57 lines
1.7 KiB
C
57 lines
1.7 KiB
C
/*
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* crit-bit tree implementation, does no allocations internally
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* For more information on crit-bit trees: https://cr.yp.to/critbit.html
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* Based on Adam Langley's adaptation of Dan Bernstein's public domain code
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* git clone https://github.com/agl/critbit.git
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*
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* This is adapted to store arbitrary data (not just NUL-terminated C strings
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* and allocates no memory internally. The user needs to allocate
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* "struct cb_node" and provide `key_offset` to indicate where the key can be
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* found relative to the `struct cb_node` for memcmp.
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* If "klen" is variable, then it should be embedded into the key.
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* Recursion is bound by the maximum value of "klen" used.
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*/
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#ifndef CBTREE_H
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#define CBTREE_H
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struct cb_node;
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struct cb_node {
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struct cb_node *child[2];
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/*
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* n.b. uint32_t for `byte' is excessive for OIDs,
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* we may consider shorter variants if nothing else gets stored.
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*/
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uint32_t byte;
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uint8_t otherbits;
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};
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struct cb_tree {
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struct cb_node *root;
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ptrdiff_t key_offset;
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};
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static inline void cb_init(struct cb_tree *t,
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ptrdiff_t key_offset)
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{
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struct cb_tree blank = {
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.key_offset = key_offset,
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};
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memcpy(t, &blank, sizeof(*t));
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}
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struct cb_node *cb_lookup(struct cb_tree *, const uint8_t *k, size_t klen);
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struct cb_node *cb_insert(struct cb_tree *, struct cb_node *, size_t klen);
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/*
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* Callback invoked by `cb_each()` for each node in the critbit tree. A return
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* value of 0 will cause the iteration to continue, a non-zero return code will
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* cause iteration to abort. The error code will be relayed back from
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* `cb_each()` in that case.
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*/
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typedef int (*cb_iter)(struct cb_node *, void *arg);
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int cb_each(struct cb_tree *, const uint8_t *kpfx, size_t klen,
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cb_iter, void *arg);
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#endif /* CBTREE_H */
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