feat: add support for big-endian systems and big-/little-endian interop #36
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Before this change, fsst did not even work on big-endian systems: ``` $ ./binary /usr/share/dict/words words.fsst Compressed 2486824 bytes into 3239956 bytes ==> 130% $ ./binary -d words.fsst words.dec Decompressed 3239953 bytes into 2486824 bytes ==> 76% $ head /usr/share/dict/words A a aa aal aalii aam Aani aardvark aardwolf Aaron $ head words.dec A v wo Ao Aoc Aoc Aot ``` With this change, it works correctly on big-endian systems and delivers the exact same result as on little-endian systems. Furthermore, the symbol tables produced by `fsst_export()` will always use little-endian version headers, and `fsst_import()` will always expect little-endian version headers, regardless of which system the code is running on. This enables symbol table exchange between big- and little-endian systems, as the remainder of the symbol table is byte-order-agnostic. The change is fully backwards-compatible. On little-endian systems, the code should behave exactly as before. On big-endian systems, the numeric 64-bit value of a symbol will be swapped as needed and will always be stored as little-endian. There is certainly some overhead in doing this, but it is much better than not being able to use fsst at all on big-endian systems.
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Before this change, fsst did not even work on big-endian systems:
With this change, it works correctly on big-endian systems and delivers the exact same result as on little-endian systems. Furthermore, the symbol tables produced by
fsst_export()will always use little-endian version headers, andfsst_import()will always expect little-endian version headers, regardless of which system the code is running on. This enables symbol table exchange between big- and little-endian systems, as the remainder of the symbol table is byte-order-agnostic.The change is fully backwards-compatible.
On little-endian systems, the code should behave exactly as before. On big-endian systems, the numeric 64-bit value of a symbol will be swapped as needed and will always be stored as little-endian. There is certainly some overhead in doing this, but it is much better than not being able to use fsst at all on big-endian systems.