xref: /third_party/rust/crates/bindgen/bindgen/codegen/bitfield_unit.rs

#[repr(C)]
#[derive(Copy, Clone, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
pub struct __BindgenBitfieldUnit<Storage> {
    storage: Storage,
}

impl<Storage> __BindgenBitfieldUnit<Storage> {
    #[inline]
    pub const fn new(storage: Storage) -> Self {
        Self { storage }
    }
}

impl<Storage> __BindgenBitfieldUnit<Storage>
where
    Storage: AsRef<[u8]> + AsMut<[u8]>,
{
    #[inline]
    pub fn get_bit(&self, index: usize) -> bool {
        debug_assert!(index / 8 < self.storage.as_ref().len());

        let byte_index = index / 8;
        let byte = self.storage.as_ref()[byte_index];

        let bit_index = if cfg!(target_endian = "big") {
            7 - (index % 8)
        } else {
            index % 8
        };

        let mask = 1 << bit_index;

        byte & mask == mask
    }

    #[inline]
    pub fn set_bit(&mut self, index: usize, val: bool) {
        debug_assert!(index / 8 < self.storage.as_ref().len());

        let byte_index = index / 8;
        let byte = &mut self.storage.as_mut()[byte_index];

        let bit_index = if cfg!(target_endian = "big") {
            7 - (index % 8)
        } else {
            index % 8
        };

        let mask = 1 << bit_index;
        if val {
            *byte |= mask;
        } else {
            *byte &= !mask;
        }
    }

    #[inline]
    pub fn get(&self, bit_offset: usize, bit_width: u8) -> u64 {
        debug_assert!(bit_width <= 64);
        debug_assert!(bit_offset / 8 < self.storage.as_ref().len());
        debug_assert!(
            (bit_offset + (bit_width as usize)) / 8 <=
                self.storage.as_ref().len()
        );

        let mut val = 0;

        for i in 0..(bit_width as usize) {
            if self.get_bit(i + bit_offset) {
                let index = if cfg!(target_endian = "big") {
                    bit_width as usize - 1 - i
                } else {
                    i
                };
                val |= 1 << index;
            }
        }

        val
    }

    #[inline]
    pub fn set(&mut self, bit_offset: usize, bit_width: u8, val: u64) {
        debug_assert!(bit_width <= 64);
        debug_assert!(bit_offset / 8 < self.storage.as_ref().len());
        debug_assert!(
            (bit_offset + (bit_width as usize)) / 8 <=
                self.storage.as_ref().len()
        );

        for i in 0..(bit_width as usize) {
            let mask = 1 << i;
            let val_bit_is_set = val & mask == mask;
            let index = if cfg!(target_endian = "big") {
                bit_width as usize - 1 - i
            } else {
                i
            };
            self.set_bit(index + bit_offset, val_bit_is_set);
        }
    }
}