[Etherboot-developers] why does scan_bus() in pci.c ....?

[Eno C. <Eno...@Mi...>]

Dear List

Have been looking at the logic in scan_bus() in pci.c. When it finds an
ethernet controller, it sets up a loop to read through the 6 base address
double words The code in the loop ...

1. reads the indicated base address double word. word 0 first, word 1
second, etc
2. if the base address is zero, the code continues at step 1
3. is the base address refers to memory space (as opposed to i/o space), the
code continues at step 1

Otherwise, the code continues, apparently on the assumption, it has what it
needs. It

4. clears the least significant two bits from the i/o space base address,
and
5. reads base address double word 1 into a cell called membase, and
6. reads the rom base address double word into a cell called romaddr, and
7. continues with some other stuff that isn't germane to this topic, and
8. CONTINUES WITH THE LOOP

This last step confuses me. Am I missing something about how pci works?
Ought not the code break from the loop when it has detected the address data
it needs to access the device?

Eno Compton