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80 lines
1.3 KiB
C
80 lines
1.3 KiB
C
/*
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* Copyright (C) 2001 Sistina Software (UK) Limited.
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*
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* This file is released under the LGPL.
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*/
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#include "bitset.h"
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#include "dbg_malloc.h"
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#include <stdlib.h>
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/* FIXME: calculate this. */
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#define INT_SHIFT 5
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bitset_t bitset_create(struct pool *mem, unsigned num_bits)
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{
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int n = (num_bits / BITS_PER_INT) + 2;
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int size = sizeof(int) * n;
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unsigned *bs = pool_zalloc(mem, size);
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if (!bs)
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return NULL;
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*bs = num_bits;
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return bs;
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}
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void bitset_destroy(bitset_t bs)
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{
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dbg_free(bs);
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}
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void bit_union(bitset_t out, bitset_t in1, bitset_t in2)
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{
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int i;
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for(i = (in1[0] / BITS_PER_INT) + 1; i; i--)
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out[i] = in1[i] | in2[i];
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}
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/*
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* FIXME: slow
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*/
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static inline int _test_word(uint32_t test, int bit)
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{
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while (bit < BITS_PER_INT) {
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if (test & (0x1 << bit))
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return bit;
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bit++;
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}
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return -1;
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}
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int bit_get_next(bitset_t bs, int last_bit)
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{
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int bit, word;
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uint32_t test;
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last_bit++; /* otherwise we'll return the same bit again */
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while(last_bit < bs[0]) {
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word = last_bit >> INT_SHIFT;
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test = bs[word + 1];
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bit = last_bit & (BITS_PER_INT - 1);
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if ((bit = _test_word(test, bit)) >= 0)
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return (word * BITS_PER_INT) + bit;
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last_bit = last_bit - (last_bit & (BITS_PER_INT - 1)) +
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BITS_PER_INT;
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}
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return -1;
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}
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int bit_get_first(bitset_t bs)
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{
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return bit_get_next(bs, -1);
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}
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