Android RegisterNatives

gistfile1.txt

#include <stdio.h>
#include <android/log.h>
#include "calvals.h"

#define EXPORT __attribute__((visibility("default")))
#define LOG_TAG "native"

#define log_info(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
#define log_error(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)

#define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))


jint addVals(JNIEnv *env, jobject thiz, jint a, jint b)
{
  return a + b;
}
															  
jint subVals(JNIEnv *env, jobject thiz, jint a, jint b)
{
  return a - b;
}
															  
jint mulVals(JNIEnv *env, jobject thiz, jint a, jint b)
{
  return a * b;
}

jint divVals(JNIEnv *env, jobject thiz, jint a, jint b)
{
  return a / b;
}


int jniRegisterNativeMethods(JNIEnv *env, const char *className,
                             const JNINativeMethod *gMethods, int numMethods)
{
  jclass klass;
  
  log_info("Registering %s natives\n", className);
  klass = (*env)->FindClass(env, className);
  if(klass == NULL){
    log_error("Native registration unable to find class %s\n", className);
    return -1;
  }

  if((*env)->RegisterNatives(env, klass, gMethods, numMethods) < 0){
    log_error("RegisterNatives failed ofr %s\n", className);
    return -1;
  }

  return 0;  
}


static JNINativeMethod sMethods[] = {
  {"addVals", "(II)I", (void*)addVals},
  {"subVals", "(II)I", (void*)subVals},
  {"mulVals", "(II)I", (void*)mulVals},
  {"divVals", "(II)I", (void*)divVals}
};


EXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved)
{
  JNIEnv *env = NULL;
  
  if((*vm)->GetEnv(vm, (void**)&env, JNI_VERSION_1_6) != JNI_OK)
    return -1;

  jniRegisterNativeMethods(env, "dev/android/sample/AndroidNDKSampleActivity", sMethods, NELEM(sMethods));
  return JNI_VERSION_1_6;
}