Removing '__RemoveNode' (#935)

Replaced '__RemoveNode' as it was causing invalid memory accesses with regular doubly linked list deletion algorithm.
Replaced double pointer iterator in 'MemPoolAlloc' with single pointer iterator.
Fixed undefined variables errors in 'MemPoolFree' for the freelist bucket.

src/rmem.h

@@ -5,7 +5,7 @@
 *   A quick, efficient, and minimal free list and stack-based allocator
 *
 *   PURPOSE:
-*     - Aquicker, efficient memory allocator alternative to 'malloc' and friends.
+*     - A quicker, efficient memory allocator alternative to 'malloc' and friends.
 *     - Reduce the possibilities of memory leaks for beginner developers using Raylib.
 *     - Being able to flexibly range check memory if necessary.
 *
@@ -168,21 +168,6 @@ static inline size_t __AlignSize(const size_t size, const size_t align)
     return (size + (align - 1)) & -align;
 }
 
-static void __RemoveNode(MemPool *const mempool, MemNode **const node)
-{
-    if ((*node)->next != NULL) (*node)->next->prev = (*node)->prev;
-    else {
-        mempool->freeList.tail = (*node)->prev;
-        if (mempool->freeList.tail != NULL) mempool->freeList.tail->next = NULL;
-    }
-    
-    if ((*node)->prev != NULL) (*node)->prev->next = (*node)->next;
-    else {
-        mempool->freeList.head = (*node)->next;
-        if (mempool->freeList.head != NULL) mempool->freeList.head->prev = NULL;
-    }
-}
-
 //----------------------------------------------------------------------------------
 // Module Functions Definition - Memory Pool
 //----------------------------------------------------------------------------------
@@ -244,6 +229,7 @@ void *MemPoolAlloc(MemPool *const mempool, const size_t size)
         const size_t ALLOC_SIZE = __AlignSize(size + sizeof *new_mem, sizeof(intptr_t));
         const size_t BUCKET_INDEX = (ALLOC_SIZE >> MEMPOOL_BUCKET_BITS) - 1;
         
+        // If the size is small enough, let's check if our buckets has a fitting memory block.
         if (BUCKET_INDEX < MEMPOOL_BUCKET_SIZE && mempool->buckets[BUCKET_INDEX] != NULL && mempool->buckets[BUCKET_INDEX]->size >= ALLOC_SIZE)
         {
             new_mem = mempool->buckets[BUCKET_INDEX];
@@ -256,22 +242,28 @@ void *MemPoolAlloc(MemPool *const mempool, const size_t size)
             const size_t MEM_SPLIT_THRESHOLD = 16;
             
             // If the freelist is valid, let's allocate FROM the freelist then!
-            for (MemNode **inode = &mempool->freeList.head; *inode != NULL; inode = &(*inode)->next)
+            for (MemNode *inode = mempool->freeList.head; inode != NULL; inode = inode->next)
             {
-                if ((*inode)->size < ALLOC_SIZE) continue;
-                else if ((*inode)->size <= (ALLOC_SIZE + MEM_SPLIT_THRESHOLD))
+                if (inode->size < ALLOC_SIZE) continue;
+                else if (inode->size <= (ALLOC_SIZE + MEM_SPLIT_THRESHOLD))
                 {
                     // Close in size - reduce fragmentation by not splitting.
-                    new_mem = *inode;
-                    __RemoveNode(mempool, inode);
+                    new_mem = inode;
+                    (inode->prev != NULL)? (inode->prev->next = inode->next) : (mempool->freeList.head = inode->next);
+                    (inode->next != NULL)? (inode->next->prev = inode->prev) : (mempool->freeList.tail = inode->prev);
+                    
+                    if (mempool->freeList.head != NULL) mempool->freeList.head->prev = NULL;
+                    else mempool->freeList.tail = NULL;
+                    
+                    if (mempool->freeList.tail != NULL) mempool->freeList.tail->next = NULL;
                     mempool->freeList.len--;
                     break;
                 }
                 else
                 {
                     // Split the memory chunk.
-                    new_mem = (MemNode *)((uint8_t *)*inode + ((*inode)->size - ALLOC_SIZE));
-                    (*inode)->size -= ALLOC_SIZE;
+                    new_mem = (MemNode *)((uint8_t *)inode + (inode->size - ALLOC_SIZE));
+                    inode->size -= ALLOC_SIZE;
                     new_mem->size = ALLOC_SIZE;
                     break;
                 }
@@ -356,13 +348,13 @@ void MemPoolFree(MemPool *const restrict mempool, void *ptr)
         // attempted stack merge failed, try to place it into the memnode buckets
         else if (BUCKET_INDEX < MEMPOOL_BUCKET_SIZE)
         {
-            if (mempool->buckets[index] == NULL) mempool->buckets[index] = node;
+            if (mempool->buckets[BUCKET_INDEX] == NULL) mempool->buckets[BUCKET_INDEX] = mem_node;
             else
             {
-                for (MemNode *n = mempool->buckets[index]; n != NULL; n = n->next) if( n==node ) return;
-                mempool->buckets[index]->prev = node;
-                node->next = mempool->buckets[index];
-                mempool->buckets[index] = node;
+                for (MemNode *n = mempool->buckets[BUCKET_INDEX]; n != NULL; n = n->next) if( n==mem_node ) return;
+                mempool->buckets[BUCKET_INDEX]->prev = mem_node;
+                mem_node->next = mempool->buckets[BUCKET_INDEX];
+                mempool->buckets[BUCKET_INDEX] = mem_node;
             }
         }
         // Otherwise, we add it to the free list.
@@ -459,7 +451,13 @@ bool MemPoolDefrag(MemPool *const mempool)
                     // If node is right at the stack, merge it back into the stack.
                     mempool->stack.base += (*node)->size;
                     (*node)->size = 0UL;
-                    __RemoveNode(mempool, node);
+                    ((*node)->prev != NULL)? ((*node)->prev->next = (*node)->next) : (mempool->freeList.head = (*node)->next);
+                    ((*node)->next != NULL)? ((*node)->next->prev = (*node)->prev) : (mempool->freeList.tail = (*node)->prev);
+                    
+                    if (mempool->freeList.head != NULL) mempool->freeList.head->prev = NULL;
+                    else mempool->freeList.tail = NULL;
+                    
+                    if (mempool->freeList.tail != NULL) mempool->freeList.tail->next = NULL;
                     mempool->freeList.len--;
                     node = &mempool->freeList.head;
                 }