struct address_structure
{
    uint8_t address_space_id;    // 0 - system memory, 1 - system I/O
    uint8_t register_bit_width;
    uint8_t register_bit_offset;
    uint8_t reserved;
    uint64_t address;
} __attribute__((packed));

struct description_table_header
{
    char signature[4];    // 'HPET' in case of HPET table
    uint32_t length;
    uint8_t revision;
    uint8_t checksum;
    char oemid[6];
    uint64_t oem_tableid;
    uint32_t oem_revision;
    uint32_t creator_id;
    uint32_t creator_revision;
} __attribute__((packed));

struct hpet : public description_table_header
{
    uint8_t hardware_rev_id;
    uint8_t comparator_count:5;
    uint8_t counter_size:1;
    uint8_t reserved:1;
    uint8_t legacy_replacement:1;
    uint16_t pci_vendor_id;
    address_structure address;
    uint8_t hpet_number;
    uint16_t minimum_tick;
    uint8_t page_protection;
} __attribute__((packed));