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scoutfs-utils: resurrect bitops

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We've had these in the past and we need them again for the block
allocator item bitmaps.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2019-10-28 14:24:47 -07:00
committed by Zach Brown
parent 3776c18c66
commit c87a9f3a07
1 changed files with 101 additions and 0 deletions
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101
utils/src/bitops.h Normal file
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#ifndef _BITOPS_H_
#define _BITOPS_H_
#include "sparse.h"
/*
* Implement little endian bitmaps in terms of native longs. __packed
* is used to avoid unaligned accesses. These are neither atomic nor
* particularly efficient.
*/
#define BITS_PER_LONG (sizeof(long) * 8)
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define BITOP_LE_SWIZZLE 0
#else
#define BITOP_LE_SWIZZLE ((BITS_PER_LONG-1) & ~0x7)
#endif
static inline unsigned long get_nr_word(int nr, void *addr)
{
unsigned long *longs = addr;
unsigned long ind = nr / BITS_PER_LONG;
unsigned long val;
memcpy(&val, &longs[ind], sizeof(val));
return val;
}
static inline void put_nr_word(int nr, void *addr, unsigned long val)
{
unsigned long *longs = addr;
unsigned long ind = nr / BITS_PER_LONG;
memcpy(&longs[ind], &val, sizeof(val));
}
static inline unsigned long nr_mask(int nr)
{
return 1UL << (nr % BITS_PER_LONG);
}
static inline int test_bit(int nr, void *addr)
{
unsigned long val = get_nr_word(nr, addr);
return !!(val & nr_mask(nr));
}
static inline void set_bit(int nr, void *addr)
{
unsigned long val = get_nr_word(nr, addr);
val |= nr_mask(nr);
put_nr_word(nr, addr, val);
}
static inline void clear_bit(int nr, void *addr)
{
unsigned long val = get_nr_word(nr, addr);
val &= ~nr_mask(nr);
put_nr_word(nr, addr, val);
}
static inline int test_bit_le(int nr, void *addr)
{
return test_bit(nr ^ BITOP_LE_SWIZZLE, addr);
}
static inline int test_and_set_bit_le(int nr, void *addr)
{
int ret;
nr ^= BITOP_LE_SWIZZLE;
ret = test_bit(nr, addr);
set_bit(nr, addr);
return ret;
}
static inline void set_bit_le(int nr, void *addr)
{
set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
}
static inline void clear_bit_le(int nr, void *addr)
{
clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
}
static inline int test_and_clear_bit_le(int nr, void *addr)
{
int ret;
nr ^= BITOP_LE_SWIZZLE;
ret = test_bit(nr, addr);
clear_bit(nr, addr);
return ret;
}
#endif