The code has been imported from the header include/linux/bitops.h in Linux v4.6-rc3.
Signed-off-by: Julien Grall <julien.gr...@arm.com> --- Cc: Ian Jackson <ian.jack...@eu.citrix.com> Cc: Jan Beulich <jbeul...@suse.com> Cc: Keir Fraser <k...@xen.org> Cc: Tim Deegan <t...@xen.org> --- xen/include/xen/bitops.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h index cb56f24..e1a4d93 100644 --- a/xen/include/xen/bitops.h +++ b/xen/include/xen/bitops.h @@ -3,6 +3,17 @@ #include <asm/types.h> /* + * Create a contiguous bitmask starting at bit position @l and ending at + * position @h. For example + * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000. + */ +#define GENMASK(h, l) \ + (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h)))) + +#define GENMASK_ULL(h, l) \ + (((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h)))) + +/* * ffs: find first bit set. This is defined the same way as * the libc and compiler builtin ffs routines, therefore * differs in spirit from the above ffz (man ffs). -- 1.9.1 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
