Hi Kostirya,
On 24/05/2016 09:07, Kostirya wrote:
Hello.
I have some questions about Foreign.
1. How to convert OS.IO.iodesc (from socket) into cUint (uintptr_t)?
The Basis Library docs explain about converting iodesc values and
portability issues:
http://sml-family.org/Basis/os-io.html#SIG:OS_IO.iodesc:TY
With Poly/ML, if you want to pass an iodesc value to/from a C function
you probably want to create your own conversion by building on cUint.
See (untested) code below that creates cIoDescConv. Note that valOf may
raise an exception.
2. C function is need 'const struct timespec *timeout' argument.
Where struct timespec is:
struct timespec {
time_t tv_sec;
long tv_nsec;
};
Do I understand correctly that this is
cOptionPtr (cStruct2 (cInt32, cLong))
?
But how can I call this from polyml?
I call as SAME (3, 0) and got error: Exception- Foreign "cOptionPtr must
be applied to a pointer type" raised
You need to use cStar or cConstStar for the dereferencing. It looks
like you want
cConstStar (cStruct2 (cInt32, cLong))
Whether you use cOptionPtr around that depends on whether you want to be
able to pass a null/non-null pointer for an optional value.
Phil
fun convMap (fromC, toC) conv =
let
open Foreign
val {ctype, load, store} = breakConversion conv
in
makeConversion {
ctype = ctype,
load = fromC o load,
store = fn (p, x) => store (p, toC x)
}
end
val cFileDescConv =
convMap
(
Posix.FileSys.wordToFD o SysWord.fromInt,
SysWord.toInt o Posix.FileSys.fdToWord
)
Foreign.cUint
val cIoDescConv =
convMap
(Posix.FileSys.fdToIOD, valOf o Posix.FileSys.iodToFD)
cFileDescConv
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