git init

1 files changed, 99 insertions, 0 deletions

diff --git a/src/hash_table.c b/src/hash_table.c
new file mode 100644
index 0000000..3b635f4
--- /dev/null
+++ b/src/hash_table.c
@@ -0,0 +1,99 @@
+#include "hash_table.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#define HTFL_NUL 0
+#define HTFL_VAL 1
+#define HTFL_DEL 2
+
+static void *hash_table_end(hash_table_t *ht) {
+    return ht->buf + ht->cap * (ht->elemsz + 1);
+}
+
+static void rebuild(hash_table_t *ht) {
+    hash_table_t newht;
+    init_hash_table(&newht, ht->elemsz, ht->size * 6, ht->hash, ht->eq);
+    void *iter = hash_table_begin(ht);
+    while (iter != NULL) {
+        hash_table_insert(&newht, iter);
+        iter = hash_table_next(ht, iter);
+    }
+    free(ht->buf);
+    *ht = newht;
+}
+
+static uint8_t getflag(void *iter) { return *(uint8_t *)(iter - 1); }
+
+static void setflag(void *iter, uint8_t flag) { *(uint8_t *)(iter - 1) = flag; }
+
+void init_hash_table(hash_table_t *ht, int64_t elemsz, int64_t cap,
+                     uint64_t (*hash)(void *), bool (*eq)(void *, void *)) {
+    if (cap < 16) cap = 16;
+    ht->buf = malloc(cap * (elemsz + 1));
+    memset(ht->buf, 0, cap * (elemsz + 1));
+    ht->size = 0;
+    ht->cap = cap;
+    ht->taken = 0;
+    ht->begin = NULL;
+    ht->elemsz = elemsz;
+    ht->hash = hash;
+    ht->eq = eq;
+}
+
+bool hash_table_insert(hash_table_t *ht, void *elem) {
+    if (ht->taken + 1 > ht->cap / 2) {
+        rebuild(ht);
+    }
+    ht->taken++;
+    ht->size++;
+    int64_t hashcode = ht->hash(elem) % ht->cap;
+    void *pos = ht->buf + hashcode * (ht->elemsz + 1) + 1;
+    while (getflag(pos) != HTFL_NUL) {
+        if (getflag(pos) == HTFL_VAL && ht->eq(pos, elem)) return false;
+        pos += ht->elemsz + 1;
+        if (pos >= hash_table_end(ht)) { // arrived end, restart from beginning
+            pos = ht->buf + 1;
+        }
+    }
+    memcpy(pos, elem, ht->elemsz);
+    setflag(pos, HTFL_VAL);
+    if (pos < ht->begin || ht->begin == NULL) {
+        ht->begin = pos;
+    }
+    return true;
+}
+
+void hash_table_remove(hash_table_t *ht, void *iter) {
+    ht->size--;
+    setflag(iter, HTFL_DEL);
+    if (iter == ht->begin) {
+        ht->begin = hash_table_next(ht, iter);
+    }
+}
+
+void *hash_table_find(hash_table_t *ht, void *elem) {
+    int64_t hashcode = ht->hash(elem) % ht->cap;
+    void *pos = ht->buf + hashcode * (ht->elemsz + 1) + 1;
+    while (getflag(pos) != HTFL_NUL) {
+        if (getflag(pos) == HTFL_VAL && ht->eq(pos, elem)) return pos;
+        pos += ht->elemsz + 1;
+        if (pos >= hash_table_end(ht)) { // arrived end, restart from beginning
+            pos = ht->buf + 1;
+        }
+    }
+    return NULL;
+}
+
+void *hash_table_begin(hash_table_t *ht) { return ht->begin; }
+
+void *hash_table_next(hash_table_t *ht, void *iter) {
+    void *pos = iter;
+    do {
+        pos += ht->elemsz + 1;
+        if (pos >= hash_table_end(ht)) {
+            return NULL;
+        }
+    } while (getflag(pos) != HTFL_VAL);
+    return pos;
+}