Function handle_mutable_buffer_remainder 

fn handle_mutable_buffer_remainder<F>(
    op: &mut F,
    start_remainder_mut_slice: &mut [u8],
    right_remainder_bits: u64,
    remainder_len: usize,
)
where
    F: FnMut(u64, u64) -> u64,

Handle remainder bits (< 64 bits) for binary operations.

This function processes the bits that don’t form a complete u64 chunk, ensuring that bits outside the operation range are preserved.

Arguments

• op - Binary operation to apply
• start_remainder_mut_slice - slice to the start of remainder bytes the length must be equal to ceil(remainder_len, 8)
• right_remainder_bits - Right operand bits
• remainder_len - Number of remainder bits