If you are using hsc2hs (if you are using Cabal this is easy; just
rename the file to *.hsc and Cabal will take care of the rest), then
there is a macro for making this easier and so you don't have to think
about it.
First, place the following at the top of your source file:
#let alignment t = "%lu", (unsigned long)offsetof(struct {char x__; t
(y__); }, y__)
Then #{alignment c_type} will always be expanded by hsc2hs to the
correct alignment for the C type named c_type.
On Sat, Nov 15, 2008 at 3:29 PM, Maurício
Hi,
I need to make the following structure into an instance of Storable:
struct { double w[2]; }
Can I assume that its function 'alignment' should return the same as "alignment (1::CDouble)"? Or should it be "2 * alignment (1::CDouble)"?
(I've read the wikipedia article about memory alignment, and what I understand is that there's a better alignment for hardware efficiency but compilers and programmers can do almost anything about it. What can I do when writing a library wrapper if I don't know what kind of compiler pragmas were used in all platforms that library was compiled?)
Thanks, Maurício
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