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149 lines
3.4 KiB
C
149 lines
3.4 KiB
C
/* $Id: bitfield.h,v 1.1 2005/07/11 10:59:05 jonas Exp $ */
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#ifndef EL__UTIL_BITFIELD_H
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#define EL__UTIL_BITFIELD_H
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#include <string.h>
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#include "util/memory.h"
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/* Bitfield operations: */
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struct bitfield {
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unsigned int bitsize; /* Number of bits in the bitfield. */
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unsigned char bits[1]; /* Strawberry bitfields forever. */
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};
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#define foreach_bitfield_set(bit, bitfield) \
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for ((bit) = 0; (bit) < (bitfield)->bitsize; (bit)++) \
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if (test_bitfield_bit(bitfield, bit))
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#define foreachback_bitfield_set(bit, bitfield) \
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for ((bit) = (bitfield)->bitsize; (bit) > 0;) \
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if (test_bitfield_bit(bitfield, --bit))
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#define foreach_bitfield_cleared(bit, bitfield) \
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for ((bit) = 0; (bit) < (bitfield)->bitsize; (bit)++) \
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if (!test_bitfield_bit(bitfield, bit))
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/* By shifting when getting the bit offset it is ensured that only one bit is
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* set in the resulting value. Idea from libbt by Kevin Smathers. */
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#define get_bitfield_bit_offset(bit) ((size_t) (0x80 >> ((bit) % 8)))
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#define get_bitfield_byte_offset(bit) ((size_t) ((bit) / 8))
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/* +7 to round up to nearest byte. */
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#define get_bitfield_byte_size(bits) ((size_t) (((bits) + 7) / 8))
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/* Allocate a bitfield containing @bits number of bits. */
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static inline struct bitfield *
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init_bitfield(size_t bits)
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{
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size_t size = get_bitfield_byte_size(bits);
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struct bitfield *bitfield;
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bitfield = mem_calloc(1, offsetof(struct bitfield, bits) + size);
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if (bitfield) bitfield->bitsize = bits;
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return bitfield;
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}
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/* Update @bitfield with the @size bytes from the @bits string in @bits. */
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static inline void
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copy_bitfield(struct bitfield *bitfield,
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const unsigned char *bits, unsigned int bytesize)
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{
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/* Only for exact size? */
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if (bytesize <= get_bitfield_byte_size(bitfield->bitsize))
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memcpy(bitfield->bits, bits, bytesize);
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}
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/* Test whether @bit is set in the bitfield. */
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static inline int
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test_bitfield_bit(struct bitfield *bitfield, unsigned int bit)
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{
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size_t byte_offset, bit_offset;
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if (bit >= bitfield->bitsize)
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return 0;
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byte_offset = get_bitfield_byte_offset(bit);
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bit_offset = get_bitfield_bit_offset(bit);
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return !!(bitfield->bits[byte_offset] & bit_offset);
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}
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/* Set @bit in the bitfield. */
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static inline void
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set_bitfield_bit(struct bitfield *bitfield, unsigned int bit)
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{
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size_t byte_offset, bit_offset;
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if (bit >= bitfield->bitsize)
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return;
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byte_offset = get_bitfield_byte_offset(bit);
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bit_offset = get_bitfield_bit_offset(bit);
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bitfield->bits[byte_offset] |= bit_offset;
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}
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/* Unset @bit in the bitfield. */
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static inline void
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clear_bitfield_bit(struct bitfield *bitfield, unsigned int bit)
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{
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size_t byte_offset, bit_offset;
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if (bit >= bitfield->bitsize)
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return;
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byte_offset = get_bitfield_byte_offset(bit);
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bit_offset = get_bitfield_bit_offset(bit);
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bitfield->bits[byte_offset] &= ~bit_offset;
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}
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static inline unsigned int
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get_bitfield_set_count(struct bitfield *bitfield)
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{
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unsigned int bit, count = 0;
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foreach_bitfield_set (bit, bitfield)
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count++;
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return count;
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}
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static inline unsigned int
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get_bitfield_cleared_count(struct bitfield *bitfield)
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{
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unsigned int bit, count = 0;
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foreach_bitfield_cleared (bit, bitfield)
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count++;
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return count;
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}
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static inline unsigned int
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bitfield_is_set(struct bitfield *bitfield)
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{
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unsigned int bit;
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foreach_bitfield_cleared (bit, bitfield)
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return 0;
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return 1;
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}
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static inline unsigned int
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bitfield_is_cleared(struct bitfield *bitfield)
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{
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unsigned int bit;
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foreach_bitfield_set (bit, bitfield)
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return 0;
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return 1;
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}
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#endif
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