1 /* 2 * Copyright (c) 2019, Red Hat, Inc 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 #include <jni.h> 25 26 static jlong fib(jint num) { 27 if (num == 0) { 28 return 0; 29 } 30 if (num <= 2) { 31 return 1; 32 } 33 return fib(num - 2) + fib(num -1); 34 } 35 36 static void callCallback(JNIEnv *env, jclass cls, jobject target, jlong result) { 37 jmethodID mid = (*env)->GetMethodID(env, cls, "callback", "(J)V"); 38 if (mid == NULL) { 39 jclass nsme = (jclass) (*env)->NewGlobalRef(env, 40 (*env)->FindClass(env, 41 "java/lang/NoSuchMethodException")); 42 if (nsme != NULL) { 43 (*env)->ThrowNew(env, nsme, "Can't find method callback()"); 44 } 45 return; 46 } 47 (*env)->CallVoidMethod(env, target, mid, result); 48 } 49 50 static void calculateAndCallCallback(JNIEnv *env, jclass cls, jobject target, jint num) { 51 jlong result = -1; 52 result = fib(num); 53 callCallback(env, cls, target, result); 54 } 55 56 JNIEXPORT void JNICALL 57 Java_fib_FibJNI_callJNI(JNIEnv *env, jclass cls, jobject target, jint num) { 58 calculateAndCallCallback(env, cls, target, num); 59 }