// This file is part of libfringe, a low-level green threading library.
// Copyright (c) whitequark <whitequark@whitequark.org>
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.
#![feature(alloc, heap_api, allocator_api)]

extern crate alloc;
extern crate fringe;

use alloc::heap::Heap;
use alloc::allocator::{Alloc, Layout};
use alloc::boxed::Box;
use std::slice;
use fringe::{STACK_ALIGNMENT, Stack, SliceStack, OwnedStack, OsStack};

unsafe fn heap_allocate(size: usize, align: usize) -> *mut u8 {
  Heap.alloc(Layout::from_size_align_unchecked(size, align)).expect("couldn't allocate")
}

#[test]
fn slice_aligned() {
  unsafe {
    let ptr = heap_allocate(16384, STACK_ALIGNMENT);
    let mut slice = Box::from_raw(slice::from_raw_parts_mut(ptr, 16384));
    let stack = SliceStack::new(&mut slice[4096..8192]);
    assert_eq!(stack.base() as usize & (STACK_ALIGNMENT - 1), 0);
    assert_eq!(stack.limit() as usize & (STACK_ALIGNMENT - 1), 0);
  }
}

#[test]
fn slice_unaligned() {
  unsafe {
    let ptr = heap_allocate(16384, STACK_ALIGNMENT);
    let mut slice = Box::from_raw(slice::from_raw_parts_mut(ptr, 16384));
    let stack = SliceStack::new(&mut slice[4097..8193]);
    assert_eq!(stack.base() as usize & (STACK_ALIGNMENT - 1), 0);
    assert_eq!(stack.limit() as usize & (STACK_ALIGNMENT - 1), 0);
  }
}

#[test]
fn slice_too_small() {
  unsafe {
    let ptr = heap_allocate(STACK_ALIGNMENT, STACK_ALIGNMENT);
    let mut slice = Box::from_raw(slice::from_raw_parts_mut(ptr, STACK_ALIGNMENT));
    let stack = SliceStack::new(&mut slice[0..1]);
    assert_eq!(stack.base() as usize & (STACK_ALIGNMENT - 1), 0);
    assert_eq!(stack.limit() as usize & (STACK_ALIGNMENT - 1), 0);
  }
}

#[test]
#[should_panic(expected = "SliceStack too small")]
fn slice_too_small_unaligned() {
  unsafe {
    let ptr = heap_allocate(STACK_ALIGNMENT, STACK_ALIGNMENT);
    let mut slice = Box::from_raw(slice::from_raw_parts_mut(ptr, STACK_ALIGNMENT));
    SliceStack::new(&mut slice[1..2]);
  }
}

#[test]
fn slice_stack() {
  let mut memory = [0; 1024];
  let stack = SliceStack::new(&mut memory);
  assert_eq!(stack.base() as usize & (STACK_ALIGNMENT - 1), 0);
  assert_eq!(stack.limit() as usize & (STACK_ALIGNMENT - 1), 0);

  // Size may be a bit smaller due to alignment
  assert!(stack.base() as usize - stack.limit() as usize > 1024 - STACK_ALIGNMENT * 2);
}

#[test]
fn owned_stack() {
  let stack = OwnedStack::new(1024);
  assert_eq!(stack.base() as usize & (STACK_ALIGNMENT - 1), 0);
  assert_eq!(stack.limit() as usize & (STACK_ALIGNMENT - 1), 0);
  assert_eq!(stack.base() as usize - stack.limit() as usize, 1024);
}

#[test]
fn default_os_stack() {
  let stack = OsStack::new(0).unwrap();
  assert_eq!(stack.base() as usize & (STACK_ALIGNMENT - 1), 0);
  assert_eq!(stack.limit() as usize & (STACK_ALIGNMENT - 1), 0);

  // Make sure the topmost page of the stack, at least, is accessible.
  unsafe { *(stack.base().offset(-1)) = 0; }
}

#[test]
fn one_page_os_stack() {
  let stack = OsStack::new(4096).unwrap();
  assert_eq!(stack.base() as usize & (STACK_ALIGNMENT - 1), 0);
  assert_eq!(stack.limit() as usize & (STACK_ALIGNMENT - 1), 0);

  // Make sure the topmost page of the stack, at least, is accessible.
  unsafe { *(stack.base().offset(-1)) = 0; }
}