Userspace incremental-only heap implementation

[MartinUbl]

The task here is to implement a heap for userspace. Every process may request an arbitrary amount of heap memory. The heap must be incremental-only; thus, no deallocation is required, only allocation.

The implementor is required to reduce the number of system calls for allocations, utilizing a standard library implementation of his/her own making. A simple way of achieving the reduction could be demonstrated as follows:

char* a = malloc(10); // user code requests 10 bytes, however, standard library pre-allocates 128 bytes - SYSCALL occurs
char* b = malloc(20); // user code requests 20 bytes, standard library still has 118 bytes left - no syscall
char *c = malloc(90); // user code requests 100 bytes, standard library still has 98 bytes left - no syscall
char *d = malloc(10); // user code requests 10 bytes, standard library has only 8 bytes left - SYSCALL occurs
// etc.

Thus, the implementor must implement:

• syscalls for heap allocation (may be brk and sbrk, or a completely different approach)
• syscall stub in userspace RTL
• malloc() standard library implementation with at least a simple way of reducing system calls