Format of PCI IRQ Routing Table v1.0

Offset  Size    Description     (Table M085)
 00h  4 BYTEs  signature "$PIR"
 04h   WORD    version (0100h for v1.0)
 06h   WORD    table size in bytes
 08h   BYTE    bus number for PCI Interrupt Router
 09h   BYTE    device/function number for PCI Interrupt Router
 0Ah   WORD    bitmap of PCI-exclusive IRQs (bit 0 = IRQ0, etc.)
 0Ch   WORD    PCI vendor ID for compatible PCI Interrupt Router
 0Eh   WORD    PCI device ID for compatible PCI Interrupt Router
 10h   DWORD   Miniport data
 14h 11 BYTEs  reserved (0)
 1Fh   BYTE    checksum (set to make 8-bit sum of bytes in entire structure
         equal 00h)
--- optional data ---
 20h 16 BYTEs  first slot entry (see #M086)
   ...
     16 BYTEs  Nth slot entry