af02b83b88
Basic bitmap is obvious. Hierarchical bitmap is structure of several bitmaps, where higher levels are conjunctions of intervals on level below, allowing for efficient lookup of first unset bit.
190 lines
3.1 KiB
C
190 lines
3.1 KiB
C
/*
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* BIRD Library -- Bitmaps
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*
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* (c) 2019 Ondrej Zajicek <santiago@crfreenet.org>
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* (c) 2019 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/bitmap.h"
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#include "lib/bitops.h"
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#include "lib/resource.h"
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/*
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* Basic bitmap
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*/
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void
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bmap_init(struct bmap *b, pool *p, uint size)
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{
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b->size = BIRD_ALIGN(size, 4);
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b->data = mb_allocz(p, b->size);
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}
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void
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bmap_grow(struct bmap *b, uint need)
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{
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uint size = b->size * 2;
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while (size < need)
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size *= 2;
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uint old_size = b->size;
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b->size = size;
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b->data = mb_realloc(b->data, b->size);
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ASSERT(size >= old_size);
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memset(b->data + (old_size / 4), 0, size - old_size);
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}
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void
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bmap_free(struct bmap *b)
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{
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mb_free(b->data);
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b->size = 0;
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b->data = NULL;
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}
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/*
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* Hierarchical bitmap
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*/
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#define B256_SIZE(b) BIRD_ALIGN(b, 32)
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#define B256_STEP(b) (BIRD_ALIGN(b, 8192) >> 8)
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void
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hmap_init(struct hmap *b, pool *p, uint size)
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{
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b->size[0] = B256_SIZE(size);
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b->size[1] = B256_STEP(b->size[0]);
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b->size[2] = B256_STEP(b->size[1]);
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b->size[3] = sizeof(b->root);
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b->data[0] = mb_allocz(p, b->size[0]);
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b->data[1] = mb_allocz(p, b->size[1]);
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b->data[2] = mb_allocz(p, b->size[2]);
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b->data[3] = b->root;
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memset(b->root, 0, sizeof(b->root));
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}
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static void
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hmap_grow(struct hmap *b, uint need)
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{
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uint size = b->size[0] * 2;
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while (size < need)
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size *= 2;
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for (uint i = 0; i < 3; i++)
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{
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uint old_size = b->size[i];
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b->size[i] = size;
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b->data[i] = mb_realloc(b->data[i], b->size[i]);
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ASSERT(size >= old_size);
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memset(b->data[i] + (old_size / 4), 0, size - old_size);
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size = B256_STEP(size);
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}
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}
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void
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hmap_free(struct hmap *b)
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{
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mb_free(b->data[0]);
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mb_free(b->data[1]);
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mb_free(b->data[2]);
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memset(b, 0, sizeof(struct hmap));
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}
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static inline int
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b256_and(u32 *p)
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{
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for (int i = 0; i < 8; i++)
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if (~p[i])
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return 0;
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return 1;
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}
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void
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hmap_set(struct hmap *b, uint n)
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{
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if (n >= hmap_max(b))
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hmap_grow(b, n/8 + 1);
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for (int i = 0; i < 4; i++)
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{
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BIT32_SET(b->data[i], n);
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n = n >> 8;
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/* Continue if all bits in 256-bit block are set */
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if (! b256_and(b->data[i] + 8*n))
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break;
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}
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}
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void
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hmap_clear(struct hmap *b, uint n)
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{
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if (n >= hmap_max(b))
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return;
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for (int i = 0; i < 4; i++)
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{
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BIT32_CLR(b->data[i], n);
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n = n >> 8;
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}
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}
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static inline int
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b256_first_zero(u32 *p)
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{
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for (int i = 0; i < 8; i++)
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if (~p[i])
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return 32*i + u32_ctz(~p[i]);
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return 256;
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}
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u32
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hmap_first_zero(struct hmap *b)
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{
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u32 n = 0;
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for (int i = 3; i >= 0; i--)
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{
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if (32*n >= b->size[i])
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return hmap_max(b);
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u32 *p = b->data[i] + 8*n;
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n = (n << 8) + b256_first_zero(p);
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}
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return n;
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}
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void
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hmap_check(struct hmap *b)
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{
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for (int i = 0; i < 2; i++)
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{
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int max = b->size[i] / 32;
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for (int j = 0; j < max; j++)
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{
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int x = b256_and(b->data[i] + 8*j);
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int y = !!BIT32_TEST(b->data[i+1], j);
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if (x != y)
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bug("Inconsistent data on %d:%d (%d vs %d)", i, j, x, y);
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}
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}
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}
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