Messages in this thread Patch in this message | | | From | Rasmus Villemoes <> | Subject | [PATCH 7/8] lib: bitmap: Simplify bitmap_ord_to_pos | Date | Fri, 12 Dec 2014 01:01:53 +0100 |
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Make the return value and the ord and nbits parameters of bitmap_ord_to_pos unsigned.
Also, simplify the implementation and as a side effect make the result fully defined, returning nbits for ord >= weight, in analogy with what find_{first,next}_bit does. This is a better sentinel than the former ("unofficial") 0. No current users are affected by this change.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- include/linux/bitmap.h | 2 +- lib/bitmap.c | 28 +++++++++++----------------- 2 files changed, 12 insertions(+), 18 deletions(-)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 85e8fb091ed7..e854934cdbf9 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -144,7 +144,7 @@ extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order); extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order); extern void bitmap_copy_le(void *dst, const unsigned long *src, int nbits); -extern int bitmap_ord_to_pos(const unsigned long *bitmap, int n, int bits); +extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits); #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG)) #define BITMAP_LAST_WORD_MASK(nbits) \ diff --git a/lib/bitmap.c b/lib/bitmap.c index ab62a7e4d50f..89b61e42f173 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -740,34 +740,28 @@ static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigne * bitmap_ord_to_pos - find position of n-th set bit in bitmap * @buf: pointer to bitmap * @ord: ordinal bit position (n-th set bit, n >= 0) - * @bits: number of valid bit positions in @buf + * @nbits: number of valid bit positions in @buf * * Map the ordinal offset of bit @ord in @buf to its position in @buf. - * Value of @ord should be in range 0 <= @ord < weight(buf), else - * results are undefined. + * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord + * >= weight(buf), returns @nbits. * * If for example, just bits 4 through 7 are set in @buf, then @ord * values 0 through 3 will get mapped to 4 through 7, respectively, - * and all other @ord values return undefined values. When @ord value 3 + * and all other @ord values returns @nbits. When @ord value 3 * gets mapped to (returns) @pos value 7 in this example, that means * that the 3rd set bit (starting with 0th) is at position 7 in @buf. * - * The bit positions 0 through @bits are valid positions in @buf. + * The bit positions 0 through @nbits-1 are valid positions in @buf. */ -int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits) +unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits) { - int pos = 0; + unsigned int pos; - if (ord >= 0 && ord < bits) { - int i; - - for (i = find_first_bit(buf, bits); - i < bits && ord > 0; - i = find_next_bit(buf, bits, i + 1)) - ord--; - if (i < bits && ord == 0) - pos = i; - } + for (pos = find_first_bit(buf, nbits); + pos < nbits && ord; + pos = find_next_bit(buf, nbits, pos + 1)) + ord--; return pos; } -- 2.1.3
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