#include "javatech_jni22_ArrayExample.h"

JNIEXPORT jfloat JNICALL
    Java_javatech_jni22_ArrayExample_nativeProcessArray
    (JNIEnv *jenv, jobject, jfloatArray the_jarray, jint j_index)
{
    float* c_array = jenv->GetFloatArrayElements (the_jarray, NULL);
    c_array[3] = -999.f;
    int c_index = j_index;
    float element = c_array[c_index];
    jenv->ReleaseFloatArrayElements (the_jarray, c_array, 0);
    jfloat jelement = element;
    return jelement;
} // nativeProcessArray


JNIEXPORT jint JNICALL
    Java_javatech_jni22_ArrayExample_nativeProcessArrayRegion
    (JNIEnv *jenv, jobject, jintArray the_jarray)
{
    jint region[10];
    jint sum = 0;
    jenv->GetIntArrayRegion (the_jarray, 5, 10, region);
    for (int i=0; i < 10; i++)
	sum += region[i];
    return sum;
} // nativeProcessArrayRegion


JNIEXPORT void JNICALL
    Java_javatech_jni22_ArrayExample_nativeModifyArrayRegion
    (JNIEnv *jenv, jobject, jintArray the_jarray)
{
    jint region[10];
    for (int i=0; i < 10; i++)
	region[i] = -5 - i;
    jenv->SetIntArrayRegion (the_jarray, 5, 10, region);
} // nativeProcessArrayRegion


JNIEXPORT void JNICALL
    Java_javatech_jni22_ArrayExample_nativeProcess2DArray
    (JNIEnv *jenv, jobject, jobjectArray joa2d)
{
    // Get the length of the 2D array
    jint len1 = jenv->GetArrayLength (joa2d);
    // Extract the 0-th element from the 2D array and cast into a jintArray
    jintArray i2d_0 = (jintArray) jenv->GetObjectArrayElement (joa2d, 0);
    // Get the length of the extracted 1D array
    jint len2 = jenv->GetArrayLength (i2d_0);

    // Allocate a buffer to receive a copy of the elements from the 1D array
    jint buffer[4];
    // Copy the all of the elements of the entire 1D array into the buffer
    jenv->GetIntArrayRegion (i2d_0, 0, 4, buffer);
    // Modify them in some way.
    for (int i=0; i < 4; i++)
	buffer[i]*=2;
    // Insert the modified buffer back into the 1D array.
    jenv->SetIntArrayRegion (i2d_0, 0, 4, buffer);
} // nativeProcessArrayRegion