*
********************************************************/
-#include "utils.h"
+#include "config.h"
+
+#include <assert.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <string.h>
+
#include "atom.h"
+#include "darray.h"
+#include "utils.h"
-struct atom_node {
- xkb_atom_t left, right;
- unsigned int fingerprint;
- char *string;
-};
+/* FNV-1a (http://www.isthe.com/chongo/tech/comp/fnv/). */
+static inline uint32_t
+hash_buf(const char *string, size_t len)
+{
+ uint32_t hash = 2166136261u;
+ for (size_t i = 0; i < (len + 1) / 2; i++) {
+ hash ^= (uint8_t) string[i];
+ hash *= 0x01000193;
+ hash ^= (uint8_t) string[len - 1 - i];
+ hash *= 0x01000193;
+ }
+ return hash;
+}
+/*
+ * The atom table is an insert-only linear probing hash table
+ * mapping strings to atoms. Another array maps the atoms to
+ * strings. The atom value is the position in the strings array.
+ */
struct atom_table {
- xkb_atom_t root;
- darray(struct atom_node) table;
+ xkb_atom_t *index;
+ size_t index_size;
+ darray(char *) strings;
};
struct atom_table *
atom_table_new(void)
{
- struct atom_table *table;
-
- table = calloc(1, sizeof(*table));
+ struct atom_table *table = calloc(1, sizeof(*table));
if (!table)
return NULL;
- darray_init(table->table);
- /* The original throw-away root is here, at the illegal atom 0. */
- darray_resize0(table->table, 1);
+ darray_init(table->strings);
+ darray_append(table->strings, NULL);
+ table->index_size = 4;
+ table->index = calloc(table->index_size, sizeof(*table->index));
return table;
}
void
atom_table_free(struct atom_table *table)
{
- struct atom_node *node;
-
if (!table)
return;
- darray_foreach(node, table->table)
- free(node->string);
- darray_free(table->table);
+ char **string;
+ darray_foreach(string, table->strings)
+ free(*string);
+ darray_free(table->strings);
+ free(table->index);
free(table);
}
const char *
atom_text(struct atom_table *table, xkb_atom_t atom)
{
- if (atom == XKB_ATOM_NONE || atom >= darray_size(table->table))
- return NULL;
-
- return darray_item(table->table, atom).string;
+ assert(atom < darray_size(table->strings));
+ return darray_item(table->strings, atom);
}
-static bool
-find_atom_pointer(struct atom_table *table, const char *string, size_t len,
- xkb_atom_t **atomp_out, unsigned int *fingerprint_out)
+xkb_atom_t
+atom_intern(struct atom_table *table, const char *string, size_t len, bool add)
{
- xkb_atom_t *atomp = &table->root;
- unsigned int fingerprint = 0;
- bool found = false;
-
- for (size_t i = 0; i < (len + 1) / 2; i++) {
- fingerprint = fingerprint * 27 + string[i];
- fingerprint = fingerprint * 27 + string[len - 1 - i];
- }
-
- while (*atomp != XKB_ATOM_NONE) {
- struct atom_node *node = &darray_item(table->table, *atomp);
-
- if (fingerprint < node->fingerprint) {
- atomp = &node->left;
- }
- else if (fingerprint > node->fingerprint) {
- atomp = &node->right;
- }
- else {
- /* Now start testing the strings. */
- const int cmp = strncmp(string, node->string, len);
- if (cmp < 0 || (cmp == 0 && node->string[len] != '\0')) {
- atomp = &node->left;
- }
- else if (cmp > 0) {
- atomp = &node->right;
- }
- else {
- found = true;
- break;
+ if (darray_size(table->strings) > 0.80 * table->index_size) {
+ table->index_size *= 2;
+ table->index = realloc(table->index, table->index_size * sizeof(*table->index));
+ if (!table->index)
+ return XKB_ATOM_NONE;
+
+ memset(table->index, 0, table->index_size * sizeof(*table->index));
+ for (size_t j = 1; j < darray_size(table->strings); j++) {
+ const char *s = darray_item(table->strings, j);
+ uint32_t hash = hash_buf(s, strlen(s));
+ for (size_t i = 0; i < table->index_size; i++) {
+ size_t index_pos = (hash + i) & (table->index_size - 1);
+ if (index_pos == 0)
+ continue;
+
+ xkb_atom_t atom = table->index[index_pos];
+ if (atom == XKB_ATOM_NONE) {
+ table->index[index_pos] = j;
+ break;
+ }
}
}
}
- if (fingerprint_out)
- *fingerprint_out = fingerprint;
- if (atomp_out)
- *atomp_out = atomp;
- return found;
-}
-
-xkb_atom_t
-atom_lookup(struct atom_table *table, const char *string, size_t len)
-{
- xkb_atom_t *atomp;
-
- if (!string)
- return XKB_ATOM_NONE;
-
- if (!find_atom_pointer(table, string, len, &atomp, NULL))
- return XKB_ATOM_NONE;
-
- return *atomp;
-}
-
-xkb_atom_t
-atom_intern(struct atom_table *table, const char *string, size_t len)
-{
- xkb_atom_t *atomp;
- struct atom_node node;
- unsigned int fingerprint;
-
- if (!string)
- return XKB_ATOM_NONE;
+ uint32_t hash = hash_buf(string, len);
+ for (size_t i = 0; i < table->index_size; i++) {
+ size_t index_pos = (hash + i) & (table->index_size - 1);
+ if (index_pos == 0)
+ continue;
+
+ xkb_atom_t existing_atom = table->index[index_pos];
+ if (existing_atom == XKB_ATOM_NONE) {
+ if (add) {
+ xkb_atom_t new_atom = darray_size(table->strings);
+ darray_append(table->strings, strndup(string, len));
+ table->index[index_pos] = new_atom;
+ return new_atom;
+ } else {
+ return XKB_ATOM_NONE;
+ }
+ }
- if (find_atom_pointer(table, string, len, &atomp, &fingerprint)) {
- return *atomp;
+ const char *existing_value = darray_item(table->strings, existing_atom);
+ if (strncmp(existing_value, string, len) == 0 && existing_value[len] == '\0')
+ return existing_atom;
}
- node.string = strndup(string, len);
- if (!node.string)
- return XKB_ATOM_NONE;
-
- node.left = node.right = XKB_ATOM_NONE;
- node.fingerprint = fingerprint;
- xkb_atom_t atom = darray_size(table->table);
- /* Do this before the append, as it may realloc and change the offsets. */
- *atomp = atom;
- darray_append(table->table, node);
-
- return atom;
+ assert(!"couldn't find an empty slot during probing");
}
projects / platform / upstream / libxkbcommon.git / blobdiff