[OLPC-devel] Compression

[Mitch Bradley]

I have code for the gzip "inflate" algorithm (as used in gzip and pkzip) 
that is suitable for embedded use.

I started with Mark Adler's (not-copyrighted) code from INFO-Zip and 
modified it to run in an embedded environment.  It decompresses from a 
memory array to RAM with no external dependencies, and it accesses all 
of its working data relative to a base address pointer, so it is 
position-independent.  That makes it possible to use the same compiled 
image in many different circumstances.  It can be used directly from ROM 
in order to decompress other parts of the ROM, or copied to RAM for 
faster execution, without having to worry about relocation dances.

FirmWorks has used this code for many years on many different 
processors, so it is known to work well.

The size (on x86) is:

wmb at bdco:~/obp/tools$ cc -c -O inflate.c
wmb at bdco:~/obp/tools$ size inflate.o
   text    data     bss     dec     hex filename
   5435       0       0    5435    153b inflate.o