Secret Files: Tunguska (Demo) SPR - Revision history

imported>Ikskoks: /* Games */

2021-04-04T14:24:58Z

Games

← Older revision	Revision as of 14:24, 4 April 2021
(No difference)

imported>Ikskoks: /* Games */

2021-04-04T14:24:58Z

Games

← Older revision		Revision as of 14:24, 4 April 2021
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	=== Games ===		=== Games ===
	* [[Secret Files: Tunguska (Demo)]] [[SPR\|*.spr]]		* [[Secret Files: Tunguska (Demo)]] [[SPR\|*.spr]]
			<br><br>

	~~{{GRAFPageFooter}}~~

	[[Category:Platform PC\|Secret Files: Tunguska (Demo) SPR]] [[Category:Complete Almost Done\|Secret Files: Tunguska (Demo) SPR]] [[Category:CE Both\|Secret Files: Tunguska (Demo) SPR]]		[[Category:Platform PC\|Secret Files: Tunguska (Demo) SPR]]
			[[Category:Complete Almost Done\|Secret Files: Tunguska (Demo) SPR]]
			[[Category:CE Both\|Secret Files: Tunguska (Demo) SPR]]
			[[Category:XOR encryption]]
	[[Category:File Format]]		[[Category:File Format]]

imported>Ikskoks at 11:49, 21 January 2021

2021-01-21T11:49:19Z

← Older revision	Revision as of 11:49, 21 January 2021
(No difference)

imported>Ikskoks at 11:49, 21 January 2021

2021-01-21T11:49:19Z

← Older revision		Revision as of 11:49, 21 January 2021
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	[[Category:Platform PC\|Secret Files: Tunguska (Demo) SPR]] [[Category:Complete Almost Done\|Secret Files: Tunguska (Demo) SPR]] [[Category:CE Both\|Secret Files: Tunguska (Demo) SPR]]		[[Category:Platform PC\|Secret Files: Tunguska (Demo) SPR]] [[Category:Complete Almost Done\|Secret Files: Tunguska (Demo) SPR]] [[Category:CE Both\|Secret Files: Tunguska (Demo) SPR]]
			[[Category:File Format]]

imported>Dinoguy1000: GRAFPageMisc cleanup

2011-11-01T21:44:16Z

GRAFPageMisc cleanup

← Older revision	Revision as of 21:44, 1 November 2011
(No difference)

imported>Dinoguy1000: GRAFPageMisc cleanup

2011-11-01T21:44:16Z

GRAFPageMisc cleanup

← Older revision		Revision as of 21:44, 1 November 2011
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	== SPR ==		== SPR ==
	{{GRAFPageMisc~~\|date_posted=14:47, 6 August 2007 (CDT)~~}}		{{GRAFPageMisc}}

	=== Format Specifications ===		=== Format Specifications ===

imported>DenizOezmen: updated compression info

2007-10-03T21:14:25Z

updated compression info

← Older revision	Revision as of 21:14, 3 October 2007
(No difference)

