Hi,
I've been working on an interface to BLAS recently, and I encountered
a problem with a call to a C function having a `float' argument. The C
function (declaration) is the following:
void cblas_saxpy(const int N, const float alpha, const float *X, const
int incX, float *Y, const int incY);
When I use `foreign import' in ghc-4.08 in the most obvious way (at
least with respect to the `alpha' arg), that is
foreign import "cblas_saxpy" unsafe
cblas_saxpy :: CInt -> CFloat -> ByteArray# -> CInt ->
MutableByteArray# s -> CInt -> IO ()
my code does not produce correct results. However, when I wrap the
`cblas_saxpy' function with a function uses a double arg for `alpha',
and then demotes the value to a float before calling `cblas_saxpy', my
code produces correct results. It appears to me that the FFI is
producing a call to a K&R-style C function that promotes float
arguments to double. If this is what is really happening, is there
some way to change the default style of C-function call to ANSI? On
the other hand, return values of either precision appear to work as I
expect (I don't recall whether K&R also promote float return values to
double).
Cheers,
--
Martin Pokorny
[EMAIL PROTECTED]
