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use std::alloc::Layout;
use std::ptr;
use crate::data_structs::bitmap::consts::{DIV_SHIFT, MASK};

#[cfg(target_pointer_width = "64")]
pub(crate) mod consts{
    pub(crate) const DIV_SHIFT: usize = 6;
    pub(crate) const MASK: usize = 63;
}

#[cfg(target_pointer_width = "32")]
pub(self) mod consts{
    pub(crate) const DIV_SHIFT: usize = 5;
    pub(crate) const MASK: usize = 31;
}
#[cfg(target_pointer_width = "16")]
pub(self) mod consts{
    pub(crate) const DIV_SHIFT: usize = 4;
    pub(crate) const MASK: usize = 15;
}

#[cfg(target_pointer_width = "8")]
pub(self) mod consts{
    pub(crate) const DIV_SHIFT: usize = 3;
    pub(crate) const MASK: usize = 7;
}



pub struct Bitmap {
    data: *mut usize,
    bit_capacity: usize,
    capacity: usize,
    layout: Layout
}

impl Bitmap
{
    pub fn new(bit_count: usize) -> Self {
        let size = (bit_count >> DIV_SHIFT) + 1;
        let layout = Layout::array::<usize>(size).expect("Failed to create layout");
        let data = unsafe { std::alloc::alloc(layout) as *mut usize };
        unsafe {ptr::write_bytes(data, 0, size)};
        Bitmap {
            data,
            capacity: size,
            bit_capacity: bit_count,
            layout
        }
    }
    #[inline(always)]
    pub fn bit_capacity(&self) -> usize {
        self.bit_capacity
    }
    #[inline(always)]
    pub fn capacity(&self) -> usize {
        self.capacity
    }
    #[inline(always)]
    pub fn set(&mut self, bit_index: usize, value: bool) {
        if bit_index >= self.bit_capacity {
            panic!("Bit index out of bounds");
        }

        let offset = bit_index >> DIV_SHIFT;
        let bit_offset = bit_index & (MASK);
        unsafe {
            let ptr = self.data.add(offset);
            *ptr = (*ptr & !(1 << bit_offset)) | ((value as usize) << bit_offset);
        }
    }
    #[inline(always)]
    pub fn get(&self, bit_index: usize) -> Option<bool> {
        if bit_index >= self.bit_capacity {
            return None;
        }

        let offset = bit_index >> DIV_SHIFT;
        let bit_offset = bit_index & (MASK);
        unsafe {
            let ptr = self.data.add(offset);
            Some((*ptr & (1 << bit_offset)) != 0)
        }
    }
    #[inline(always)]
    pub unsafe fn set_unchecked(&mut self, bit_index: usize, value: bool) {
        let offset = bit_index >> DIV_SHIFT;
        let bit_offset = bit_index & (MASK);
        unsafe {
            let ptr = self.data.add(offset);
            *ptr = (*ptr & !(1 << bit_offset)) | ((value as usize) << bit_offset);
        }
    }
    #[inline(always)]
    pub unsafe fn get_unchecked(&self, bit_index: usize) -> bool {
        let offset = bit_index >> DIV_SHIFT;
        let bit_offset = bit_index & (MASK);
        unsafe {
            let ptr = self.data.add(offset);
            (*ptr & (1 << bit_offset)) != 0
        }
    }
}

impl Drop for Bitmap {
    fn drop(&mut self) {
        unsafe {
            std::alloc::dealloc(self.data as *mut u8, self.layout);
        }
    }
}