PCie BAR to memory mapped slave

hi guys!!

Well, I've got trouble with sending a some data to memory mapped slave.

My PCIe just has one BAR.

That Bar has a size of 4kbytes - 12 bits and my memory mapped slave has a 10 bits of address width and 32 data width

(memory mapped slave has address are 0x0000_0000 to 0x0000_0fff).

So my questions are:

1.- if I want to send data to memory slave, How should I fill BAR?:confused:....... Bar has size of 4KBytes and I dont know which bits are of datas and address.

2.- Why dooes BAR has 12 bits if my memory mapped slave has 10 bits??:confused:

Well, Iill be thanking for your replys!!