% Copyright (C) 2001, 2004 Ian Lynagh <igloo@earth.li>

% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2, or (at your option)
% any later version.

% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.

% You should have received a copy of the GNU General Public License
% along with this program; see the file COPYING.  If not, write to
% the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
% Boston, MA 02110-1301, USA.

\begin{code}
{-# OPTIONS_GHC -fglasgow-exts -fno-warn-name-shadowing #-}
-- -fglasgow-exts needed for nasty hack below
-- name shadowing disabled because a,b,c,d,e are shadowed loads in step 4
module SHA1 (sha1PS) where

import Autoconf (big_endian)
import FastPackedString (PackedString, unsafeWithInternals,
                         concatPS, packWords, lengthPS)

import Control.Monad (unless)
import Data.Char (intToDigit)
import Data.Bits (xor, (.&.), (.|.), complement, rotateL, shiftL, shiftR)
import Data.Word (Word8, Word32)
import Foreign.Ptr (Ptr, castPtr)
import Foreign.Marshal.Array (advancePtr)
import Foreign.Storable (peek, poke)
import System.IO.Unsafe (unsafePerformIO)

data ABCDE = ABCDE !Word32 !Word32 !Word32 !Word32 !Word32
data XYZ = XYZ !Word32 !Word32 !Word32

sha1PS :: PackedString -> String
sha1PS s = s5
 where s1_2 = sha1_step_1_2_pad_length s
       abcde = sha1_step_3_init
       abcde' = unsafePerformIO
              $ unsafeWithInternals s1_2 (\ptr len ->
                    do let ptr' = castPtr ptr
                       unless big_endian $ fiddle_endianness ptr' len
                       sha1_step_4_main abcde ptr' len)
       s5 = sha1_step_5_display abcde'

fiddle_endianness :: Ptr Word32 -> Int -> IO ()
fiddle_endianness p 0 = p `seq` return ()
fiddle_endianness p n
 = do x <- peek p
      poke p $ shiftL x 24
           .|. shiftL (x .&. 0xff00) 8
           .|. (shiftR x 8 .&. 0xff00)
           .|. shiftR x 24
      fiddle_endianness (p `advancePtr` 1) (n - 4)
\end{code}

sha1_step_1_2_pad_length assumes the length is at most 2^61.
This seems reasonable as the Int used to represent it is normally 32bit,
but obviously could go wrong with large inputs on 64bit machines.
The PackedString library should probably move to Word64s if this is an
issue, though.

\begin{code}
sha1_step_1_2_pad_length :: PackedString -> PackedString
sha1_step_1_2_pad_length s
 = let len = lengthPS s
       num_nuls = (55 - len) `mod` 64
       padding = 128:replicate num_nuls 0
       len_w8s = reverse $ size_split 8 (fromIntegral len*8)
   in concatPS [s, packWords padding, packWords len_w8s]

size_split :: Int -> Integer -> [Word8]
size_split 0 _ = []
size_split p n = fromIntegral d:size_split (p-1) n'
 where (n', d) = divMod n 256

sha1_step_3_init :: ABCDE
sha1_step_3_init = ABCDE 0x67452301 0xefcdab89 0x98badcfe 0x10325476 0xc3d2e1f0
\end{code}

