in the syntax diagrams
0263 => vertical bar
0264 => left connector: vertical bar with short
horizontal bar extending left from the
center
0277, 0300 => top right or bottom left corner; one is
one, the other is the other and I
can't tell which from my translation
0301 => up connector: horizontal line with vertical
line extending up from the center
0302 => down connector: horizontal line with
vertical line extending down from the
center
0303 => right connector: vertical bar with short
horizontal bar extending right from
the center
0304 => horizontal bar
0305 => cross connector, i.e. looks like + only
slightly larger to connect with
adjacent chars
0331, 0332 => top left or bottom right corner; one is
one, the other is the other and I
can't tell which from my translation
Appendix 2: Style codes for escCode 0x04 and 0x0D
escCode 0x04 implements font changes associated with the :hp# IPF source tag.
:hp1 is italic font
:hp2 is bold font
:hp3 is bold italic font
:hp5 is normal underlined font
:hp6 is italic underlined font
:hp7 is bold underlined font
tags :hp4, :hp8, and :hp9 introduce different colored text which is encoded in
the .inf or .hlp file using escCode 0x0D. On my monitor normal text is dark blue.
:hp4 text is light blue
:hp8 text is red
:hp9 text is magenta
History:
October 22, 1992: version for initial posting (inf01.doc)
July 12, 1993: second version (refer to introduction for changes) (inf02.doc)
July 18, 1993: added appendices to the second version (inf02a.doc)
|