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Add comment to the mysterious order of the + 1 - 1 in printHashBytes32

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This commit is contained in:
John Ericson 2019-03-10 13:09:45 -04:00
parent 9bbe54a03b
commit ecf4d991f9
1 changed files with 4 additions and 1 deletions
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hnix-store-core/src/System/Nix/Internal/Hash.hs
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@ -125,7 +125,10 @@ newtype Digest (a :: HashAlgorithm) = Digest
printHashBytes32 :: BS.ByteString -> T.Text
printHashBytes32 c = T.pack $ concatMap char32 [nChar - 1, nChar - 2 .. 0]
where
-- The base32 encoding is 8/5's as long as the base256 digest
-- The base32 encoding is 8/5's as long as the base256 digest. This `+ 1`
-- `- 1` business is a bit odd, but has always been used in C++ since the
-- base32 truncation was added in was first added in
-- d58a11e019813902b6c4547ca61a127938b2cc20.
nChar = fromIntegral $ ((BS.length c * 8 - 1) `div` 5) + 1
char32 :: Integer -> [Char]