PCI_Features
  Bit 0: Special cycles supported
  Bit 1: Memory read/write supported
  Bit 2: Failed transfers may cause aborts
  Bit 3: Host bridge is fast back-to-back capable

PCI_ReadConfigByte
PCI_ReadConfigHalfword
PCI_ReadConfigWord
PCI_WriteConfigByte
PCI_WriteConfigHalfword
PCI_WriteConfigWord

size_t PCI_Addresses(void *buffer, size_t buffersz)
  word 0: Memory base
  word 1: Memory size
  word 2: Memory offset (physical address minus PCI address)
  word 3: IO base
  word 4: IO size
  word 5: IO offset (physical address minus PCI address)
  word 6: RAM PCI address

void PCI_SpecialCycle(uint32_t message)

size_t PCI_SlotTable(void *buffer, size_t buffersz)