imported>DenizOezmen: updated compression info

2007-10-03T21:14:25Z

updated compression info

← Older revision		Revision as of 21:14, 3 October 2007
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	uint32 {4}   - {{Unknown}}<br>		uint32 {4}   - {{Unknown}}<br>
	uint32 {4}   - {{Unknown}}<br>		uint32 {4}   - {{Unknown}}<br>
	~~uint32~~ {4}   - Number of strings<br>		int32 {4}    - Number of strings<br>
	~~uint32~~ {4}   - String table offset<br>		int32 {4}    - String table offset<br>
	~~uint32~~ {4}   - String table size<br>		int32 {4}    - String table size<br>
	~~uint32~~ {4}   - Number of files<br>		int32 {4}    - Number of files<br>
	~~uint32~~ {4}   - File table offset<br>		int32 {4}    - File table offset<br>
	~~uint32~~ {4}   - File table size<br>		int32 {4}    - File table size<br>
	uint32 {4}   - {{Unknown}}<br>		uint32 {4}   - {{Unknown}}<br>
	~~uint32~~ {4}   - Number of directories<br>		int32 {4}    - Number of directories<br>
	~~uint32~~ {4}   - Directory table offset<br>		int32 {4}    - Directory table offset<br>
	~~uint32~~ {4}   - Directory table size<br>		int32 {4}    - Directory table size<br>
	byte {x}     - File data<br>		byte {x}     - File data<br>
	{{BlockDescription\|// string table data (encrypted)}}<br>		{{BlockDescription\|// string table data (encrypted)}}<br>
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	{{BlockDescription\|// directory table data (encrypted)}}<br>		{{BlockDescription\|// directory table data (encrypted)}}<br>
	:{{BlockDescription\|// for each directory}}<br>		:{{BlockDescription\|// for each directory}}<br>
	::~~uint32~~ {4}   - Directory name {{InlineComment\|(index into string table)}}<br>		::int32 {4}    - Directory name {{InlineComment\|(index into string table)}}<br>
	::~~uint32~~ {4}   - Parent directory {{InlineComment\|(index into directory table, 0x1effffff for root)}}<br>		::int32 {4}    - Parent directory {{InlineComment\|(index into directory table, 0x1effffff for root)}}<br>
	{{BlockDescription\|// file table data (encrypted)}}<br>		{{BlockDescription\|// file table data (encrypted)}}<br>
	:{{BlockDescription\|// for each file}}<br>		:{{BlockDescription\|// for each file}}<br>
	::~~uint32~~ {4}   - Parent directory {{InlineComment\|(index into directory table)}}<br>		::int32 {4}    - Parent directory {{InlineComment\|(index into directory table, 0x1effffff for root)}}<br>
	::~~uint32~~ {4}   - Name prefix {{InlineComment\|(index into string table)}}<br>		::int32 {4}    - Name prefix {{InlineComment\|(index into string table)}}<br>
	::~~uint32~~ {4}   - Name suffix {{InlineComment\|(index into string table)}}<br>		::int32 {4}    - Name suffix {{InlineComment\|(index into string table)}}<br>
	::uint32 {4}   - CRC32 of uncompressed data<br>		::uint32 {4}   - CRC32 of uncompressed data {{InlineComment\|(might not be set, zero in that case)}}<br>
	::{{BlockDescription\|// file date (as Windows _SYSTEMTIME type)}}<br>		::{{BlockDescription\|// file date (as Windows _SYSTEMTIME type)}}<br>
	:::uint16 {2}   - Year<br>		:::uint16 {2}   - Year<br>
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	:::uint16 {2}   - Second<br>		:::uint16 {2}   - Second<br>
	:::uint16 {2}   - Millisecond<br>		:::uint16 {2}   - Millisecond<br>
	::~~uint32~~ {4}   - Size of uncompressed data<br>		::int32 {4}    - Size of uncompressed data<br>
	::~~uint32~~ {4}   - Compression header offset {{InlineComment\|(0xffffffff if file ~~uncompressed~~)}}<br>		::int32 {4}    - Compression header offset {{InlineComment\|(0xffffffff if file is not compressed)}}<br>
	::~~uint32~~ {4}   - Compression header size {{InlineComment\|(0 if file ~~uncompressed~~)}}<br>		::int32 {4}    - Compression header size {{InlineComment\|(zero if file is not compressed)}}<br>
	::~~uint32~~ {4}   - File data offset<br>		::int32 {4}    - File data offset<br>
	::~~uint32~~ {4}   - File data size<br>		::int32 {4}    - File data size<br>
	}}		}}

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	==== Data decompression ====		==== Data decompression ====

	In cases of compressed file data, the compression header offset and size values will be set to appropriate values. Note that the data offset value will then point to the compressed data block~~, which is prepended by a uint32 containing the uncompressed size. (This size value is not present if the data is not compressed~~.) The compression header itself might look different for various compression techniques, but only one is known to be used in the game.		In cases of compressed file data, the compression header offset and size values will be set to appropriate values. Note that the data offset value will then point to the compressed data block. The compression header itself might look different for various compression techniques, but only one is known to be used in the game's archives.

	===== SLZX =====		===== SLZX =====

	The compression header of the SLZX method is constructed by a four-char identifier (SLZX) followed by a ~~uint32~~ value storing the uncompressed data size. (Please note that this results in three distinct places where the uncompressed size can be found: The file table entry, the SLZX compression header and the beginning of the compressed data block.)		The compression header of the SLZX method is constructed by a four-char identifier (SLZX) followed by a int32 value storing the uncompressed data size. The compressed data block is prepended by an int32, also containing the uncompressed size. (Please note that this results in three distinct places where the uncompressed size can be found: The file table entry, the SLZX compression header and the beginning of the compressed data block.)

	The compression technique itself is a variant of the common [[LZSS]] in the following sense:		The compression technique itself is a variant of the common [[LZSS]] in the following sense:

imported>DenizOezmen: added format description

2007-08-06T19:47:16Z

added format description

← Older revision	Revision as of 19:47, 6 August 2007
(No difference)

