I am trying to call a precompiled C function that uses a struct as one of
it's arguments.
I could write a wrapper function in C, but I was hoping there is some way
to
pack fields into an array of type raw that could be passed directly to the
function.
Here is some more detail. The C struct is simple, but has mixed types:
struct STRUCT1 {
long type;
long nx;
double *x;
double a;
double b;
};
typedef struct STRUCT1 STRUCT1_TYPE;
The C function header is
void func1( long method, STRUCT1 my_struct, double *output);
I would like to have an R list mimicking the C struct,
and then use .C to call func1 with this information, e.g.
my.struct <- list(type=3,nx=5,x=1:5,a=2.5,b=8.3)
my.func1( 3, convert2raw( my.struct ), )
where R function convert2raw would return a vector of type raw with
the fields of my.struct packed into memory just like STRUCT1, and then
I could call func1 with that vector of raws.
Can I write a convert2raw( ) function and then use
my.func1 <- function( method, buf ) {
a <- .C("func1", as.integer(method), as.raw(buf) , output=double(1)
)
return(a$output)
}
John
...........................................................................
John P. Nolan
Math/Stat Department
227 Gray Hall
American University
4400 Massachusetts Avenue, NW
Washington, DC 20016-8050
[EMAIL PROTECTED]
202.885.3140 voice
202.885.3155 fax
http://academic2.american.edu/~jpnolan
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