Re: [Haskell-cafe] Detecting system endianness
On Thu, 2008-12-18 at 22:35 -0500, wren ng thornton wrote: > In a similar vein, is there already a function available to give the > size of Word in bytes? Or should I write the usual Ptr conversion tricks > to figure it out? How about this: (`div` 8) $ ceiling $ logBase 2 $ fromIntegral (maxBound :: Word) Could write an integral log_2 function to make it nicer :) - George signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Detecting system endianness
Foreign.Storable.sizeOf wren: > In a similar vein, is there already a function available to give the > size of Word in bytes? Or should I write the usual Ptr conversion tricks > to figure it out? > > > > Holger Siegel wrote: > >On Thursday 18 December 2008 13:40:47 Ryan Ingram wrote: > >>Actually, this is probably safer: > >> > >>import Foreign.Marshal.Alloc > >>import Foreign.Ptr > >>import Foreign.Storable > >>import Data.Word > >>import System.IO.Unsafe > >> > >>endianCheck = unsafePerformIO $ alloca $ \p -> poke p (0x01020304 :: > >>Word32) >> peek (castPtr p :: Ptr Word8) > >> > >>littleEndian = endianCheck == 4 > >>bigEndian = endianCheck == 1 > >> > >> -- ryan > > > > > >Using modules Data.Binary, Data.Binary.Put and Data.Word, you can define > > > > littleEndian = (decode $ runPut $ putWord16host 42 :: Word8) == 42 > > > >Under the hood, it also uses peek and poke, but it looks a bit more > >functional. > > > -- > Live well, > ~wren > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Detecting system endianness
In a similar vein, is there already a function available to give the size of Word in bytes? Or should I write the usual Ptr conversion tricks to figure it out? Holger Siegel wrote: On Thursday 18 December 2008 13:40:47 Ryan Ingram wrote: Actually, this is probably safer: import Foreign.Marshal.Alloc import Foreign.Ptr import Foreign.Storable import Data.Word import System.IO.Unsafe endianCheck = unsafePerformIO $ alloca $ \p -> poke p (0x01020304 :: Word32) >> peek (castPtr p :: Ptr Word8) littleEndian = endianCheck == 4 bigEndian = endianCheck == 1 -- ryan Using modules Data.Binary, Data.Binary.Put and Data.Word, you can define littleEndian = (decode $ runPut $ putWord16host 42 :: Word8) == 42 Under the hood, it also uses peek and poke, but it looks a bit more functional. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Detecting system endianness
On Thursday 18 December 2008 13:40:47 Ryan Ingram wrote: > Actually, this is probably safer: > > import Foreign.Marshal.Alloc > import Foreign.Ptr > import Foreign.Storable > import Data.Word > import System.IO.Unsafe > > endianCheck = unsafePerformIO $ alloca $ \p -> poke p (0x01020304 :: > Word32) >> peek (castPtr p :: Ptr Word8) > > littleEndian = endianCheck == 4 > bigEndian = endianCheck == 1 > > -- ryan > > On Thu, Dec 18, 2008 at 4:33 AM, Ryan Ingram wrote: > > I think something like this might work: > > > > Prelude GHC.Exts GHC.Word> let W64# x = 0x10002 in W32# > > (unsafeCoerce# x) 2 > > > > You should get 1 for big-endian and 2 for little-endian. > > > > (Disclaimer: not particularily well-tested.) Using modules Data.Binary, Data.Binary.Put and Data.Word, you can define littleEndian = (decode $ runPut $ putWord16host 42 :: Word8) == 42 Under the hood, it also uses peek and poke, but it looks a bit more functional. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Detecting system endianness
Actually, this is probably safer: import Foreign.Marshal.Alloc import Foreign.Ptr import Foreign.Storable import Data.Word import System.IO.Unsafe endianCheck = unsafePerformIO $ alloca $ \p -> poke p (0x01020304 :: Word32) >> peek (castPtr p :: Ptr Word8) littleEndian = endianCheck == 4 bigEndian = endianCheck == 1 -- ryan On Thu, Dec 18, 2008 at 4:33 AM, Ryan Ingram wrote: > I think something like this might work: > > Prelude GHC.Exts GHC.Word> let W64# x = 0x10002 in W32# (unsafeCoerce# x) > 2 > > You should get 1 for big-endian and 2 for little-endian. > > (Disclaimer: not particularily well-tested.) > > -- ryan > > On Thu, Dec 18, 2008 at 3:27 AM, Mauricio wrote: >> Hi, >> >> Is there some way I can check the endianness >> of the machine my haskell code is running in? >> >> Thanks, >> Maurício >> >> ___ >> Haskell-Cafe mailing list >> Haskell-Cafe@haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> > ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Detecting system endianness
I think something like this might work: Prelude GHC.Exts GHC.Word> let W64# x = 0x10002 in W32# (unsafeCoerce# x) 2 You should get 1 for big-endian and 2 for little-endian. (Disclaimer: not particularily well-tested.) -- ryan On Thu, Dec 18, 2008 at 3:27 AM, Mauricio wrote: > Hi, > > Is there some way I can check the endianness > of the machine my haskell code is running in? > > Thanks, > Maurício > > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Detecting system endianness
Hi, Is there some way I can check the endianness of the machine my haskell code is running in? Thanks, Maurício ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
