Linuxカーネルにおけるビットマップの使用
3202 ワード
ビットマップタグの使用
#include
#ifdef CONFIG_64BIT
#define BITS_PER_LONG 64
#else
#define BITS_PER_LONG 32
#endif /* CONFIG_64BIT */
/*
unsigned long
*/
#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
/*
@nr unsigned long
*/
#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
#define BITS_PER_BYTE 8
#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
/*
@nr unsigned long
*/
#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
/*
@name[]
unsigned long @bits
*/
#define DECLARE_BITMAP(name,bits) \
unsigned long name[BITS_TO_LONGS(bits)]
/*
include/asm-generic/bitops/non-atomic.h
*/
static inline void __set_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
*p |= mask;
}
static inline void __clear_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
*p &= ~mask;
}
static inline void __change_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
*p ^= mask;
}
/*
test_and_XX_bit @nr
1 -
0 -
*/
static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
unsigned long old;
old = *p;
*p = old | mask;
return (old & mask) != 0;
}
static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
unsigned long old;
old = *p;
*p = old & ~mask;
return (old & mask) != 0;
}
static inline int __test_and_change_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
unsigned long old;
old = *p;
*p = old ^ mask;
return (old & mask) != 0;
}
#define BITS_NR 50
DECLARE_BITMAP(testbit, BITS_NR);
#define ARRAY_SIZE(__arr) (sizeof(__arr) / sizeof(__arr[0]))
void
testbit_dump(void)
{
int size = ARRAY_SIZE(testbit);
printf("array size: %d
", size);
int i;
for (i = 0; i < size; i++)
{
printf("[%d]: 0x%08lx
", i, testbit[i]);
}
printf("
");
}
int
main(void)
{
int b;
testbit_dump();
printf("__set_bit 0
");
__set_bit(0, testbit);
testbit_dump();
printf("__test_and_clear_bit 0
");
b = __test_and_clear_bit(0, testbit);
printf("b: %d
", b);
testbit_dump();
printf("__set_bit 19
");
__set_bit(19, testbit);
testbit_dump();
printf("__clear_bit 0
");
__clear_bit(0, testbit);
testbit_dump();
printf("__test_and_change_bit 33
");
b = __test_and_change_bit(33, testbit);
printf("b: %d
", b);
testbit_dump();
printf("__test_and_clear_bit 33
");
b = __test_and_clear_bit(33, testbit);
printf("b: %d
", b);
testbit_dump();
return 0;
}