imported>DenizOezmen: added format description

2007-08-06T19:47:16Z

added format description

New page

{{GRAFPageHeader}}

== SPR ==
{{GRAFPageMisc|date_posted=14:47, 6 August 2007 (CDT)}}

=== Format Specifications ===
{{GRAFPageFormat|1=
char {4}     - ID {{Constant|(SPCD)}} 
uint32 {4}   - {{Unknown}} 
uint32 {4}   - {{Unknown}} 
uint32 {4}   - Decryption key seed 
uint32 {4}   - {{Unknown}} 
uint32 {4}   - {{Unknown}} 
uint32 {4}   - Number of strings 
uint32 {4}   - String table offset 
uint32 {4}   - String table size 
uint32 {4}   - Number of files 
uint32 {4}   - File table offset 
uint32 {4}   - File table size 
uint32 {4}   - {{Unknown}} 
uint32 {4}   - Number of directories 
uint32 {4}   - Directory table offset 
uint32 {4}   - Directory table size 
byte {x}     - File data 
{{BlockDescription|// string table data (encrypted)}} 
:{{BlockDescription|// for each string}} 
::uint16 {2}   - String length 
:{{BlockDescription|// for each string}} 
::char {x}     - String data 
{{BlockDescription|// directory table data (encrypted)}} 
:{{BlockDescription|// for each directory}} 
::uint32 {4}   - Directory name {{InlineComment|(index into string table)}} 
::uint32 {4}   - Parent directory {{InlineComment|(index into directory table, 0x1effffff for root)}} 
{{BlockDescription|// file table data (encrypted)}} 
:{{BlockDescription|// for each file}} 
::uint32 {4}   - Parent directory {{InlineComment|(index into directory table)}} 
::uint32 {4}   - Name prefix {{InlineComment|(index into string table)}} 
::uint32 {4}   - Name suffix {{InlineComment|(index into string table)}} 
::uint32 {4}   - CRC32 of uncompressed data 
::{{BlockDescription|// file date (as Windows _SYSTEMTIME type)}} 
:::uint16 {2}   - Year 
:::uint16 {2}   - Month 
:::uint16 {2}   - Day of week 
:::uint16 {2}   - Day 
:::uint16 {2}   - Hour 
:::uint16 {2}   - Minute 
:::uint16 {2}   - Second 
:::uint16 {2}   - Millisecond 
::uint32 {4}   - Size of uncompressed data 
::uint32 {4}   - Compression header offset {{InlineComment|(0xffffffff if file uncompressed)}} 
::uint32 {4}   - Compression header size {{InlineComment|(0 if file uncompressed)}} 
::uint32 {4}   - File data offset 
::uint32 {4}   - File data size 
}}

=== Notes and Comments ===

==== Table decryption ====

Each of the three structure tables has been xor-encrypted. The decryption depends on the seed value given in the header as well as a partly fixed key domain value. The decryption key will change for each byte in the buffer (depending on the previously seen bytes), as shown in this pseudo code:

 
<tt>
KeyDomain := 0xbebe2 * Seed; 
Key := ((Seed shl 8) or ((not Seed) and 0xff)); 
 
for i := 0 to Length(Data) - 1 do 
begin
:Key := (Key * Key) mod KeyDomain; 
:Buffer[i] := Buffer[i] xor (Key and 0xff); 
:Key := Key + Buffer[i] + 1; 
end;
</tt>
 

==== Data decompression ====

In cases of compressed file data, the compression header offset and size values will be set to appropriate values. Note that the data offset value will then point to the compressed data block, which is prepended by a uint32 containing the uncompressed size. (This size value is not present if the data is not compressed.) The compression header itself might look different for various compression techniques, but only one is known to be used in the game.

===== SLZX =====

The compression header of the SLZX method is constructed by a four-char identifier (SLZX) followed by a uint32 value storing the uncompressed data size. (Please note that this results in three distinct places where the uncompressed size can be found: The file table entry, the SLZX compression header and the beginning of the compressed data block.)

The compression technique itself is a variant of the common [[LZSS]] in the following sense:
* The interpretation of the bit flags is reversed (0 indicates a literal copy, while 1 indicates a buffer reference).
* An offset/length pair is given by a little-endian uint16 value. The uppermost five bits store the length, while the lower 11 bits contain the offset value. After each such offset/length pair there follows exactly one additional literal character.
* The history buffer (2048 bytes in size) is not circular, but slides along the output. All offsets are absolute buffer references. (Please note that the buffer "window" only starts sliding forward as soon as 2048 bytes of data have been output.)

=== MultiEx BMS Script ===
{{NoBMSScript}}

=== Supported by Programs ===
* [http://gamefileformats.the-underdogs.info/files/tunguskaexplorer11.zip Geheimakte Tunguska Explorer ]
* [http://oezmen.eu/gameresources/ SPRExt]

=== Links ===
None

=== Games ===
* [[Secret Files: Tunguska (Demo)]] [[SPR|*.spr]]

{{GRAFPageFooter}}

[[Category:Platform PC|Secret Files: Tunguska (Demo) SPR]] [[Category:Complete Almost Done|Secret Files: Tunguska (Demo) SPR]] [[Category:CE Both|Secret Files: Tunguska (Demo) SPR]]