gistfile1.txt

{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE OverloadedStrings #-}

module Main where

import Data.Int ( Int64 )
import Foreign.Ptr ( Ptr, castPtr )
import Foreign.C.String ( CString )
import Foreign.Storable ( peek, peekElemOff )
import Foreign.Marshal.Alloc ( allocaBytes )
import Foreign.Marshal.Array ( advancePtr )
import Foreign.Storable ( sizeOf )
import Data.Word ( Word8 )
import Data.ByteString ( ByteString, useAsCStringLen, packCStringLen )
import Control.Monad ( zipWithM )

foreign import ccall unsafe "botan_zfec_encode" zfec_encode :: Word -> Word -> Ptr Word8 -> Word -> Ptr (Ptr (Ptr Word8)) -> Ptr (Ptr Word) -> IO Int

main :: IO ()
main = do
  let
    input = "These are not word8s"

    k = 1
    n = 3

  allocaBytes (n * sizeOf (undefined :: Ptr (Ptr (Ptr Word8)))) $ \outputBlocksPtr -> do
    allocaBytes (n * sizeOf (undefined :: Ptr (Ptr Word))) $ \outputSizesPtr -> do
      useAsCStringLen input $ \(inputPtr, inputLen) -> do
        outputBlocks :: Ptr (Ptr Word8) <- peek outputBlocksPtr
        outputSizes :: Ptr Word <- peek outputSizesPtr
        print ("Output sizes before", outputSizes)

        result <- zfec_encode k (fromIntegral n) (castPtr inputPtr) (fromIntegral inputLen) outputBlocksPtr outputSizesPtr
        print result

        print ("Output sizes after", outputSizes)

        return ()