hashmapp/hashmap.c

#include "hashmap.h"
#include <stdio.h>
#include <string.h>

void init_map(HashMap *map) {
    memset(map, 0, sizeof(HashMap));
}

long long hash(const char *s) {
    const int p = 100;
    const int m = 1e9 + 9;
    long p_pow = 1;
    long value = 0;
    const unsigned long len = strlen(s);
    for (unsigned long i = 0; i < len; i++) {
        unsigned char c = s[i];
        value = (value + (c - 'a' + 1) * p_pow) % m;
        p_pow = (p_pow * p) % m;
    }
    return value;
}

void *map_get(HashMap *map, char *key) {
    Bucket *bucket = &map->buckets[hash(key) % HASHMAP_BUCKETS];
    Entry *entry = NULL;

    for (size_t i = 0; i < bucket->n_entries; i++) {
        if (!strcmp(bucket->entries[i].key, key))
            return bucket->entries[i].data;
    }

    return NULL;
}

Entry *map_set(HashMap *map, char *key, void *data, size_t data_size) {
    Bucket *bucket = &map->buckets[hash(key) % HASHMAP_BUCKETS];
    Entry *entry = NULL;

    size_t i = 0;
    for (; i < bucket->n_entries; i++) {
        entry = &bucket->entries[i];
        if (!strcmp(entry->key, key)) {
            // entry exists; replace data
            entry->data = data;
            return entry;
        }
    }

    // entry doesn't exist; insert data
    if (i >= BUCKET_ENTRIES) {
        fprintf(stderr, "set \"%s\": bucket is full\n", key);
        return NULL;
    }

    entry = &bucket->entries[i];
    entry->key = strdup(key);
    entry->data = data;
    entry->data_size = data_size;
    bucket->n_entries++;
    return entry;
}