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#include "tt_treap.h"
// ===================================================================
// Variables
// ===================================================================
uint32_t tt_num_cached;
static tt_entry_t * root;
// ===================================================================
// Helper declarations
// ===================================================================
void recurse_tree(tt_entry_t *n);
tt_entry_t *new_treap_node(const uint64_t key, const enum TT_FLAG flag,
const uint8_t depth, const float value);
void bubble_up(tt_entry_t *n);
// ===================================================================
// Exported functions
// ===================================================================
int tt_init(void) {
root = NULL;
tt_num_cached = 0;
return EXIT_SUCCESS;
}
void tt_free(void) {
recurse_tree(root);
return;
}
tt_entry_t *tt_seek(const uint64_t key) {
if (root == NULL) return NULL;
tt_entry_t * n = root;
while (n != NULL && n->key != key) {
if (n->key > key) n = n->right;
else n = n->left;
}
return n;
}
int tt_insert(const uint64_t key, const enum TT_FLAG flag,
const uint8_t depth, const float value) {
tt_entry_t *m = new_treap_node(key, flag, depth, value);
if (root == NULL) {
root = m;
tt_num_cached = 1;
return EXIT_SUCCESS;
}
tt_entry_t *s = root, *n = root;
// Find the correct position by doing a BST traversal
while (n!=NULL) {
s = n;
if (n->key >= key) n = n->right;
else n = n->left;
}
// Make it a leaf
if (s->key > key) s->right = m;
else s->left = m;
m->parent = s;
// Now bubble upward to satisfy the heap property
bubble_up(m);
tt_num_cached++;
return EXIT_SUCCESS;
}
// ===================================================================
// Helper implementations
// ===================================================================
void recurse_tree(tt_entry_t *n) {
if (n==NULL) return;
if (n->left != NULL) recurse_tree(n->left);
if (n->right != NULL) recurse_tree(n->right);
free(n);
}
tt_entry_t *new_treap_node(const uint64_t key, const enum TT_FLAG flag,
const uint8_t depth, const float value) {
tt_entry_t *n = malloc(sizeof(struct treap_node_s));
// TODO: trap
n->key = key;
n->flag = flag;
n->depth = depth;
n->value = value;
n->left = NULL;
n->right = NULL;
n->parent = NULL;
XORSHIFT64; n->weight = RANDOM32;
return n;
}
void rotate_left(tt_entry_t *n) {
tt_entry_t *a = n->parent, *b = a->left, *c = n->left;
/*
We are the right child, so do this
a n
/ \ / \
b n --> a d
/ \ / \
c d b c
*/
n->parent = a->parent;
// We may have to repair one level up as well
if (a->parent!=NULL) {
if (a->parent->left == a) a->parent->left = n;
else a->parent->right = n;
}
a->parent = n;
n->left = a; a->parent = n;
a->left = b; if (b!=NULL) b->parent = a;
a->right = c; if (c!=NULL) c->parent = a;
}
void rotate_right(tt_entry_t *n) {
tt_entry_t *a = n->parent, *b = a->right, *d = n->right;
/*
We are the left child, so do this
a n
/ \ / \
n b --> c a
/ \ / \
c d d b
*/
n->parent = a->parent;
// We may have to repair one level up as well
if (a->parent!=NULL) {
if (a->parent->left == a) a->parent->left = n;
else a->parent->right = n;
}
a->parent = n;
n->right = a; a->parent = n;
a->left = d; if (d!=NULL) d->parent = a;
a->right = b; if (b!=NULL) b->parent = a;
}
//This preserves the BST quality of the treap
void bubble_up(tt_entry_t *n) {
// Nothing to be done in this case
if (n==NULL || n->parent == NULL) return;
// Bubble until the treap invariants are satisfied
while (n->parent != NULL && n->weight < n->parent->weight) {
if (n->parent->left == n) rotate_right(n);
else rotate_left(n);
}
if (n->parent == NULL) root = n;
}
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