Commit f6a1f5db authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Linus Torvalds
Browse files

lib/bitmap.c: simplify bitmap_ord_to_pos 



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: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent df1d80a9

include/linux/bitmap.h

+1 −1
Original line number Diff line number Diff line
@@ -171,7 +171,7 @@ 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);

extern int bitmap_print_to_pagebuf(bool list, char *buf,

				   const unsigned long *maskp, int nmaskbits);

lib/bitmap.c

+11 −17
Original line number Diff line number Diff line
@@ -771,34 +771,28 @@ 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))

	for (pos = find_first_bit(buf, nbits);

	     pos < nbits && ord;

	     pos = find_next_bit(buf, nbits, pos + 1))

		ord--;

		if (i < bits && ord == 0)

			pos = i;

	}



	return pos;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE