Refactor to move alloc_kernel in tree, and move io into syscall

alloc_kernel/src/lib.rs

@@ -0,0 +1,62 @@
+#![feature(allocator)]
+#![feature(const_fn)]
+
+#![allocator]
+#![no_std]
+
+use spin::Mutex;
+use linked_list_allocator::Heap;
+
+extern crate spin;
+extern crate linked_list_allocator;
+
+static HEAP: Mutex<Option<Heap>> = Mutex::new(None);
+
+pub unsafe fn init(offset: usize, size: usize) {
+    *HEAP.lock() = Some(Heap::new(offset, size));
+}
+
+#[no_mangle]
+pub extern fn __rust_allocate(size: usize, align: usize) -> *mut u8 {
+    if let Some(ref mut heap) = *HEAP.lock() {
+        heap.allocate_first_fit(size, align).expect("out of memory")
+    } else {
+        panic!("__rust_allocate: heap not initialized");
+    }
+}
+
+#[no_mangle]
+pub extern fn __rust_deallocate(ptr: *mut u8, size: usize, align: usize) {
+    if let Some(ref mut heap) = *HEAP.lock() {
+        unsafe { heap.deallocate(ptr, size, align) };
+    } else {
+        panic!("__rust_deallocate: heap not initialized");
+    }
+}
+
+#[no_mangle]
+pub extern fn __rust_usable_size(size: usize, _align: usize) -> usize {
+    size
+}
+
+#[no_mangle]
+pub extern fn __rust_reallocate_inplace(_ptr: *mut u8, size: usize,
+    _new_size: usize, _align: usize) -> usize
+{
+    size
+}
+
+#[no_mangle]
+pub extern fn __rust_reallocate(ptr: *mut u8, size: usize, new_size: usize,
+                                align: usize) -> *mut u8 {
+    use core::{ptr, cmp};
+
+    // from: https://github.com/rust-lang/rust/blob/
+    //     c66d2380a810c9a2b3dbb4f93a830b101ee49cc2/
+    //     src/liballoc_system/lib.rs#L98-L101
+
+    let new_ptr = __rust_allocate(new_size, align);
+    unsafe { ptr::copy(ptr, new_ptr, cmp::min(size, new_size)) };
+    __rust_deallocate(ptr, size, align);
+    new_ptr
+}