arrayCopy

Hi folks,

While looking at the usage of the method System.arraycopy
in Java, I found it very useful function.
for example, in java.util.ArrayList it is doing may useful shifting operations.

So, I decide to try to write a similar function, but instead of using the pattern "func (src, dest)" of java, I used instead the pattern "func(dest, src)" of C.

The Header file:

#ifndef ARRAYUTIL_H
#define ARRAYUTIL_H

#include <stddef.h>

/**
 * dest    destination array
 * dIndex    index to which we will start copying
 * src        source array
 * sIndex    index from which we will start copying
 * len        number of elements that will be copied from source array
 * destArrLen    the length of the destination array (hence C doesn't know any length info about passed arrays)
 * size    the size of the type of the array (ex: if the array of type long, put in this parameter sizeof(long))
 */
void arraryCopy(void *dest, int dIndex, const void* src, int sIndex, int len, int destArrLen, size_t size);

#endif // ARRAYUTIL_H

The impl file:

#include <string.h>
#include <stdint.h>
#include <stdlib.h>

#include <arrays/ArrayUtil.h>

void arraryCopy(void *dest, int dIndex, const void* src, int sIndex, int len, int destLen, size_t size)
{
   uint8_t *udest = (uint8_t*) dest;
   uint8_t *usrc = (uint8_t*) src;
   dIndex  *= size;
   sIndex  *= size;
   len     *= size;
   destLen *= size;
  
   if (src != dest)
   {
   memcpy(&udest[dIndex], &usrc[sIndex], len);
   }else
   {
   if (dIndex > sIndex)
   {
       uint8_t *tmp = (uint8_t*) calloc(destLen, size);
       memcpy(tmp, &udest[dIndex], (destLen-dIndex));
       memcpy(&udest[dIndex], &usrc[sIndex], len);
       memcpy(&udest[dIndex+len], tmp, (destLen-dIndex));
       free(tmp);
   }else if (sIndex > dIndex)
   {
       memcpy(&udest[dIndex], &usrc[sIndex], (destLen-sIndex)+1);
   }else
       return;
   }
}

And, testing it:

#include <stdio.h>
#include <arrays/ArrayUtil.h>

int main(void)
{
   int arr[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  
   arraryCopy(arr, 1, arr, 2, 1, 10, sizeof(int));
  
   int i;
   for (i=0; i<9; i++)        // the len became 9 here because we do shift left by 1
   printf("%i ", arr[i]);
  
   return 0;
}