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LHA
LHarc, a precursor to the LHA file utility, became one of the standard file
compression/extraction utility in Japan despite its
slowness. I am also pleased that some overseas users have taken to using this
tool.
I, however, have continued on my research for a new compression
algorithm even after releasing LHarc to the public. The fruit of my two years of research is incorporated in the new utility, LHA which I would now like to make
public.
Differences between LHA and LHarc:
Improvements:
- Higher compression. LHA offers a higher compression rate than LHarc especially when compressing large files. On the other hand, compression rate is worse for files smaller than few hundred bytes.
- Faster file extraction. Extraction algorithm was changed to static Huffman algorith from dynamic Huffman algorithm to decrease file extraction
time. Nevertheless, compression time did not decrease as much as I expected.
Degradation:
- Increased memory usage. LHA requires more memory. Use caution when executing LHA from another program or in a child process. When LHA detects memory
shortage, it will try to continue by decreasing compression rate.
- Only upward compatible with LHarc. Files compressed by LHA can not be extracted by
LHarc.
However, files compressed by LHarc may be extracted by LHA.
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Русский текст
