C++ към Delphi - добавяне на структура и указател

Имам този макрос, дефиниран в C++;

    #define EXT_FIRST_EXTENT(__hdr__) \
((struct ext4_extent *) (((char *) (__hdr__)) +         \
                         sizeof(struct ext4_extent_header)))

Където ext4_extent_header е структура;

    typedef struct ext4_extent_header {
    uint16_t  eh_magic;       /* probably will support different formats */
    uint16_t  eh_entries;     /* number of valid entries */
    uint16_t  eh_max;         /* capacity of store in entries */
    uint16_t  eh_depth;       /* has tree real underlying blocks? */
    uint32_t  eh_generation;  /* generation of the tree */
}__attribute__ ((__packed__)) EXT4_EXTENT_HEADER;

И ext4_extent също е структура;

typedef struct ext4_extent {
    uint32_t ee_block; /* first logical block extent covers */
    uint16_t ee_len; /* number of blocks covered by extent */
    uint16_t ee_start_hi; /* high 16 bits of physical block */
    uint32_t ee_start_lo; /* low 32 bits of physical block */
} __attribute__ ((__packed__)) EXT4_EXTENT;

Това е моят опит да го напиша в Delphi;

function Ext2Partition.EXT_First_Extent(hdr: PExt4_extent_header):PExt4_ExtEnt;
begin
  Result := PExt4_ExtEnt(hdr + sizeof(ext4_extent_header));
end;

Компилаторът обаче ми казва, че операторът не е приложим за този тип операнд.

Ето моята преобразувана c++ структура в записи на Delphi за ext4_extent_header и ext4_extent;

Type
  PExt4_extent_header = ^Ext4_extent_header;
  Ext4_extent_header = REcord
    eh_magic : Word;
    eh_entries : Word;
    eh_max : Word;
    eh_depth : Word;
    eh_generation : Cardinal;
  End;

Type
  PExt4_ExtEnt = ^Ext4_ExtEnt;
  Ext4_ExtEnt = Record
    ee_block : Cardinal;
    ee_len : Word;
    ee_start_hi : Word;
    ee_start_low : Cardinal;
  End;

Благодаря!