problem using epcs.c in SDK library

Hello,

I have problem calling "nr_epcs_is_device_present()" function

which I copied & pasted from epcs.c in SDK library.

As far as I can see from the original source,

The first thing it does in there is calling "nr_epcs_set_cs()" function

to set chip select.

After that, it is calling "nr_epcs_txchar(na_epcs_wren)" function

to send WRITE ENABLE command.

However, below loop in "nr_epcs_txchar(na_epcs_wren)" function continues forever.

----------------------

while (!(na_epcs_controller->np_epcsstatus & np_epcsstatus_rrdy_mask));

----------------------

The base address of my epcs_controller is 0x00900000:

typedef volatile struct{

int np_dummy[256]; // EPCS component fills lower 1k with code

int np_epcsrxdata; // Read-only, 1-16 bit

int np_epcstxdata; // Write-only, same width as rxdata

int np_epcsstatus; // Read-only, 9-bit

int np_epcscontrol; // Read/Write, 9-bit

int np_epcsreserved; // reserved

int np_epcsslaveselect; // Read/Write, 1-16 bit, master only

int np_epcsendofpacket; // Read/write, same width as txdata, rxdata.

} np_epcs;

np_epcs* na_epcs_controller = (np_epcs*)(0x00900000);

I am using NIOS II, and I heard that this legacy SDK is for NIOS.

Is this the reason for my problem?

If so, I would like to hear some hints as to modifying the above source.