DMA problem

Hi, this is my code:

--- Quote Start ---

# include <stdio.h># include <stdlib.h># include <unistd.h># include "altera_avalon_pio_regs.h"# include "system.h"# include "alt_types.h"# include "sys/alt_dma.h"# include "sys/alt_flash.h" # include "sys/alt_flash_dev.h"# include "altera_avalon_dma_regs.h"# include "altera_avalon_dma.h"

# define loop 16384# define size 65536

static volatile int rx_done = 0;

static void done (void* handle, void* data)

{

rx_done = 1;

}

int main (int argc, char* argv[], char* envp[])

{

alt_flash_fd* fd;

int ret_code, i;

int *src_ptr;

int *dest_ptr;

int addr;

int rc;

alt_dcache_flush_all();

alt_u32 start,end;

alt_dma_txchan txchan;

alt_dma_rxchan rxchan;

addr = 0;

src_ptr = SDRAM_BASE + 0x200000; //Location of data written in SDRAM

dest_ptr = EXT_FLASH_BASE; //Location of data written in flash

void* tx_data = (void*) SDRAM_BASE + 0x200000; /* pointer to data to send */

void* rx_buffer = (void*) EXT_FLASH_BASE + 0x100000; /* pointer to rx buffer */

//Open flash

fd = alt_flash_open_dev(EXT_FLASH_NAME);

if(fd!=NULL)

{

//Generate data into SDRAM

for(i=0;i<loop;i++)

{

IOWR(src_ptr, i, i);

}

//Write data into flash

while(addr < size)

{

ret_code = alt_write_flash(fd, addr, src_ptr+addr, 0x10000);

if(ret_code != 0)

{

printf("Error writing into flash: %d\n", ret_code);

exit(1);

}

addr += 0x10000; // next 64kb block

}

//Read from flash

for(i=0;i<loop;i++)

{

printf("Value at %X is %d, written is %d\n", dest_ptr, *dest_ptr, IORD(src_ptr, i));

dest_ptr++;

}

}else

{

printf("Unable to open flash\n");

exit(1);

}

/* Create the transmit channel */

if ((txchan = alt_dma_txchan_open(DMA_NAME)) == NULL)

{

printf ("Failed to open transmit channel\n");

exit (1);

}

/* Create the receive channel */

if ((rxchan = alt_dma_rxchan_open(DMA_NAME)) == NULL)

{

printf ("Failed to open receive channel\n");

exit (1);

}

/* Post the transmit request */

if ((rc = alt_dma_txchan_send (txchan,

tx_data,

size,

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,

size,

done,

NULL)) < 0)

{

printf ("Failed to post read request, reason = %i\n", rc);

exit (1);

}

/* wait for transfer to complete */

while (!rx_done);

printf ("Transfer successful!\n");

alt_flash_close_dev(fd);

return 0;

}

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I am not sure where it stuck because it does not return any error messages. so i assume dma is working. pls help. thanks!