gettimeofday.hsc

gettimeofday.hsc

{-# LANGUAGE ForeignFunctionInterface #-}

#include <sys/time.h>

module Main where

import Prelude
import Foreign.C.Error (throwErrnoIfMinus1_)
import Foreign.C.Types
import Foreign.Marshal.Alloc (allocaBytes)
import Foreign.Ptr (Ptr, nullPtr)
import Foreign.Storable

getPOSIXTime :: IO (CTime, CSUSeconds)
getPOSIXTime = allocaBytes #{size struct timeval} $ \ ptv -> do
    throwErrnoIfMinus1_ "gettimeofday" $ gettimeofday ptv nullPtr
    sec <- #{peek struct timeval, tv_sec} ptv :: IO CTime
    usec <- #{peek struct timeval, tv_usec} ptv :: IO CSUSeconds
    return (sec, usec)

foreign import ccall unsafe "time.h gettimeofday"
    gettimeofday :: Ptr () -> Ptr () -> IO CInt

main :: IO ()
main = do
    putStrLn $ "CTime: " ++ show (sizeOf (undefined :: CTime))
    putStrLn $ "CUSeconds: " ++ show (sizeOf (undefined :: CUSeconds))
    putStrLn $ "CSUSeconds: " ++ show (sizeOf (undefined :: CSUSeconds))
    putStrLn $ "timeval: " ++ show (#{size struct timeval} :: Int)
    putStrLn $ "tv_sec: " ++ show (#{size ((struct timeval *)NULL)->tv_sec} :: Int)
    putStrLn $ "tv_usec: " ++ show (#{size ((struct timeval *)NULL)->tv_usec} :: Int)
    getPOSIXTime >>= print