Malloc Visualizer

A web-based visualizer for dynamic memory allocation in C-style heaps. This interactive tool demonstrates how malloc, free, and realloc work, including allocation, splitting, coalescing, and alignment.

🔹 Demo

Hover over blocks to view metadata and payload information. Click on a block to select its payload pointer for freeing or reallocating.

Animation Speed: Adjustable via the slider to control visualization speed.

⚙️ Key Features

Dynamic Allocation: malloc allocates memory blocks with first-fit strategy.
Freeing & Reallocation: free and realloc work on the visible payload pointer.
Alignment: All allocations are aligned to 16 bytes for proper memory alignment.
Metadata: Each block contains 16 bytes of metadata (shown for educational purposes) and is tracked with boundary tags.
Doubly Linked List: Blocks are stored in a doubly linked list to facilitate coalescing and splitting.
Explicit Free List: Free blocks are tracked in a separate list for efficient allocation.
Animations: Animated allocation, split, and coalescing to visually demonstrate memory operations.
Interactive: Hover for details, click to select payload pointers.

📝 Assumptions

16-byte alignment for all allocations.
Metadata is 16 bytes per block.
First-fit allocation strategy.
Blocks are doubly linked with boundary tags.
Explicit free list is used for free blocks.
Most recently freed block is the head of the free linked list.
Splitting and coalescing are visualized.

🎮 How to Use

Enter the allocation size and click malloc.
Hover over blocks to see:
- Metadata pointer
- Payload pointer
- Total block size
Click a block to select its payload pointer.
Enter the pointer in the input field to:
- free a block
- realloc a block to a new size
Use the animation speed slider to adjust visualization speed (in milliseconds per step). Higher value = slower animations.
Invalid operations (double free, negative sizes, invalid pointers) trigger error messages via toast notifications.
Alignment adjustments show info to indicate requested vs aligned size.

⚡ Implementation Details

Heap Representation: A single linked list of Block objects with prev_phys and next_phys pointers.
Free List: Blocks marked as free are maintained in a separate explicit free list (prev_free, next_free).
Allocation:
- If a free block fits, it is reused and split if large enough.
- Otherwise, the heap grows by creating a new block.
Deallocation:
- Frees the block and coalesces adjacent free blocks.
Reallocation:
- Shrinks blocks in place when possible.
- Expands into neighboring right free block if available.
- Otherwise, allocates a new block and frees the old one.
User Interaction:
- Only the payload pointer is used for free and realloc.
- Metadata pointer is internal, only being shown in the free list and when hovering on the blocks for educational purposes.

🎨 UI Highlights

Color Coding:
- Allocated: Blue
- Free: Red
- Split Highlight: Cyan
- Coalesce Highlight: Green
- Search/Allocation: Yellow/Orange
Tooltips: Show block metadata and size.
Animations: Smooth transitions for allocation, splitting, and coalescing.