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authorAkinobu Mita <akinobu.mita@gmail.com>2009-12-15 16:48:25 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-16 07:20:18 -0800
commitc1a2a962a2ad103846e7950b4591471fabecece7 (patch)
tree9a06ab8d1c65037456bad02c821033197f67f03f /lib
parent868d64812ae84e8f094e0bcf95157c7d79d625ec (diff)
downloadlinux-2.6.34-ux500-c1a2a962a2ad103846e7950b4591471fabecece7.tar.gz
bitmap: introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area
This introduces new bitmap functions: bitmap_set: Set specified bit area bitmap_clear: Clear specified bit area bitmap_find_next_zero_area: Find free bit area These are mostly stolen from iommu helper. The differences are: - Use find_next_bit instead of doing test_bit for each bit - Rewrite bitmap_set and bitmap_clear Instead of setting or clearing for each bit. - Check the last bit of the limit iommu-helper doesn't want to find such area - The return value if there is no zero area find_next_zero_area in iommu helper: returns -1 bitmap_find_next_zero_area: return >= bitmap size Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: "David S. Miller" <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Lothar Wassmann <LW@KARO-electronics.de> Cc: Roland Dreier <rolandd@cisco.com> Cc: Yevgeny Petrilin <yevgenyp@mellanox.co.il> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/bitmap.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 702565821c9..11bf4975058 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -271,6 +271,87 @@ int __bitmap_weight(const unsigned long *bitmap, int bits)
}
EXPORT_SYMBOL(__bitmap_weight);
+#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
+
+void bitmap_set(unsigned long *map, int start, int nr)
+{
+ unsigned long *p = map + BIT_WORD(start);
+ const int size = start + nr;
+ int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
+ unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
+
+ while (nr - bits_to_set >= 0) {
+ *p |= mask_to_set;
+ nr -= bits_to_set;
+ bits_to_set = BITS_PER_LONG;
+ mask_to_set = ~0UL;
+ p++;
+ }
+ if (nr) {
+ mask_to_set &= BITMAP_LAST_WORD_MASK(size);
+ *p |= mask_to_set;
+ }
+}
+EXPORT_SYMBOL(bitmap_set);
+
+void bitmap_clear(unsigned long *map, int start, int nr)
+{
+ unsigned long *p = map + BIT_WORD(start);
+ const int size = start + nr;
+ int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+ unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+ while (nr - bits_to_clear >= 0) {
+ *p &= ~mask_to_clear;
+ nr -= bits_to_clear;
+ bits_to_clear = BITS_PER_LONG;
+ mask_to_clear = ~0UL;
+ p++;
+ }
+ if (nr) {
+ mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+ *p &= ~mask_to_clear;
+ }
+}
+EXPORT_SYMBOL(bitmap_clear);
+
+/*
+ * bitmap_find_next_zero_area - find a contiguous aligned zero area
+ * @map: The address to base the search on
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ * @nr: The number of zeroed bits we're looking for
+ * @align_mask: Alignment mask for zero area
+ *
+ * The @align_mask should be one less than a power of 2; the effect is that
+ * the bit offset of all zero areas this function finds is multiples of that
+ * power of 2. A @align_mask of 0 means no alignment is required.
+ */
+unsigned long bitmap_find_next_zero_area(unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr,
+ unsigned long align_mask)
+{
+ unsigned long index, end, i;
+again:
+ index = find_next_zero_bit(map, size, start);
+
+ /* Align allocation */
+ index = __ALIGN_MASK(index, align_mask);
+
+ end = index + nr;
+ if (end > size)
+ return end;
+ i = find_next_bit(map, end, index);
+ if (i < end) {
+ start = i + 1;
+ goto again;
+ }
+ return index;
+}
+EXPORT_SYMBOL(bitmap_find_next_zero_area);
+
/*
* Bitmap printing & parsing functions: first version by Bill Irwin,
* second version by Paul Jackson, third by Joe Korty.