Function polars_arrow::bit_util::unset_bit_raw

source · 
pub unsafe fn unset_bit_raw(data: *mut u8, i: usize)
Expand description

Sets bit at position i for data to 0

Safety

Note this doesn’t do any bound checking, for performance reason. The caller is responsible to guarantee that i is within bounds.

Examples found in repository?
src/compute/take/mod.rs (line 83)
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pub unsafe fn take_primitive_unchecked<T: NativeType>(
    arr: &PrimitiveArray<T>,
    indices: &IdxArr,
) -> Box<PrimitiveArray<T>> {
    let array_values = arr.values().as_slice();
    let index_values = indices.values().as_slice();
    let validity_values = arr.validity().expect("should have nulls");

    // first take the values, these are always needed
    let values: Vec<T> = index_values
        .iter()
        .map(|idx| {
            debug_assert!((*idx as usize) < array_values.len());
            *array_values.get_unchecked(*idx as usize)
        })
        .collect_trusted();

    // the validity buffer we will fill with all valid. And we unset the ones that are null
    // in later checks
    // this is in the assumption that most values will be valid.
    // Maybe we could add another branch based on the null count
    let mut validity = MutableBitmap::with_capacity(indices.len());
    validity.extend_constant(indices.len(), true);
    let validity_ptr = validity.as_slice().as_ptr() as *mut u8;

    if let Some(validity_indices) = indices.validity().as_ref() {
        index_values.iter().enumerate().for_each(|(i, idx)| {
            // i is iteration count
            // idx is the index that we take from the values array.
            let idx = *idx as usize;
            if !validity_indices.get_bit_unchecked(i) || !validity_values.get_bit_unchecked(idx) {
                unset_bit_raw(validity_ptr, i);
            }
        });
    } else {
        index_values.iter().enumerate().for_each(|(i, idx)| {
            let idx = *idx as usize;
            if !validity_values.get_bit_unchecked(idx) {
                unset_bit_raw(validity_ptr, i);
            }
        });
    };
    let arr = PrimitiveArray::new(T::PRIMITIVE.into(), values.into(), Some(validity.into()));

    Box::new(arr)
}