[PATCH 1/7] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area
From: Akinobu Mita <akinobu.mita@gmail.com>
Date: 2009-10-28 08:43:34
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: sparclinux@vger.kernel.org Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <redacted> Cc: linuxppc-dev@ozlabs.org Cc: Thomas Gleixner <redacted> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Lothar Wassmann <redacted> Cc: linux-usb@vger.kernel.org Cc: Roland Dreier <redacted> Cc: Yevgeny Petrilin <redacted> Cc: netdev@vger.kernel.org Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <redacted> Cc: linux-ia64@vger.kernel.org Cc: linux-altix@sgi.com Cc: Joerg Roedel <redacted> --- include/linux/bitmap.h | 11 ++++++ lib/bitmap.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 92 insertions(+), 0 deletions(-)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 756d78b..daf8c48 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h@@ -42,6 +42,9 @@ * bitmap_empty(src, nbits) Are all bits zero in *src? * bitmap_full(src, nbits) Are all bits set in *src? * bitmap_weight(src, nbits) Hamming Weight: number set bits + * bitmap_set(dst, pos, nbits) Set specified bit area + * bitmap_clear(dst, pos, nbits) Clear specified bit area + * bitmap_find_next_zero_area(buf, len, pos, n, mask) Find bit free area * bitmap_shift_right(dst, src, n, nbits) *dst = *src >> n * bitmap_shift_left(dst, src, n, nbits) *dst = *src << n * bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src)
@@ -108,6 +111,14 @@ extern int __bitmap_subset(const unsigned long *bitmap1, const unsigned long *bitmap2, int bits); extern int __bitmap_weight(const unsigned long *bitmap, int bits); +extern void bitmap_set(unsigned long *map, int i, int len); +extern void bitmap_clear(unsigned long *map, int start, int nr); +extern unsigned long bitmap_find_next_zero_area(unsigned long *map, + unsigned long size, + unsigned long start, + unsigned int nr, + unsigned long align_mask); + extern int bitmap_scnprintf(char *buf, unsigned int len, const unsigned long *src, int nbits); extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 7025658..11bf497 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.
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