SRF written in C

Hi

what can i do for a SRF written in C, can called as follow:

select * from obtAscendencia('(11099,15685)','(6808,9621)');

I can call the function:
select obtAscendencia('(11099,15685)','(6808,9621)');

the code of function is:

PG_FUNCTION_INFO_V1(obtAscendencia);

Datum
obtAscendencia(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;

intervaloFarey *intF; //intervalo de Farey que
subexiste durente
//la gneracion de lo jerarquia
Racional *r = NULL;//el resultado de obtPadre
Racional *pi; //padre inicial

/* stuff done only on the first call of the function */
if (SRF_IS_FIRSTCALL())
{
MemoryContext oldcontext;

/* create a function context for cross-call persistence
*/
funcctx = SRF_FIRSTCALL_INIT();

intF = (intervaloFarey *)
palloc(sizeof(intervaloFarey));

pi = (Racional *) PG_GETARG_POINTER(0);
intF->izq.num = pi->num;
intF->izq.den = pi->den;

pi = (Racional *) PG_GETARG_POINTER(1);
intF->der.num = pi->num;
intF->der.den = pi->den;


//memeoria fija durante la generacion de la descendencia
directa
funcctx->user_fctx = intF;

oldcontext =
MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

MemoryContextSwitchTo(oldcontext);
}

/* stuff done on every call of the function */
funcctx = SRF_PERCALL_SETUP();

intF = funcctx->user_fctx;//fjmb

// attinmeta = funcctx->attinmeta;

r = obtPadre( &intF->izq, &intF->der );

elog(INFO, "obtAscendencia. retorno de obtPadre. izq : %d,%d
",r->num, r->den);
if ( ( r->num != 1 ) &&
( r->den != 2 ) )
{
char **strRel;
HeapTuple tuple;

//actualizamos la memoria fija durante
//el retorno de los nodos generado
//(ver documentacion de funciones SRF)
intF->der.num = intF->izq.num;
intF->der.den = intF->izq.den;
intF->izq.num = r->num;
intF->izq.den = r->den;

elog(INFO, "obtAscendencia. estructura quedo: %d,%d der:
%d,%d ",
intF->izq.num,
intF->izq.den,
intF->der.num,
intF->der.den
);


SRF_RETURN_NEXT(funcctx, (Datum)(r));
}
else /* do when there is no more left */
{
pfree(intF);
SRF_RETURN_DONE(funcctx);
}
}

definition:

CREATE OR REPLACE FUNCTION obtAscendencia(Racional, Racional)
RETURNS SETOF Racional
AS '/usr/lib/postgresql/farey', 'obtAscendencia'
LANGUAGE C VOLATILE STRICT;

In short, get the direct ancestors of a given node in a tree. This tree
is formed with nested interval and sequence farey. rest of code:

Datum obt_derecho(PG_FUNCTION_ARGS)
{
Racional *p_izq = (Racional *) PG_GETARG_POINTER(0);
Racional *n_izq = (Racional *) PG_GETARG_POINTER(1);
Racional *result = NULL;

result = (Racional *) palloc(sizeof(Racional));
result->num = n_izq->num - p_izq->num;
result->den = n_izq->den - p_izq->den;

PG_RETURN_POINTER(result);
}


Racional* obtPadre( Racional *li, Racional *ld){
Racional *lip;
Racional *tr = NULL; //ap temporal, para hacer el intercambio
bool cont;
int opAnt; //operacion anterior


lip = (Racional *) palloc(sizeof(Racional));
tr = (Racional *) palloc(sizeof(Racional));

cont = true;
opAnt = 0;
while( cont ){

if ( li->num > ld->num ){
//intercambiamos li <-> ld
SWAP_RACIONAL(li, ld );
cont = false;
}
lip->num = ld->num - li->num;
lip->den = ld->den - li->den;
if ( cont ){
while( cont ){
//recorremos
SWAP_RACIONAL(li, ld );
li->num = lip->num;
li->den = lip->den;

if ( li->num > ld->num ){ //si hay intercambio ...
continua en el ciclo
SWAP_RACIONAL(li, ld );
}else{ //si no hay intercambio
cont = false; //salimos del ciclo ....
}
//... pero antes de salir calculamos
lip->num = ld->num - li->num;
lip->den = ld->den - li->den;
}

}
}

return ( lip );
}

Definiton of "Racional" was gotten the manuals of postgres...

thanks in advance