Dynamic memory allocator

This project implements a custom dynamic memory allocator in C, replicating the functionality of the standard malloc and free. It manages a heap memory pool using an implicit free list structure with specific optimizations for memory utilization.

Key Features

• Implicit Free List: Uses a linear heap structure to track allocated and free blocks.
• First Fit Policy: Searches for the first available free block that fits the requested size.
• Immediate Coalescing: Merges adjacent free blocks immediately upon freeing to minimize external fragmentation.
• Boundary Tag Optimization (Footer Removal): Allocated blocks do not store a footer (boundary tag). This saves 4 bytes (on 32-bit) or 8 bytes (on 64-bit) per allocation, improving memory utilization.
• 2-Bit Tagging System: The block header uses the lowest 2 bits to store allocation status:
  • Bit 0: Current block allocation status (0: Free, 1: Allocated).
  • Bit 1: Previous block allocation status (0: Free, 1: Allocated).

File Structure

• malloc.c: Main source code containing the allocator implementation and a test driver (main function).

Functions

• mm_init(): Initializes the heap model, creating prologue and epilogue blocks.
• mm_alloc(size_t size): Allocates a block of at least size bytes.
• mm_free(void *ptr): Frees the block pointed to by ptr and coalesces it with neighbors if possible.
• show_mm(): A utility function that traverses the heap and prints the status of every block (header, footer, size, flags) for debugging purposes.

How to Compile and Run

This project can be compiled using gcc.

Build

gcc -o malloc malloc.c

Run

./malloc