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'''NatsumeGB compression''' is the compression algorithm used in numerous Game Boy Natsume games, namely, at least Telefang and Medarot.  It is a modified implementation of the LZ77 algorithm, which works by referencing previously decompressed data using length-distance pairs.  [http://en.wikipedia.org/wiki/LZ77_and_LZ78_%28algorithms%29 Wikipedia] has a good description of the algorithm.
Malias compression is the compression used in multiple Smilesoft games, namely, at least Telefang and Medarot 1.  It is a modified implementation of the LZ77 algorithm, which works by referencing previously decompressed data using length-distance pairs.  [http://en.wikipedia.org/wiki/LZ77_and_LZ78_%28algorithms%29 Wikipedia] has a good description of the algorithm.


NatsumeGB was formerly called Malias compression after [http://s15.zetaboards.com/Tulunk_Village/topic/515644/ Malias], the person who wrote the first decompresser.
Malias compression is named after [http://s15.zetaboards.com/Tulunk_Village/topic/515644/ Malias], the person who wrote the first decompresser.


Implementation of the NatsumeGB compression in pseudocode:
Implementation of the Malias compression in pseudocode:


<pre>compressed = readbyte()
<pre>compressed = readbyte()
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     while bytes < total:            # bytes is number of bytes decompressed
     while bytes < total:            # bytes is number of bytes decompressed
         modes = readshort()        # Contains modes for the next 10 bytes
         modes = readshort()        # Contains modes for the next 10 bytes
         for mode in bits(modes):
         do 0x10 times:
             if mode == 0x1:         # Copy mode
            modes = modes / 2
             if carry:               # Copy mode
                 loc = -(readshort() & 0x7ff)
                 loc = -(readshort() & 0x7ff)
                 num = lastbyte >> 3 & 0x1f + 0x03
                 num = lastbyte >> 3 & 0x1f + 0x03
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             else:                  # Insert mode
             else:                  # Insert mode
                 data += readbyte()</pre>
                 data += readbyte()</pre>
== Games that use the compression ==
* Keitai Denjuu Telefang
* Medarot 1
* Medarot 2
* Medarot 3
* Medarot 4 (assumed)
* Medarot 5 (assumed)
* Croc 2
== Decompression tools ==
== Decompression tools ==
* [http://s15.zetaboards.com/Tulunk_Village/topic/515644/ Malias' Telefang Tools] can decompress and recompress the graphics with ease, provided locations.
* [http://s15.zetaboards.com/Tulunk_Village/topic/515644/ Malias' Telefang Tools] can decompress and recompress the graphics with ease, provided locations.
* [https://github.com/Sanky/romhacking/blob/master/telefang/punika.py punika] is a simple implementation in Python which decompresses all compressed graphics at once, working off tables in the ROM.
* [https://github.com/Sanky/romhacking/blob/master/telefang/punika.py punika] is a simple implementation in Python which decompresses all compressed graphics at once, working off tables in the ROM.
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