\begin{code}
sha1_step_4_main :: ABCDE -> Ptr Word32 -> Int -> IO ABCDE
sha1_step_4_main abcde _ 0 = return $! abcde
sha1_step_4_main (ABCDE a0@a b0@b c0@c d0@d e0@e) s len
    = do
         (e, b) <- doit f1 0x5a827999 (x 0) a b c d e
         (d, a) <- doit f1 0x5a827999 (x 1) e a b c d
         (c, e) <- doit f1 0x5a827999 (x 2) d e a b c
         (b, d) <- doit f1 0x5a827999 (x 3) c d e a b
         (a, c) <- doit f1 0x5a827999 (x 4) b c d e a
         (e, b) <- doit f1 0x5a827999 (x 5) a b c d e
         (d, a) <- doit f1 0x5a827999 (x 6) e a b c d
         (c, e) <- doit f1 0x5a827999 (x 7) d e a b c
         (b, d) <- doit f1 0x5a827999 (x 8) c d e a b
         (a, c) <- doit f1 0x5a827999 (x 9) b c d e a
         (e, b) <- doit f1 0x5a827999 (x 10) a b c d e
         (d, a) <- doit f1 0x5a827999 (x 11) e a b c d
         (c, e) <- doit f1 0x5a827999 (x 12) d e a b c
         (b, d) <- doit f1 0x5a827999 (x 13) c d e a b
         (a, c) <- doit f1 0x5a827999 (x 14) b c d e a
         (e, b) <- doit f1 0x5a827999 (x 15) a b c d e
         (d, a) <- doit f1 0x5a827999 (m 16) e a b c d
         (c, e) <- doit f1 0x5a827999 (m 17) d e a b c
         (b, d) <- doit f1 0x5a827999 (m 18) c d e a b
         (a, c) <- doit f1 0x5a827999 (m 19) b c d e a
         (e, b) <- doit f2 0x6ed9eba1 (m 20) a b c d e
         (d, a) <- doit f2 0x6ed9eba1 (m 21) e a b c d
         (c, e) <- doit f2 0x6ed9eba1 (m 22) d e a b c
         (b, d) <- doit f2 0x6ed9eba1 (m 23) c d e a b
         (a, c) <- doit f2 0x6ed9eba1 (m 24) b c d e a
         (e, b) <- doit f2 0x6ed9eba1 (m 25) a b c d e
         (d, a) <- doit f2 0x6ed9eba1 (m 26) e a b c d
         (c, e) <- doit f2 0x6ed9eba1 (m 27) d e a b c
         (b, d) <- doit f2 0x6ed9eba1 (m 28) c d e a b
         (a, c) <- doit f2 0x6ed9eba1 (m 29) b c d e a
         (e, b) <- doit f2 0x6ed9eba1 (m 30) a b c d e
         (d, a) <- doit f2 0x6ed9eba1 (m 31) e a b c d
         (c, e) <- doit f2 0x6ed9eba1 (m 32) d e a b c
         (b, d) <- doit f2 0x6ed9eba1 (m 33) c d e a b
         (a, c) <- doit f2 0x6ed9eba1 (m 34) b c d e a
         (e, b) <- doit f2 0x6ed9eba1 (m 35) a b c d e
         (d, a) <- doit f2 0x6ed9eba1 (m 36) e a b c d
         (c, e) <- doit f2 0x6ed9eba1 (m 37) d e a b c
         (b, d) <- doit f2 0x6ed9eba1 (m 38) c d e a b
         (a, c) <- doit f2 0x6ed9eba1 (m 39) b c d e a
         (e, b) <- doit f3 0x8f1bbcdc (m 40) a b c d e
         (d, a) <- doit f3 0x8f1bbcdc (m 41) e a b c d
         (c, e) <- doit f3 0x8f1bbcdc (m 42) d e a b c
         (b, d) <- doit f3 0x8f1bbcdc (m 43) c d e a b
         (a, c) <- doit f3 0x8f1bbcdc (m 44) b c d e a
         (e, b) <- doit f3 0x8f1bbcdc (m 45) a b c d e
         (d, a) <- doit f3 0x8f1bbcdc (m 46) e a b c d
         (c, e) <- doit f3 0x8f1bbcdc (m 47) d e a b c
         (b, d) <- doit f3 0x8f1bbcdc (m 48) c d e a b
         (a, c) <- doit f3 0x8f1bbcdc (m 49) b c d e a
         (e, b) <- doit f3 0x8f1bbcdc (m 50) a b c d e
         (d, a) <- doit f3 0x8f1bbcdc (m 51) e a b c d
