1 files changed, 20 insertions, 0 deletions

diff --git a/Data/OpenPGP/Internal.hs b/Data/OpenPGP/Internal.hs
new file mode 100644
index 0000000..b2bd506
--- /dev/null
+++ b/Data/OpenPGP/Internal.hs
@@ -0,0 +1,20 @@
+module Data.OpenPGP.Internal where
+
+import Data.Word
+import Data.Bits
+
+decode_s2k_count :: Word8 -> Word32
+decode_s2k_count c =  (16 + (fromIntegral c .&. 15)) `shiftL`
+        ((fromIntegral c `shiftR` 4) + 6)
+
+encode_s2k_count :: Word32 -> Word8
+encode_s2k_count iterations
+        | iterations >= 65011712 = 255
+        | decode_s2k_count result < iterations = result+1
+        | otherwise = result
+        where
+        result = fromIntegral $ (fromIntegral c `shiftL` 4) .|. (count - 16)
+        (count, c) = encode_s2k_count' (iterations `shiftR` 6) (0::Word8)
+        encode_s2k_count' count c
+                | count < 32 = (count, c)
+                | otherwise = encode_s2k_count' (count `shiftR` 1) (c+1)