// Copyright 2017 The Australian National University
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::mem;
use utils::POINTER_SIZE;
use utils::LOG_POINTER_SIZE;
use utils::Address;
use utils::mem::malloc_zero;
use utils::mem::memsec::free;

#[derive(Clone)]
pub struct AddressMap<T: Copy> {
    start: Address,
    end: Address,

    pub ptr: *mut T,
    len: usize
}

impl<T> AddressMap<T>
where
    T: Copy
{
    pub fn new(start: Address, end: Address) -> AddressMap<T> {
        let len = (end - start) >> LOG_POINTER_SIZE;
        let ptr = unsafe { malloc_zero(mem::size_of::<T>() * len) } as *mut T;

        AddressMap {
            start: start,
            end: end,
            ptr: ptr,
            len: len
        }
    }

    pub fn init_all(&self, init: T) {
        let mut cursor = self.start;

        while cursor < self.end {
            self.set(cursor, init);
            cursor = cursor + POINTER_SIZE;
        }
    }

    #[inline(always)]
    pub fn set(&self, addr: Address, value: T) {
        let index = ((addr - self.start) >> LOG_POINTER_SIZE) as isize;
        unsafe { *self.ptr.offset(index) = value };
    }

    #[inline(always)]
    pub fn get(&self, addr: Address) -> T {
        let index = ((addr - self.start) >> LOG_POINTER_SIZE) as isize;
        unsafe { *self.ptr.offset(index) }
    }
}

impl<T> Drop for AddressMap<T>
where
    T: Copy
{
    fn drop(&mut self) {
        unsafe { free(self.ptr) }
    }
}