Re: [C2hs] Marshal Haskell list into monolithic arrays

17 Aug 2006


      I freed 'mfs' and 'fsP2' before return also.
...
lowPassFilter :: [CFloat] -> CFloat
lowPassFilter fs =  (unsafePerformIO (lowPassFilterWrap fs))
   where lowPassFilterWrap :: [CFloat] -> IO CFloat
    lowPassFilterWrap fs = do
          mfs <- newArray fs
               fsP2 <- malloc
               r <- f_lowPassFilter mfs fsP2
               returnF <- peek fsP2
               free mfs
               free fsP2
               return returnF
Best wishes,

Yours,
  Jun

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...
From: "zhu Jun" 
To: u.stenzel@web.de
CC: C2hs@haskell.org
Subject: Re: [C2hs] Marshal Haskell list into monolithic arrays
Date: Thu, 17 Aug 2006 21:39:27 +0000
Hi Udo and Duncan,
Yes, I made a mistake in C syntax. Now, I call the function in 
Haskell like this:
-------------------------
lowPassFilter :: [CFloat] -> CFloat
lowPassFilter fs =  (unsafePerformIO (lowPassFilterWrap fs))
   where lowPassFilterWrap :: [CFloat] -> IO CFloat
    lowPassFilterWrap fs = do
          mfs <- newArray fs
               fsP2 <- malloc
               r <- f_lowPassFilter mfs fsP2
               returnF <- peek fsP2
               return returnF
foreign import ccall "static fmr.h lowPassFilter"
 f_lowPassFilter :: Ptr (CFloat) -> Ptr (CFloat) -> IO (())
---------------------------
and the C function is defined as:
////////////////////////
void lowPassFilter(float *buff, float *sum)
{
// Work part
 for (i = 0; i < NUM_TAPS; i++)
 {
   printf("buff %d = %f \n", i, *(buff++));
   *sum += *(buff++) * coeff[i];
 }
}
////////////////////////
It works well! Thank you so much!
Best wishes,
Yours,
 Jun
...
From: Udo Stenzel 
To: zhu Jun 
Subject: Re: [C2hs] Marshal Haskell list into monolithic arrays
Date: Thu, 17 Aug 2006 17:17:21 +0200
...
There is a 'newArray' operation in MarshallArray to marshal 
Haskell
zhu Jun wrote:
list,
...
The C function looks like:
////////////////////
void lowPassFilter(float *fs[10], float *sum)
This function doesn't take (a pointer to) an array of floats, but 
(a
pointer to) an array of pointers to floats, which I doubt was your
intention.  You need help programming in C, not help using C2HS.  
Try a
book or ask in news:comp.lang.c
Udo.
...
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