🧠 Custom Memory Allocator in C

This project implements a simple, custom memory allocator in C designed for 64-bit systems. It mimics basic heap allocation functionality (similar to malloc and free) within a manually allocated 1GB memory space.

It supports:

• Block-based allocation
• Manual deallocation
• Word-aligned memory (8-byte words)
• Basic memory clearing (zero)
• Heap visualization for debugging

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📦 Features

• ✅ Manual memory allocation & deallocation
• ✅ Fixed-size heap of 1GB (allocated via assembly)
• ✅ Word-based memory management (8 bytes per word)
• ✅ Block splitting to minimize waste
• ✅ Heap visualization to see allocations
• ✅ Simple, menu-based test interface in C

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📂 Project Structure

.
├── allocater.c        # Core allocator implementation
├── allocater.h        # Allocator header definitions
├── heap.asm           # Assembly code allocating 1GB memory
├── Makefile           # (Optional) Build instructions
└── README.md          # Project documentation

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🧠 How It Works

• The memory allocator works on 8-byte words.
• Memory blocks have a header containing:
  • Block size (w in words)
  • Allocation status (alloced)
• Memory operations:
  • Allocate: Finds free block large enough and marks it allocated.
  • Free: Clears memory and marks block as free.
  • Split blocks if a larger-than-needed block is found.

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🏗️ Assembly File: heap.asm

• A custom assembly file is used to reserve a 1GB .bss section:
• This reserved memory acts as the program’s heap space.

⚙️ Build & Run

Build (Example with NASM and GCC):

nasm -f elf64 heap.asm -o heap.o
gcc -o allocator allocater.c heap.o

Or, using a Makefile:

make

Run:

./allocator

🧪 Menu Interface Example

1. Allocate 
2. Destroy
3. Quit

You can:

Allocate memory (input bytes)

Free memory by index

Visualize heap allocations after each operation

🔥 Example Output

Alloc 1 = 2 alloced words
Alloc 2 = 500 alloced words
Alloc 3 = 1 alloced words

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🪄 Known Limitations

No block coalescing after free (no merging of adjacent free blocks yet)

No realloc support

Fixed 1GB heap space (no dynamic resizing)

No thread-safety (single-threaded)

🚀 Possible Improvements

Implement block coalescing after free

Add support for realloc

Better error handling

Optimize allocation search (iterative or free list)

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📝 License

This project is open-source and licensed under the MIT License.

🙌 Contributing

Pull requests and suggestions are welcome!