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57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
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/*
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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 fill cb_node.k[] with arbitrary match data
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* for memcmp.
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* If "klen" is variable, then it should be embedded into "c_node.k[]"
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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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#include "git-compat-util.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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uint8_t k[FLEX_ARRAY]; /* arbitrary data */
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};
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struct cb_tree {
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struct cb_node *root;
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};
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enum cb_next {
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CB_CONTINUE = 0,
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CB_BREAK = 1
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};
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#define CBTREE_INIT { .root = NULL }
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static inline void cb_init(struct cb_tree *t)
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{
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t->root = NULL;
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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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struct cb_node *cb_unlink(struct cb_tree *t, const uint8_t *k, size_t klen);
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typedef enum cb_next (*cb_iter)(struct cb_node *, void *arg);
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void 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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