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Commit e52bc7c2 authored by David Decotigny's avatar David Decotigny Committed by David S. Miller
Browse files

lib/bitmap.c: conversion routines to/from u32 array 



Aimed at transferring bitmaps to/from user-space in a 32/64-bit agnostic
way.

Tested:
  unit tests (next patch) on qemu i386, x86_64, ppc, ppc64 BE and LE,
  ARM.

Signed-off-by: default avatarDavid Decotigny <decot@googlers.com>
Reviewed-by: default avatarBen Hutchings <ben@decadent.org.uk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 76d13b56

include/linux/bitmap.h

+10 −0
Original line number Diff line number Diff line
@@ -59,6 +59,8 @@ 
 * bitmap_find_free_region(bitmap, bits, order)	Find and allocate bit region

 * bitmap_release_region(bitmap, pos, order)	Free specified bit region

 * bitmap_allocate_region(bitmap, pos, order)	Allocate specified bit region

 * bitmap_from_u32array(dst, nbits, buf, nwords) *dst = *buf (nwords 32b words)

 * bitmap_to_u32array(buf, nwords, src, nbits)	*buf = *dst (nwords 32b words)

 */



/*
@@ -163,6 +165,14 @@ extern void bitmap_fold(unsigned long *dst, const unsigned long *orig, 
extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);

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 unsigned int bitmap_from_u32array(unsigned long *bitmap,

					 unsigned int nbits,

					 const u32 *buf,

					 unsigned int nwords);

extern unsigned int bitmap_to_u32array(u32 *buf,

				       unsigned int nwords,

				       const unsigned long *bitmap,

				       unsigned int nbits);

#ifdef __BIG_ENDIAN

extern void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);

#else

lib/bitmap.c

+89 −0
Original line number Diff line number Diff line
@@ -12,6 +12,8 @@ 
#include <linux/bitmap.h>

#include <linux/bitops.h>

#include <linux/bug.h>

#include <linux/kernel.h>

#include <linux/string.h>



#include <asm/page.h>

#include <asm/uaccess.h>
@@ -1059,6 +1061,93 @@ int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order) 
}

EXPORT_SYMBOL(bitmap_allocate_region);



/**

 * bitmap_from_u32array - copy the contents of a u32 array of bits to bitmap

 *	@bitmap: array of unsigned longs, the destination bitmap, non NULL

 *	@nbits: number of bits in @bitmap

 *	@buf: array of u32 (in host byte order), the source bitmap, non NULL

 *	@nwords: number of u32 words in @buf

 *

 * copy min(nbits, 32*nwords) bits from @buf to @bitmap, remaining

 * bits between nword and nbits in @bitmap (if any) are cleared. In

 * last word of @bitmap, the bits beyond nbits (if any) are kept

 * unchanged.

 *

 * Return the number of bits effectively copied.

 */

unsigned int

bitmap_from_u32array(unsigned long *bitmap, unsigned int nbits,

		     const u32 *buf, unsigned int nwords)

{

	unsigned int dst_idx, src_idx;



	for (src_idx = dst_idx = 0; dst_idx < BITS_TO_LONGS(nbits); ++dst_idx) {

		unsigned long part = 0;



		if (src_idx < nwords)

			part = buf[src_idx++];



#if BITS_PER_LONG == 64

		if (src_idx < nwords)

			part |= ((unsigned long) buf[src_idx++]) << 32;

#endif



		if (dst_idx < nbits/BITS_PER_LONG)

			bitmap[dst_idx] = part;

		else {

			unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);



			bitmap[dst_idx] = (bitmap[dst_idx] & ~mask)

				| (part & mask);

		}

	}



	return min_t(unsigned int, nbits, 32*nwords);

}

EXPORT_SYMBOL(bitmap_from_u32array);



/**

 * bitmap_to_u32array - copy the contents of bitmap to a u32 array of bits

 *	@buf: array of u32 (in host byte order), the dest bitmap, non NULL

 *	@nwords: number of u32 words in @buf

 *	@bitmap: array of unsigned longs, the source bitmap, non NULL

 *	@nbits: number of bits in @bitmap

 *

 * copy min(nbits, 32*nwords) bits from @bitmap to @buf. Remaining

 * bits after nbits in @buf (if any) are cleared.

 *

 * Return the number of bits effectively copied.

 */

unsigned int

bitmap_to_u32array(u32 *buf, unsigned int nwords,

		   const unsigned long *bitmap, unsigned int nbits)

{

	unsigned int dst_idx = 0, src_idx = 0;



	while (dst_idx < nwords) {

		unsigned long part = 0;



		if (src_idx < BITS_TO_LONGS(nbits)) {

			part = bitmap[src_idx];

			if (src_idx >= nbits/BITS_PER_LONG)

				part &= BITMAP_LAST_WORD_MASK(nbits);

			src_idx++;

		}



		buf[dst_idx++] = part & 0xffffffffUL;



#if BITS_PER_LONG == 64

		if (dst_idx < nwords) {

			part >>= 32;

			buf[dst_idx++] = part & 0xffffffffUL;

		}

#endif

	}



	return min_t(unsigned int, nbits, 32*nwords);

}

EXPORT_SYMBOL(bitmap_to_u32array);



/**

 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.

 * @dst:   destination buffer