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Olaf Hering
5028e9bb65
All bitmaps maintained by xc_bitops.h are used in single threaded applications. So nothing will change the bitmaps content, adding volatile adds just unneeded memory reloads. xenpaging uses bitmaps alot and using non-volatile versions will slightly improve performance. Signed-off-by: Olaf Hering <olaf@aepfle.de> Committed-by: Keir Fraser <keir@xen.org>
64 lines
1.5 KiB
C
64 lines
1.5 KiB
C
#ifndef XC_BITOPS_H
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#define XC_BITOPS_H 1
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/* bitmap operations for single threaded access */
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#include <stdlib.h>
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#include <string.h>
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#define BITS_PER_LONG (sizeof(unsigned long) * 8)
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#define ORDER_LONG (sizeof(unsigned long) == 4 ? 5 : 6)
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#define BITMAP_ENTRY(_nr,_bmap) ((_bmap))[(_nr)/BITS_PER_LONG]
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#define BITMAP_SHIFT(_nr) ((_nr) % BITS_PER_LONG)
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/* calculate required space for number of longs needed to hold nr_bits */
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static inline int bitmap_size(int nr_bits)
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{
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int nr_long, nr_bytes;
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nr_long = (nr_bits + BITS_PER_LONG - 1) >> ORDER_LONG;
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nr_bytes = nr_long * sizeof(unsigned long);
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return nr_bytes;
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}
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static inline unsigned long *bitmap_alloc(int nr_bits)
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{
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return calloc(1, bitmap_size(nr_bits));
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}
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static inline void bitmap_clear(unsigned long *addr, int nr_bits)
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{
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memset(addr, 0, bitmap_size(nr_bits));
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}
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static inline int test_bit(int nr, unsigned long *addr)
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{
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return (BITMAP_ENTRY(nr, addr) >> BITMAP_SHIFT(nr)) & 1;
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}
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static inline void clear_bit(int nr, unsigned long *addr)
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{
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BITMAP_ENTRY(nr, addr) &= ~(1UL << BITMAP_SHIFT(nr));
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}
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static inline void set_bit(int nr, unsigned long *addr)
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{
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BITMAP_ENTRY(nr, addr) |= (1UL << BITMAP_SHIFT(nr));
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}
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static inline int test_and_clear_bit(int nr, unsigned long *addr)
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{
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int oldbit = test_bit(nr, addr);
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clear_bit(nr, addr);
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return oldbit;
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}
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static inline int test_and_set_bit(int nr, unsigned long *addr)
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{
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int oldbit = test_bit(nr, addr);
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set_bit(nr, addr);
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return oldbit;
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}
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#endif /* XC_BITOPS_H */
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