X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=System%2FCPUTime.hsc;h=0ce703e43797208177e40c585916fe57a33c5899;hb=4aeee16da98fecffe2234123fd9654d2e4daa8f6;hp=e5a8a45c41904ef44def88683c97414271b9cb54;hpb=746ef6a7fd71bb1e9ebe3cd107c5f9f79f3b7a68;p=haskell-directory.git

diff --git a/System/CPUTime.hsc b/System/CPUTime.hsc
index e5a8a45..0ce703e 100644
--- a/System/CPUTime.hsc
+++ b/System/CPUTime.hsc
@@ -20,22 +20,25 @@ module System.CPUTime
 
 import Prelude
 
+import Data.Ratio
+
+#ifdef __HUGS__
+import Hugs.Time ( getCPUTime, clockTicks )
+#endif
+
+#ifdef __GLASGOW_HASKELL__
 import Foreign
 import Foreign.C
 
-import Data.Ratio
-
 #include "HsBase.h"
+#endif
 
+#ifdef __GLASGOW_HASKELL__
 -- -----------------------------------------------------------------------------
--- Computation `getCPUTime' returns the number of picoseconds CPU time
+-- |Computation 'getCPUTime' returns the number of picoseconds CPU time
 -- used by the current program.  The precision of this result is
 -- implementation-dependent.
 
--- The `cpuTimePrecision' constant is the smallest measurable difference
--- in CPU time that the implementation can record, and is given as an
--- integral number of picoseconds.
-
 getCPUTime :: IO Integer
 getCPUTime = do
 
@@ -84,6 +87,8 @@ foreign import ccall unsafe times :: Ptr CTms -> IO CClock
 #endif
 
 #else /* win32 */
+     -- NOTE: GetProcessTimes() is only supported on NT-based OSes.
+     -- The counts reported by GetProcessTimes() are in 100-ns (10^-7) units.
     allocaBytes (#const sizeof(FILETIME)) $ \ p_creationTime -> do
     allocaBytes (#const sizeof(FILETIME)) $ \ p_exitTime -> do
     allocaBytes (#const sizeof(FILETIME)) $ \ p_kernelTime -> do
@@ -93,11 +98,15 @@ foreign import ccall unsafe times :: Ptr CTms -> IO CClock
     if toBool ok then do
       ut <- ft2psecs p_userTime
       kt <- ft2psecs p_kernelTime
-      return (fromIntegral (ut + kt))
+      return (ut + kt)
      else return 0
-  where ft2psecs ft = do
+  where 
+	ft2psecs :: Ptr FILETIME -> IO Integer
+        ft2psecs ft = do
           high <- (#peek FILETIME,dwHighDateTime) ft :: IO CLong
           low <- (#peek FILETIME,dwLowDateTime) ft :: IO CLong
+	    -- Convert 100-ns units to picosecs (10^-12) 
+	    -- => multiply by 10^5.
           return (((fromIntegral high) * (2^32) + (fromIntegral low)) * 100000)
 
     -- ToDo: pin down elapsed times to just the OS thread(s) that
@@ -110,10 +119,16 @@ foreign import ccall unsafe "GetCurrentProcess" getCurrentProcess :: IO (Ptr HAN
 foreign import ccall unsafe "GetProcessTimes" getProcessTimes :: Ptr HANDLE -> Ptr FILETIME -> Ptr FILETIME -> Ptr FILETIME -> Ptr FILETIME -> IO CInt
 
 #endif /* not _WIN32 */
+#endif /* __GLASGOW_HASKELL__ */
+
+-- |The 'cpuTimePrecision' constant is the smallest measurable difference
+-- in CPU time that the implementation can record, and is given as an
+-- integral number of picoseconds.
 
 cpuTimePrecision :: Integer
 cpuTimePrecision = round ((1000000000000::Integer) % fromIntegral (clockTicks))
 
+#ifdef __GLASGOW_HASKELL__
 clockTicks :: Int
 clockTicks =
 #if defined(CLK_TCK)
@@ -122,3 +137,4 @@ clockTicks =
     unsafePerformIO (sysconf (#const _SC_CLK_TCK) >>= return . fromIntegral)
 foreign import ccall unsafe sysconf :: CInt -> IO CLong
 #endif
+#endif /* __GLASGOW_HASKELL__ */