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@dpk dpk/gist:4223533

Created Dec 6, 2012
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What would you like to do?
Apple's CFHash algorithm for strings in Ruby
# Why? Why not!
def cfhash string
result = string.length
max = 2 ** 32
string.each_codepoint do |cp|
result = ((result * 257) % max) + cp
end
return (result + (result << (string.length & 31))) % max
end
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dpk commented Dec 6, 2012

This still isn't quite right. For some strings it's correct, for others it's wrong.

(Notably, it will be wrong for strings longer than 96 characters, because that's special-cased in the original algorithm. But I don't need to cover that case for what I'm using this for.)

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