[5964] in java-interest
Re: How to call java methods and constructors from native C methods ?
daemon@ATHENA.MIT.EDU (Fabrice PARDO)
Wed Mar 6 15:44:27 1996
Date: Wed, 6 Mar 1996 20:02:31 +0100
From: Fabrice PARDO <fabrice.pardo@bagneux.cnet.fr>
To: java-interest@java.sun.com
Cc: fabrice.pardo@bagneux.cnet.fr
I have just got JDK 1.0 source. Thanks Sun. I can respond now my questions
Q1 and Q2
>
> Q1) How can I call methods involving double args
> Now I'm able to call with success execute_java_dynamic_method and
> execute_java_constructor fonctions declared in java1.0/include/interpreter.h
> if args are not double nor java long.
>
> double Test_sqroot(struct HEssai *essai, double d) {
> ClassClass *cc=FindClass(0, "java/lang/Math", 1);
> long ret=execute_java_static_method(0, cc, "sqrt", "(D)D", ?which args?);
> return ?what to return?;
> }
>
>
> Q2) How to pass arguments from a list ? With "..." args in C, I can suppose
> that there is less than (for example) 10 args and pass always 10 args :
> v[0], v[1], v[2], etc. v[9])
> I think there is other functions, able to manipulate java stack.
> Any documentation ?
execute_java_static_method is here an inadequate wrapper to
do_execute_java_method_vararg. Calling do_execute_java_method_vararg
directly works with array datas and returns double half part of 64 bits data.
Other half part need to be referenced by highBits.
do_execute_java_method_vararg is declared in include/interpreter.h
of java-DTK-1.0
long do_execute_java_method_vararg(ExecEnv *ee, void *obj,
char *method_name, char *signature,
struct methodblock *mb,
bool_t isStaticCall, va_list args,
long *highBits, bool_t shortFloats);
As an example, the implementation of a native static method
TryIt.atan2Test(double, double) that is in fact Math.atan2(double, double) :
file TryIt.java:
class TryIt {
public static native double atan2Test(double a, double b);
}
file mathtest.c:
#include <StubPreamble.h>
#include <math.h>
#include "TryIt.h"
double TryIt_atan2Test(struct HTryIt *essai, double a, double b) {
ClassClass *cc;
double args[2];
Java8 sixtyfour;
args[0]=a;
args[1]=b;
cc=FindClass(0, "java/lang/Math", 1);
sixtyfour.x[1]=do_execute_java_method_vararg(
0, cc, "atan2", "(DD)D", 0, TRUE, args, &(sixtyfour.x[0]), FALSE);
return sixtyfour.d;
}
*************************************************************
Fabrice Pardo
Laboratoire de Microstructures et de Micro-Electronique, CNRS
196 avenue Henri Ravera F-92225 Bagneux
(33-1)42.31.75.63
fabrice.pardo@bagneux.cnet.fr
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