A simple-ish example

CRC32.hs

module CRC32 (crc32_tab, crc32, crc32String) where

import Data.Bits
import Data.Word
import Data.Char

-- table and sample code derived from
--  http://www.opensource.apple.com/source/xnu/xnu-1456.1.26/bsd/libkern/crc32.c
--  *  COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or
--  *  code or tables extracted from it, as desired without restriction.

crc32_tab :: [Word32]
crc32_tab = [
        0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
        0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
        0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
        0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
        0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
        0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
        0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
        0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
        0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
        0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
        0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
        0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
        0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
        0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
        0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
        0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
        0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
        0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
        0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
        0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
        0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
        0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
        0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
        0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
        0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
        0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
        0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
        0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
        0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
        0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
        0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
        0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
        0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
        0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
        0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
        0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
        0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
        0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
        0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
        0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
        0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
        0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
        0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
  ]

crc32 :: [Word8] -> Word32
crc32 msg = go 0xffffffff msg
  where go crc []     = crc
        go crc (w:ws) = go crc' ws
           where crc' = (crc `shiftR` 8) `xor`
                        (crc32_tab !! fI (fI crc `xor` w))
                 fI x = fromIntegral x

crc32String :: String -> Word32
crc32String = crc32 . map (fromIntegral . ord)

Examples.hs

import Data.Word
import Data.Bits
import Data.Char
import Debug.Trace

import Data.Array.Accelerate hiding (fromIntegral, shiftR, map, zipWith, unzip, replicate, length, maximum, ord, (!!))
import qualified Data.Array.Accelerate as A
import qualified Data.Array.Accelerate.Data.Bits as B
import Data.Array.Accelerate.Interpreter

import CRC32

crc32_one :: Acc (Vector Word32) -> Exp Word32 -> Exp Word8 -> Exp Word32
crc32_one tab crc char
  = (char A.== 0) ?
       ( crc
       , (tab ! index1 (A.fromIntegral (A.fromIntegral crc `B.xor` char)))
             `B.xor`
          crc `B.shiftR` 8
       )


crcAll :: [String] -> Acc (Vector Word32)
crcAll words = all width init_crcs words
  where
    n = length words

    width = maximum (0 : map length words)

    table :: Acc (Vector Word32)
    table = use (fromList (Z:.256) crc32_tab)

    init_crcs :: Acc (Vector Word32)
    init_crcs = fill (index1 (constant n)) (constant 0xffffffff)

    myHead :: String -> (Word8, String)
    myHead []     = (0, [])
    myHead (c:cs) = (fromIntegral (ord c), cs)

    one_iter :: Acc (Vector Word32) -> Acc (Vector Word8)
             -> Acc (Vector Word32)
    one_iter crcs chars = A.zipWith (crc32_one table) crcs chars

    all :: Int -> Acc (Vector Word32) -> [String] -> Acc (Vector Word32)
    all 0 crcs _     = crcs
    all x crcs words = all (x-1) (one_iter crcs chars) tails
      where
      chars = use (fromList (Z:.n) heads)
      (heads, tails) = unzip (map myHead words)

find :: Acc (Vector Word32) -> Acc (Scalar Int)
find arr = A.fold A.max (constant 0) (A.zipWith check arr ixs)
  where check :: Exp Word32 -> Exp Int -> Exp Int
        check x ix = x A.== password_hash ? ( ix, 0 )

        ixs = generate (shape arr) unindex1

password_hash = constant 0x18f8add4 :: Exp Word32

main = do
  s <- readFile "/usr/share/dict/words"
  let ls = lines s
  let [r] = toList $ run $ find $ crcAll ls
  print (ls !! r)