memac: Memory allocator using slab and buddy allocators

Usage

First of all, allocate 64KiB aligned memory regions for slab and buddy allocators.

```rust

![feature(start)]

use memac; use libc::{posixmemalign, cvoid};

[global_allocator]

static mut ALLOC: memac::Allocator = memac::Allocator::new();

fn main() { println!("Hello, world!"); }

const HEAP_SIZE: usize = 32 * 1024 * 1024; // 32MiB

[start]

fn start(argc: isize, _argv: *const *const u8) -> isize { // initialize memory unsafe { // allocate memory let mut ptr: *mut cvoid = std::ptr::nullmut(); if posixmemalign(&mut ptr, memac::ALIGNMENT, HEAPSIZE) != 0 { panic!("posixmemalign"); } ALLOC.init(ptr as usize, HEAP_SIZE); }

main();
0

} ```

toml [dependencies] libc = "0.2" memac = "0.5"

memac::Allocator<memac::budyy::Buddy32M> means that the slab allocator uses the buddy allocator to allocate slabs. If a requested size is greater than (65512 - 8) bytes, the buddy allocator is used to allocate memory.

memac::Allocator<memac::pager::PageManager> means that the allocator uses the page manager to allocate slabs. If a requested size is greater than (65512 - 8) bytes, the page manager is used to allocate memory. If a requested size is greater that 64K bytes, the allocation will fail.