C CRC Code(JNI)

JNIEXPORT를 한 이유는 아래 DLL을

JAVA에서 사용하려고........

C에서만 사용하는 거라면 변수 타입에 j붙은거 떼고..

#include <stdio.h>
#include <string.h>
#include "CRC16.h"
//2019 01 28 HJH - CRC16 GENERATOR TEST
JNIEXPORT int JNICALL Java_CRC16_byteArray(JNIEnv *env, jobject jobj,jbyteArray jsrc)
{
        jbyteArray result;
        jsize n = (*env)->GetArrayLength(env,jsrc);
        jbyte *pbyte = (*env)->GetByteArrayElements(env,jsrc,0);
        jbyte value;
        result = (*env)->NewByteArray(env,n);
 
        unsigned char btData[n];
        memset(btData,0,sizeof(btData));
 
        for(int k=0;k<n;k++)
        {
                (*env)->GetByteArrayRegion(env,jsrc,k,1,&value);
                btData[k] = (unsigned char)value;
                //(*env)->SetByteArrayRegion(env,result,k,1,&value);
        }
 
        int nOffset = 0;
        int nWords = 13; /*필요 시 매개변수로 받아서*/
 
        unsigned short  wCRC16 = 0xA5A5;
        unsigned short *pwData = (unsigned short*)(btData + nOffset);
 
        for (int i = 0; i < nWords; i++)
        {
                //wCRC16 = wCRC16 ^ pwData[i];
        wCRC16 = pwData[i] ^ wCRC16;
        }
 
        unsigned char convEndian[2];
        int ret;
 
        convEndian[0] = (unsigned short)((wCRC16 >> 0) & 0xff);
        convEndian[1] = (unsigned short)((wCRC16 >> 8) & 0xff);
 
        ret = ((unsigned short)convEndian[0] << 8) | ((unsigned short)convEndian[1] << 0);
 
        return ret;
}