chore: Use unsafe indexing in internal binary functions.

Author: mchav

src/DataFrame/Internal/Binary.hs

@@ -1,18 +1,23 @@
+{-# LANGUAGE BangPatterns #-}
+
 module DataFrame.Internal.Binary where
 
-import Data.Bits
+import Data.Bits (Bits (unsafeShiftL, (.|.)))
+import Data.ByteString (toStrict)
 import qualified Data.ByteString as BS
-import Data.Int
-import Data.Word
+import Data.ByteString.Builder (toLazyByteString, word32LE, word64LE)
+import qualified Data.ByteString.Unsafe as BS
+import Data.Int (Int32)
+import Data.Word (Word32, Word64, Word8)
 
 littleEndianWord32 :: BS.ByteString -> Word32
 littleEndianWord32 bytes
     | len >= 4 =
         assembleWord32
-            (BS.index bytes 0)
-            (BS.index bytes 1)
-            (BS.index bytes 2)
-            (BS.index bytes 3)
+            (BS.unsafeIndex bytes 0)
+            (BS.unsafeIndex bytes 1)
+            (BS.unsafeIndex bytes 2)
+            (BS.unsafeIndex bytes 3)
     | otherwise =
         assembleWord32
             (byteAtOrZero len bytes 0)
@@ -54,37 +59,21 @@ littleEndianInt32 = fromIntegral . littleEndianWord32
 {-# INLINE littleEndianInt32 #-}
 
 word64ToLittleEndian :: Word64 -> BS.ByteString
-word64ToLittleEndian w =
-    BS.pack
-        [ fromIntegral w
-        , fromIntegral (w `unsafeShiftR` 8)
-        , fromIntegral (w `unsafeShiftR` 16)
-        , fromIntegral (w `unsafeShiftR` 24)
-        , fromIntegral (w `unsafeShiftR` 32)
-        , fromIntegral (w `unsafeShiftR` 40)
-        , fromIntegral (w `unsafeShiftR` 48)
-        , fromIntegral (w `unsafeShiftR` 56)
-        ]
+word64ToLittleEndian = toStrict . toLazyByteString . word64LE
 {-# INLINE word64ToLittleEndian #-}
 
 word32ToLittleEndian :: Word32 -> BS.ByteString
-word32ToLittleEndian w =
-    BS.pack
-        [ fromIntegral w
-        , fromIntegral (w `unsafeShiftR` 8)
-        , fromIntegral (w `unsafeShiftR` 16)
-        , fromIntegral (w `unsafeShiftR` 24)
-        ]
+word32ToLittleEndian = toStrict . toLazyByteString . word32LE
 {-# INLINE word32ToLittleEndian #-}
 
 byteAtOrZero :: Int -> BS.ByteString -> Int -> Word8
 byteAtOrZero len bytes i
-    | i >= 0 && i < len = BS.index bytes i
+    | i >= 0 && i < len = BS.unsafeIndex bytes i
     | otherwise = 0
 {-# INLINE byteAtOrZero #-}
 
 assembleWord32 :: Word8 -> Word8 -> Word8 -> Word8 -> Word32
-assembleWord32 b0 b1 b2 b3 =
+assembleWord32 !b0 !b1 !b2 !b3 =
     fromIntegral b0
         .|. (fromIntegral b1 `unsafeShiftL` 8)
         .|. (fromIntegral b2 `unsafeShiftL` 16)
@@ -93,7 +82,7 @@ assembleWord32 b0 b1 b2 b3 =
 
 assembleWord64 ::
     Word8 -> Word8 -> Word8 -> Word8 -> Word8 -> Word8 -> Word8 -> Word8 -> Word64
-assembleWord64 b0 b1 b2 b3 b4 b5 b6 b7 =
+assembleWord64 !b0 !b1 !b2 !b3 !b4 !b5 !b6 !b7 =
     fromIntegral b0
         .|. (fromIntegral b1 `unsafeShiftL` 8)
         .|. (fromIntegral b2 `unsafeShiftL` 16)