findCie

fn findCie(unwind: *const Unwind, offset: u64) ?*const CommonInformationEntry {
    const offsets = unwind.cie_list.items(.offset);
    if (offsets.len == 0) return null;
    var start: usize = 0;
    var len: usize = offsets.len;
    while (len > 1) {
        const mid = len / 2;
        if (offset < offsets[start + mid]) {
            len = mid;
        } else {
            start += mid;
            len -= mid;
        }
    }
    if (offsets[start] != offset) return null;
    return &unwind.cie_list.items(.cie)[start];
}