Messages in this thread |  | | From | "" <> | Subject | Re: [PATCH 1/4] exfat: Simplify exfat_utf8_d_hash() for code points above U+FFFF | Date | Fri, 3 Apr 2020 02:18:15 +0000 |
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> I guess it was designed for 8bit types, not for long (64bit types) and > I'm not sure how effective it is even for 16bit types for which it is > already used.
In partial_name_hash (), when 8bit value or 16bit value is specified, upper 8-12bits tend to be 0.
> So question is, what should we do for either 21bit number (one Unicode > code point = equivalent of UTF-32) or for sequence of 16bit numbers > (UTF-16)?
If you want to get an unbiased hash value by specifying an 8 or 16-bit value, the hash32() function is a good choice. ex1: Prepare by hash32 () function. hash = partial_name_hash (hash32 (val16,32), hash); ex2: Use the hash32() function directly. hash + = hash32 (val16,32);
> partial_name_hash(unsigned long c, unsigned long prevhash) > { > return (prevhash + (c << 4) + (c >> 4)) * 11; > }
Another way may replace partial_name_hash().
return prevhash + hash32(c,32)
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