#include <stdio.h>
typedef unsigned long __uint64_t;
typedef struct xfs_bmbt_rec_64
{
        __uint64_t              l0, l1;
} xfs_bmbt_rec_64_t;

typedef __uint64_t      xfs_bmbt_rec_base_t;    
typedef xfs_bmbt_rec_64_t xfs_bmbt_rec_t, xfs_bmdr_rec_t;

typedef enum {
       XFS_EXT_NORM, XFS_EXT_UNWRITTEN,
       XFS_EXT_DMAPI_OFFLINE
} xfs_exntst_t;

typedef struct xfs_bmbt_irec
{
	__uint64_t   br_startoff;    /* starting file offset */
	__uint64_t   br_startblock;  /* starting block number */
	__uint64_t   br_blockcount;  /* number of blocks */
	xfs_exntst_t    br_state;       /* extent state */
} xfs_bmbt_irec_t;

#define XFS_MASK64LO(n)         (((__uint64_t)1 << (n)) - 1)
#define XFS_MASK64HI(n)         ((__uint64_t)-1 << (64 - (n)))

int main(void) 
{
	xfs_bmbt_irec_t s;
	xfs_bmbt_rec_t  r;
	int extent_flag;

	s.br_startoff = 0;
	s.br_blockcount = 5;
	s.br_startblock = 0xfffffffffffffff0;
	extent_flag = (s.br_state == XFS_EXT_NORM) ? 0 : 1;

	printf("blockcount = 0x%llx\n", s.br_startblock);
	r.l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
	          ((xfs_bmbt_rec_base_t)s.br_startoff << 9) |
	          ((xfs_bmbt_rec_base_t)s.br_startblock >> 43);
	r.l1 = ((xfs_bmbt_rec_base_t)s.br_startblock << 21) |
	         ((xfs_bmbt_rec_base_t)s.br_blockcount &
	         (xfs_bmbt_rec_base_t)XFS_MASK64LO(21));

	printf("l0 = 0x%llx l1 = 0x%llx\n", r.l0, r.l1);

	r.l0 = (r.l0 & (xfs_bmbt_rec_base_t)XFS_MASK64HI(55)) |
	        (xfs_bmbt_rec_base_t)((__uint64_t)100 >> 43);
	r.l1 = (r.l1 & (xfs_bmbt_rec_base_t)XFS_MASK64LO(21)) |
	        (xfs_bmbt_rec_base_t)((__uint64_t)100 << 21);

	printf("l0 = 0x%llx l1 = 0x%llx\n", r.l0, r.l1);
	return 0;
}