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authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-08-06 09:48:31 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-08-06 09:48:31 -0700
commitc87985a3ce723995fc7b25e598238d67154108a1 (patch)
treee60def1b77c25c1d74180f62e8a5603f9826f209 /lib/memweight.c
parentd155255a344c417acad74156654295a2964e6b81 (diff)
parent0d7614f09c1ebdbaa1599a5aba7593f147bf96ee (diff)
Merge tty-next into 3.6-rc1
This handles the merge issue in: arch/um/drivers/line.c arch/um/drivers/line.h And resolves the duplicate patches that were in both trees do to the tty-next branch not getting merged into 3.6-rc1. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib/memweight.c')
-rw-r--r--lib/memweight.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/lib/memweight.c b/lib/memweight.c
new file mode 100644
index 00000000000..e35fc877189
--- /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);