Difference between revisions of "Simcity 2000 Special Edition"

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(Beginning documentation of SC2 format. Whew!)
(Corrected error in compression algorithm explanation, added style to segment types table.)
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::: byte {<span style="color:red">x</span>} - Raw, uncompressed data
 
::: byte {<span style="color:red">x</span>} - Raw, uncompressed data
 
:: <span style="color:blue">// If 129 <= <span style="color:red">x</span> <= 255:</span>
 
:: <span style="color:blue">// If 129 <= <span style="color:red">x</span> <= 255:</span>
::: byte {1} - This byte repeats <span style="color:red">x</span> times.
+
::: byte {1} - The following byte repeats <span style="color:red">x</span>-127 times.
  
 
: <span style="color:blue">// Repeat for the rest of this segment's data length.</span>
 
: <span style="color:blue">// Repeat for the rest of this segment's data length.</span>
Line 156: Line 156:
  
 
'''Additional notes on segment types:'''
 
'''Additional notes on segment types:'''
{|
+
{| class="wikitable"
 +
!ID
 +
!style="text-align:left;"| Comments
 
|-
 
|-
 
|CNAM
 
|CNAM
 
|The name of the city, uncompressed, and also optional it seems. When it's present, the length byte is a number 0 to 31, with that many bytes of city name. It's padded to 32 bytes with zeroes.
 
|The name of the city, uncompressed, and also optional it seems. When it's present, the length byte is a number 0 to 31, with that many bytes of city name. It's padded to 32 bytes with zeroes.
 
|}
 
|}

Revision as of 21:08, 17 February 2016

Choose archive extension:

IDX + DAT


Format Specifications

// for each file

uint32 {4}   - ID
uint32 {4}   - File Offset


MultiEx BMS Script

Not written yet

Notes and Comments

  • The *.idx file contains the directory, the *.dat file contains the file data



Compatible Programs


SC2

Format Specifications

// HEADER

char {4} - Chunk Type ID ('FORM')
int32 {4} - Total count of bytes in file minus first 8 in the header
char {4} - File type (always 'SCDH' for SimCity 2000)

// Begin segments/nested chunks. For each nested chunk:

// Segment header

char {4} - Segment type
int32 {4} - Byte count of this segment minus this header (-8 bytes)

// Segment data, begin sub-segment bytes (let x = the byte's value)

byte {1}
// If 1 <= x <= 127:
byte {x} - Raw, uncompressed data
// If 129 <= x <= 255:
byte {1} - The following byte repeats x-127 times.
// Repeat for the rest of this segment's data length.

Notes and Comments

  • This is the file format in which cities are stored. See the IFF page on Wikipedia (linked above) for more information on the format, although it is essentially a generic container file format.
  • All of this information is thanks to the research done by David Moews, with a document here.
  • After the header, the rest of the file is made up of chunks containing an 8 byte header followed by its data. Almost all segment data is compressed using a run-length algorithm. Specifically:
    • The compressed data is a series of two kinds of chunks
    • In the first kind, the first byte equates to an integer 1 to 127. This means the byte is counting how many data bytes follow.
    • In the second kind, the first byte equates to an integer 129 to 255. If you subtract 127 from it, you end up with a count of how many times the following byte is repeated.
    • Chunks with a first byte of 0 or 128 never seem to occur.
    • Therefor, the maximum size of an uncompressed sub-chunk can be 127 bytes.

Segment Types

  • The following table is a list of segment types in the order they typically appear. Unless noted, they are compressed using the above algorithm. The lengths given are their uncompressed lengths.
Seg. type Length (bytes)
CNAM 32 (Uncompressed)
MISC 4800
ALTM 32768 (Uncompressed)
XTER 16384
XBLD 16384
XZON 16384
XUND 16384
XTXT 16384
XLAB 6400
XMIC 1200
XTHG 480
XBIT 16384
XTRF 4096
XPLT 4096
XVAL 4096
XCRM 4096
XPLC 1024
XFIR 1024
XPOP 1024
XROG 1024
XGRP 3328

Additional notes on segment types:

ID Comments
CNAM The name of the city, uncompressed, and also optional it seems. When it's present, the length byte is a number 0 to 31, with that many bytes of city name. It's padded to 32 bytes with zeroes.