From: Xavier Leroy <Xavier.Leroy@inria.fr>
Message-Id: <199704291542.RAA03587@pauillac.inria.fr>
Subject: Re: Interfacing C procedure using an array as parameter ?
In-Reply-To: <3364B837.4925@parc.anglia.ac.uk> from "Vincent B.G. Leleu" at "Apr 28, 97 03:46:15 pm"
To: vincent@parc.anglia.ac.uk (Vincent B.G. Leleu)
Date: Tue, 29 Apr 1997 17:42:16 +0200 (MET DST)
> This is the first time I interface C/OCaml and also I have
> a problem : How do I use a parameter which is a pointer
> on the beginning of an integer array ?
To get you started, here are functions to convert between a C integer
array and a Caml integer array. (Warning: untested code ahead.)
value c_intarray_to_caml_intarray(int * carray, unsigned int nelts)
{
value mlarray;
int i;
mlarray = nelts < Max_young_wosize ? alloc(nelts, 0) : alloc_shr(nelts, 0);
for (i = 0; i < nelts; i++) Field(mlarray, i) = Val_int(carray[i]);
return mlarray;
}
int caml_intarray_to_c_intarray(value mlarray,
int ** carray /*out parameter*/,
unsigned int * nelts /*out parameter*/)
{
unsigned int len;
int * p;
int i;
len = Wosize_val(mlarray);
p = malloc(len * sizeof(int));
if (p == NULL) return -1;
for (i = 0; i < len; i++) p[i] = Int_val(Field(mlarray, i));
*carray = p;
*nelts = len;
return 0;
}
Hope this helps,
- Xavier Leroy
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