Name: Priscilla Ye
EID: pjy263

How to run build code: ./build.sh

To run: libtdmm.a

# ----- PLANNING -----
Initialization routines
tmalloc()
tfree()
implementation of first fit, best fit, and worst fit
data structure that tracks all currently allocated objects
data structure that tracks all free regions of memory
Statistics gathering models

any pointer that tmalloc returns must be a multiple of 4.

All data structures should be allocated on the region returned by mmap. Usage of libc's malloc is not allowed.

Block Header (Node object).
struct BlockHeader {
    size;
    is_free;
    BlockHeader *next;
    BlockHeader *prev;
}

struct allocatorState {
    strategy;
    BlockHeader* free_list;
    BlockHeader* heap_list;
}

Have a static variable of the allocator state so you don't have to malloc it --> it's a global variable

Initialization routines: sets up allocator state before anything else
- Set strategy of the allocator
- Call mmap to obtain initial heap region:
#include <sys/mman.h>
void mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS, -1, 0)

- cast allocated memory reigon to BlockHeader, size = allocated reigion - BlockHeader, point free_list and heap_list to this block of memory

tmalloc(): returns a pointer to an allocated reigon in memory
- Alignment of memory (must be a multiple of 4): bitshift so requested size is a mulitple of 4.
- Needs to find free locations in memory to allocate (adds to the allocated memory list) --> algorithm is best/first/worst fit. Where the block size is >= size.
- must split a block if the block is larger than the memory size and update pointers & sizes
- If there is not enough space, it must call mmap() --> increases the size of its data segment by allocating more memory.
- Set is_free = 0, return pointer address immediately after the header

tfree():
- Get the header (*block = (BlockHeader*)pter - 1) & mark free
- Merge freed fragments (coalescing)
- Add them to the freed memory list


data structure that tracks all currently allocated objects:
- map of pointer to object size and address
data structure that tracks all free regions of memory:
- linkedlist to track memory locations