Shafa is a free and open-source program made for Lossless files' compression written in C (2020/21).
It is OS independent and some modules are multithread executed if running on Windows or POSIX-compliant (allowing pthreads).

Uses two algorithms for compression:

• RLE
• Shannon Fano with blocks of length 1 (K=1).

For RLE's decompression a .freq file is needed along with the .rle file.
For Shannon Fano's decompression a .cod file is needed along with .shaf.
(All these files are generated by the program)

• F ( RLE compression and Frequencies calculation )
• T ( Codes calculation using Shannon-Fano's algorithm )
• C ( Shannon-Fano compression )
• D ( RLE and Shannon-Fano decompression )

gcc -o shafa $(find ./src -name '*.c' -or -name '*.h') -O3 -Wno-format -pthread

gcc -o shafa src/*.c src/*.h src/*/*.c src/*/*.h src/*/*/*.c src/*/*/*.h -O3 -Wno-format

Open terminal where the created executable shafa is located and type the following:

Windows:

• shafa.exe <file> <options>

*NIX:

• ./shafa <file> <options>

-m <module>      :  Executes respective module (Can be executed more than one module if possible)
-b <K/m/M>       :  Blocks size for compression (default: K)
-c <r/f>         :  Forces execution (r -> RLE's compress | f -> Original file's frequencies)
-d <s/r>         :  Only executes a specific decompression (s -> Shannon-Fano's algorithm | r -> RLE's algorithm)
--no-multithread :  Disables multithread 

• K = 640 KiB
• m = 8 MiB
• M = 64 MiB

Note: Multithread was only implemented in modules C and D (the ones that cost the most)