DMA Memory Allocator

A custom dynamic memory allocator written in C using memory-mapped space (mmap) and bitmap tracking. This project demonstrates allocation, deallocation, and internal fragmentation tracking using multithreading.

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📁 Files

• dma.c: Implementation of the dynamic memory allocator.
• dma.h: Header file declaring public DMA functions.
• app.c: Multithreaded test program using the allocator.
• libdma.a: Precompiled static library version of dma.c.
• dma.o: Compiled object file for dma.c.
• Makefile: Compilation instructions.

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🧠 Features

• Custom memory allocator with bitmap-based tracking
• Allocation and deallocation with thread safety
• Tracks internal fragmentation
• Page-level memory inspection
• Allocation block reporting
• Uses mmap() for memory management
• Thread-safe with pthread mutexes

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⚙️ Compilation

Use the provided Makefile to compile everything.

make

This will:

• Compile dma.c into libdma.a

• Compile and link app.c with the library

• Generate the app executable

🚀 Running the Program

To run the multithreaded memory allocator demo:

./app

This will:

• Initialize the memory segment

• Launch 3 threads

• Perform various memory allocations/frees

• Print bitmap and block status

• Report internal fragmentation

🧵 Multithreading

Each thread in app.c does the following:

• Allocates blocks of various sizes

• Frees some of them

• Writes values to allocated blocks (for testing)

• Prints bitmap and block status

• Reports internal fragmentation in that thread

🧪 Diagnostic Tools

• dma_print_bitmap(): Shows the current allocation bitmap.

• dma_print_blocks(): Prints all blocks as Free (F) or Allocated (A).

• dma_print_page(int pno): Prints the hexadecimal content of a page.

• dma_give_intfrag(): Returns the current internal fragmentation value.

🔢 Parameters

• m in dma_init(m) must be between 14 and 22 (inclusive).

• size in dma_alloc(size) is the number of bytes to allocate.

• All allocation sizes are rounded and aligned to match internal block sizes.

🧼 Cleanup

To clean all compiled files:

make clean