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80 lines
1.4 KiB
C
80 lines
1.4 KiB
C
/*
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* BIRD Library -- ID Map
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*
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* (c) 2013--2015 Ondrej Zajicek <santiago@crfreenet.org>
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* (c) 2013--2015 CZ.NIC z.s.p.o.
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*/
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#include <stdlib.h>
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#include "nest/bird.h"
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#include "lib/idm.h"
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#include "lib/resource.h"
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#include "lib/string.h"
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void
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idm_init(struct idm *m, pool *p, u64 size, u64 max)
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{
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m->pos = 0;
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m->used = 1;
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m->size = size;
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m->max = max;
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m->data = mb_allocz(p, m->size * sizeof(u32));
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/* ID 0 is reserved */
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m->data[0] = 1;
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}
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static inline int u32_cto(uint x) { return ffs(~x) - 1; }
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u64
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idm_alloc(struct idm *m)
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{
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u64 i, j;
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for (i = m->pos; i < m->size; i++)
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if (m->data[i] != 0xffffffff)
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goto found;
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/* If we are at least 7/8 full, expand (if we are allowed to) */
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if ((m->used < m->max) && (m->used > m->size * 28))
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{
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m->size *= 2;
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m->data = mb_realloc(m->data, m->size * sizeof(u32));
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memset(m->data + i, 0, (m->size - i) * sizeof(u32));
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goto found;
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}
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for (i = 0; i < m->pos; i++)
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if (m->data[i] != 0xffffffff)
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goto found;
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return 0;
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found:
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m->pos = i;
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j = u32_cto(m->data[i]);
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u64 id = 32 * i + j;
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ASSERT(id < m->max);
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m->data[i] |= (1 << j);
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m->used++;
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return id;
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}
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void
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idm_free(struct idm *m, u64 id)
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{
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u64 i = id / 32;
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u64 j = id % 32;
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ASSERT((i < m->size) && (m->data[i] & (1 << j)));
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m->data[i] &= ~(1 << j);
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m->used--;
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}
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