Implemented a simple hash table using the FNV-1a hashing algorithm. Not drawing routines for it yet, just the bare data structure.

includes/hashtable.h

@@ -0,0 +1,25 @@
+#ifndef HASTABLE_H
+#define HASTABLE_H
+
+typedef struct {
+    char* Key;
+    char* Value;
+} BucketKeyPair;
+
+typedef struct {
+    unsigned int Size;
+    unsigned int Capacity;
+    BucketKeyPair** KeyPairs;
+} Bucket;
+
+typedef struct {
+    unsigned int Capacity;
+    Bucket** Values;
+} HashTable;
+
+HashTable* CreateHashTable(void);
+void AddItemToHashTable(char* key, char* item, HashTable* table);
+char* GetHashTableItem(char* key, HashTable* table);
+void PrintHashTable(HashTable* table);
+
+#endif

src/hashtable.c

@@ -0,0 +1,106 @@
+#include "../includes/hashtable.h"
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+//Reference https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash
+//FNV = Fowler–Noll–Vo
+#define FNV_OFFSET 0xcbf29ce484222325 //Or 14695981039346656037 in decimal
+#define FNV_PRIME 0x100000001b3 //Or 1099511628211 in decimal
+#define DEFAULTHASHTABLESIZE 64
+
+Bucket* CreateBucket();
+void AddToBucket(char* key, char* text, Bucket* bucket);
+
+HashTable* CreateHashTable(void) {
+    HashTable* table = calloc(1, sizeof(HashTable));
+
+    table->Values = calloc(DEFAULTHASHTABLESIZE, sizeof(Bucket*));
+    table->Capacity = DEFAULTHASHTABLESIZE;
+    
+    return table;
+}
+
+void AddItemToHashTable(char* key, char* item, HashTable* table) {
+    //FNV-1a hash
+    unsigned long long hash = FNV_OFFSET;
+
+    for(int i = 0; i < strlen(key); i ++) {
+        hash ^= key[i];
+        hash *= FNV_PRIME;
+    }
+
+    unsigned int index = hash % table->Capacity;
+
+    Bucket* bucket = table->Values[index];
+
+    if (!bucket) table->Values[index] = CreateBucket();
+
+    AddToBucket(key, item, table->Values[index]);
+}
+
+char* HashTableBucketLinearScan(char* key, Bucket* bucket) {
+    for(int i = 0; i < bucket->Size; i++) {
+        BucketKeyPair* pair = bucket->KeyPairs[i];
+
+        if (strcmp(key, pair->Key) == 0) return pair->Value;
+    }
+
+    return NULL;
+}
+
+char* GetHashTableItem(char* key, HashTable* table) {
+    unsigned long long hash = FNV_OFFSET;
+
+    for(int i = 0; i < strlen(key); i ++) {
+        hash ^= key[i];
+        hash *= FNV_PRIME;
+    }
+
+    unsigned int index = hash % table->Capacity;
+
+    Bucket* bucket = table->Values[index];
+
+    if (!bucket) return NULL;
+
+    if (bucket->Size == 1) return bucket->KeyPairs[0]->Value;
+
+    return HashTableBucketLinearScan(key, bucket);
+}
+
+Bucket* CreateBucket() {
+    Bucket* bucket = calloc(1, sizeof(Bucket));
+
+    bucket->KeyPairs = calloc(16, sizeof(BucketKeyPair*));
+    bucket->Capacity = 16;
+
+    return bucket;
+}
+
+void AddToBucket(char* key, char* text, Bucket* bucket) {
+    BucketKeyPair* keyPair = calloc(1, sizeof(BucketKeyPair));
+    keyPair->Key = key;
+    keyPair->Value = text;
+
+    bucket->KeyPairs[bucket->Size] = keyPair;
+
+    bucket->Size++;
+}
+
+void PrintHashTable(HashTable* table) {
+    printf("Capacity %d\nBuckets:\n", table->Capacity);
+
+    for(int i = 0; i < table->Capacity; i++) {
+        Bucket* bucket = table->Values[i];
+
+        if (!bucket) continue;
+
+        printf("Bucket %d: \n", i+1);
+
+        for(int j = 0; j < bucket->Size; j++) {
+            printf("(%s) '%s'\n", bucket->KeyPairs[j]->Key, bucket->KeyPairs[j]->Value);
+        }
+
+        printf("\n");
+    }
+}

src/main.c

@@ -19,6 +19,7 @@
 #include <SDL2/SDL_ttf.h>
 #include "../includes/font_cache.h"
 #include "../includes/list.h"
+#include "../includes/hashtable.h"
 
 const int SCREEN_WIDTH = 1280;
 const int SCREEN_HEIGHT = 720;
@@ -131,7 +132,13 @@ int main(int argc, char** argv){
     AddStringToList("Hello World! 4 and a reallly long sting", list);
 
     ListFontSizeHasChanged(app.renderer, GetFont(app.DefaultFontSize, app.FontCache), list);
+    HashTable* table = CreateHashTable();
 
+    AddItemToHashTable("TEST", "Hello, World!", table);
+    AddItemToHashTable("TEST2", "Hello, World", table);
+    AddItemToHashTable("No here", "Hello, 3", table);
+    PrintHashTable(table);
+    printf("Got %s with key %s\n", GetHashTableItem("TEST", table), "TEST");
     // Uint64 start = 0;
     // Uint64 end = 0;
     // float frameCount = 0;