Words are swapped after DMA transfer

Code for the second DMA transaction (where something goes wrong.)

/******************************************************************
*  Copy 1/3 to 2/3th of DDR2 memory to 2/3 to end of memory    
******************************************************************/
 
void dma_driver_33_66 ()
{
int i;
int rc;    //request
  alt_dma_txchan txchan;
  alt_dma_rxchan rxchan;
 
void* tx_data = (void*)ALTMEMDDR_1_BASE+0x1500004; /* pointer to data to send */
void* rx_buffer = (void*)(ALTMEMDDR_1_BASE+0x3000004); /* pointer to rx buffer */
  txrx_done=0;
/* Create the transmit channel */
if ((txchan = alt_dma_txchan_open("/dev/dma_tester")) == NULL)
  {
      printf ("Failed to open transmit channel\n");
      exit (1);
  }
 
/* Create the receive channel */
if ((rxchan = alt_dma_rxchan_open("/dev/dma_tester")) == NULL)
  {
      printf ("Failed to open receive channel\n");
      exit (1);
  }
 
/* Post the transmit request */
if ((rc = alt_dma_txchan_send (txchan,
          tx_data,
          0x150000,
NULL,
NULL)) < 0)
  {
      printf ("Failed to post transmit request, reason = %i\n", rc);
      exit (1);
  }
 
/* Post the receive request */
if ((rc = alt_dma_rxchan_prepare (rxchan,
          rx_buffer,
          0x150000,
          txrxDone,
NULL)) < 0)
  {
      printf ("Failed to post read request, reason = %i\n", rc);
      exit (1);
  }
 
/* wait for transfer to complete */
while (!txrx_done);
  printf ("Second transfer successful!\n");
 
  printf("Content of DDR2 SDRAM after DMA operation\n");
for (i=0x0;i<0x20;i+=4)
  {
      printf("Address 0x%X: %x\n",i+(int)tx_data,IORD_32DIRECT((int)tx_data,i));
  }
//IOWR_32DIRECT(rx_buffer, 0, 0x11);
  printf("Content of DDR2 SDRAM after DMA operation\n");
for (i=0x0;i<0x20;i+=4)
  {
      printf("Address 0x%X: %x\n",i+((int)rx_buffer),IORD_32DIRECT((int)rx_buffer,i));
  }
 
}