         (c, e) <- doit f3 0x8f1bbcdc (m 52) d e a b c
         (b, d) <- doit f3 0x8f1bbcdc (m 53) c d e a b
         (a, c) <- doit f3 0x8f1bbcdc (m 54) b c d e a
         (e, b) <- doit f3 0x8f1bbcdc (m 55) a b c d e
         (d, a) <- doit f3 0x8f1bbcdc (m 56) e a b c d
         (c, e) <- doit f3 0x8f1bbcdc (m 57) d e a b c
         (b, d) <- doit f3 0x8f1bbcdc (m 58) c d e a b
         (a, c) <- doit f3 0x8f1bbcdc (m 59) b c d e a
         (e, b) <- doit f2 0xca62c1d6 (m 60) a b c d e
         (d, a) <- doit f2 0xca62c1d6 (m 61) e a b c d
         (c, e) <- doit f2 0xca62c1d6 (m 62) d e a b c
         (b, d) <- doit f2 0xca62c1d6 (m 63) c d e a b
         (a, c) <- doit f2 0xca62c1d6 (m 64) b c d e a
         (e, b) <- doit f2 0xca62c1d6 (m 65) a b c d e
         (d, a) <- doit f2 0xca62c1d6 (m 66) e a b c d
         (c, e) <- doit f2 0xca62c1d6 (m 67) d e a b c
         (b, d) <- doit f2 0xca62c1d6 (m 68) c d e a b
         (a, c) <- doit f2 0xca62c1d6 (m 69) b c d e a
         (e, b) <- doit f2 0xca62c1d6 (m 70) a b c d e
         (d, a) <- doit f2 0xca62c1d6 (m 71) e a b c d
         (c, e) <- doit f2 0xca62c1d6 (m 72) d e a b c
         (b, d) <- doit f2 0xca62c1d6 (m 73) c d e a b
         (a, c) <- doit f2 0xca62c1d6 (m 74) b c d e a
         (e, b) <- doit f2 0xca62c1d6 (m 75) a b c d e
         (d, a) <- doit f2 0xca62c1d6 (m 76) e a b c d
         (c, e) <- doit f2 0xca62c1d6 (m 77) d e a b c
         (b, d) <- doit f2 0xca62c1d6 (m 78) c d e a b
         (a, c) <- doit f2 0xca62c1d6 (m 79) b c d e a
         let abcde' = ABCDE (a0 + a) (b0 + b) (c0 + c) (d0 + d) (e0 + e)
         sha1_step_4_main abcde' (s `advancePtr` 16) (len - 64)
 where {-# INLINE f1 #-}
       f1 (XYZ x y z) = (x .&. y) .|. ((complement x) .&. z)
       {-# INLINE f2 #-}
       f2 (XYZ x y z) = x `xor` y `xor` z
       {-# INLINE f3 #-}
       f3 (XYZ x y z) = (x .&. y) .|. (x .&. z) .|. (y .&. z)
       {-# INLINE x #-}
       x n = peek (s `advancePtr` n)
       {-# INLINE m #-}
       m n = do let base = s `advancePtr` (n .&. 15)
                x0 <- peek base
                x1 <- peek (s `advancePtr` ((n - 14) .&. 15))
                x2 <- peek (s `advancePtr` ((n - 8) .&. 15))
                x3 <- peek (s `advancePtr` ((n - 3) .&. 15))
                let res = rotateL (x0 `xor` x1 `xor` x2 `xor` x3) 1
                poke base res
                return res
       {-# INLINE doit #-}
       doit f k i a b c d e = a `seq` c `seq`
           do i' <- i
              return (rotateL a 5 + f (XYZ b c d) + e + i' + k,
                      rotateL b 30)

sha1_step_5_display :: ABCDE -> String
sha1_step_5_display (ABCDE a b c d e)
 = concatMap showAsHex [a, b, c, d, e]

showAsHex :: Word32 -> String
showAsHex n = showIt 8 n ""
   where
    showIt :: Int -> Word32 -> String -> String
    showIt 0 _ r = r
    showIt i x r = case quotRem x 16 of
                       (y, z) -> let c = intToDigit (fromIntegral z)
                                 in c `seq` showIt (i-1) y (c:r)

\end{code}