David Pitchford 3594118 pitch006

Jacob Wellington 3664486 welli037

CSci 4061 Assignment 3

The purpose of this assignment is to create a memory mananagement system similar to the built-in malloc and free commands. The system also provides memory error-tracking and debugging tools. Currently mm.c can only be used to allocate space for char pointers. Usage is as follows:

int mm_init(unsigned long size); Called by a process using mm.c at the start of its execution. Starts mm.c with a total memory space of size bytes. Returns: 0 on success, -1 on failure.

int mm_end(); Ends the current session with mm.c. Frees all memory allocated by it and prints memory errors that occurred (buffer overflows, free errors, memory leaks). Returns: 0 on success, -1 if called without a corresponding call it mm_init.

char* mm_alloc(unsigned long no_of_chars); Allocates space in mm's memory for a string of length no_of_chars and returns a pointer to the beginning of the space. Returns: A pointer to the allocated memory, or NULL if there is not enough space.

int mm_free(char* ptr); Frees an allocated memory block starting at ptr. Returns: 0 on success, -1 if ptr does not correspond to a previously allocated block or has already been freed.

int mm_assign(char* ptr, char val); Assigns the byte at locartion ptr to val. Will cause a buffer overflow if ptr is not part of an allocated block. Returns: 0 on success, -1 on error.

void mm_barrier_start(); int mm_barrier_end(); These methods provide debugging tools for memory errors. mm_barrier_start creates a memory barrier and mm_barrier_end ends the last created barrier. It also prints out the memory errors that have occurred since the barrier was created (similar to mm_end, but it does not change any allocated blocks). Barriers can be nested. Returns: The total number of memory errors inside the ended barrier. Returns 0 if there have been no errors, or -1 if called without a corresponding call to mm_barrier_start.