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author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2012-08-13 15:39:10 -0400 |
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committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2012-08-13 15:39:10 -0400 |
commit | 0980bd9cd32de2fef7eaa2858345c49d14498625 (patch) | |
tree | 41f5f823d0569a81b22037e79c22d823933a63f1 /lib/memweight.c | |
parent | 78821b2c0299ab807d483802f09897728b93bce0 (diff) | |
parent | 0d7614f09c1ebdbaa1599a5aba7593f147bf96ee (diff) |
Merge commit 'v3.6-rc1' into linux-next
* commit 'v3.6-rc1': (9532 commits)
Linux 3.6-rc1
mm: remove node_start_pfn checking in new WARN_ON for now
ARM: mmp: add missing irqs.h
arm: mvebu: fix typo in .dtsi comment for Armada XP SoCs
ARM: PRIMA2: delete redundant codes to restore LATCHED when timer resumes
libceph: fix crypto key null deref, memory leak
ceph: simplify+fix atomic_open
sh: explicitly include sh_dma.h in setup-sh7722.c
um: Add arch/x86/um to MAINTAINERS
um: pass siginfo to guest process
um: fix ubd_file_size for read-only files
md/dm-raid: DM_RAID should select MD_RAID10
md/raid1: submit IO from originating thread instead of md thread.
raid5: raid5d handle stripe in batch way
raid5: make_request use batch stripe release
um: pull interrupt_end() into userspace()
um: split syscall_trace(), pass pt_regs to it
um: switch UPT_SET_RETURN_VALUE and regs_return_value to pt_regs
MIPS: Loongson 2: Sort out clock managment.
locks: remove unused lm_release_private
...
Diffstat (limited to 'lib/memweight.c')
-rw-r--r-- | lib/memweight.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/lib/memweight.c b/lib/memweight.c new file mode 100644 index 000000000000..e35fc8771893 --- /dev/null +++ b/lib/memweight.c @@ -0,0 +1,38 @@ +#include <linux/export.h> +#include <linux/bug.h> +#include <linux/bitmap.h> + +/** + * memweight - count the total number of bits set in memory area + * @ptr: pointer to the start of the area + * @bytes: the size of the area + */ +size_t memweight(const void *ptr, size_t bytes) +{ + size_t ret = 0; + size_t longs; + const unsigned char *bitmap = ptr; + + for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long); + bytes--, bitmap++) + ret += hweight8(*bitmap); + + longs = bytes / sizeof(long); + if (longs) { + BUG_ON(longs >= INT_MAX / BITS_PER_LONG); + ret += bitmap_weight((unsigned long *)bitmap, + longs * BITS_PER_LONG); + bytes -= longs * sizeof(long); + bitmap += longs * sizeof(long); + } + /* + * The reason that this last loop is distinct from the preceding + * bitmap_weight() call is to compute 1-bits in the last region smaller + * than sizeof(long) properly on big-endian systems. + */ + for (; bytes > 0; bytes--, bitmap++) + ret += hweight8(*bitmap); + + return ret; +} +EXPORT_SYMBOL(memweight); |