HELP HELP! writing into flash

I am using DE2 Board. I want to write 1MB of data into flash and my flash is 4MB. My code is below:

--- 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_flash.h" # include "sys/alt_flash_dev.h"

# define size 0xFFFFF

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

{

alt_flash_fd* fd;

int ret_code, i;

int *p1;

int *p2;

p1 = SDRAM_BASE+0x200000;

p2 = EXT_FLASH_BASE;

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

{

IOWR(p1, i, i);

}

fd = alt_flash_open_dev(EXT_FLASH_NAME);

if (fd!=NULL)

{

if((ret_code = alt_write_flash(fd, 0x0, p1, 4096)) == 0)

{

printf("Done writing into flash\n");

printf("Reading data from flash...\n");

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

{

printf("Value at %X is %u\n", p2, *p2);

p2 = p2+1;

}

}else

{

printf("Error in writing to flash\n");

}

}else

{

printf("Error in opening flash\n");

exit(1);

}

printf("DONE\n");

return 0;

}

--- Quote End ---

First, I am storing 1MB of data into SDRAM. then from SDRAM, i write into flash. to test whether the result is correct, I read the data out from the flash. a part of my output is as below:

--- Quote Start ---

Value at 142FFF4 is 49149

Value at 142FFF8 is 49150

Value at 142FFFC is 49151

Value at 1430000 is 4294967295

Value at 1430004 is 4294967295

Value at 1430008 is 4294967295

--- Quote End ---

suppose i will get the 1MB data but it stops at address 142FFFC.

Please help! Thanks!