Regarding readb and readw functionality

Can u please help with this api
while (((c=readw(URX1)) & 0x2000) == 0) {

is readw corresponding to read word?
what does URX1 stand for? is it a buffer to receive data
any reason to do & 0x2000

It would be better if u can provide the function defination for readw, readb, writeb, writew

I am getting some undefined reference issue