Function reject_static_unless_read 

pub fn reject_static_unless_read(
    is_static: bool,
    data: &[u8],
    gas_limit: u64,
    reads: &[[u8; 4]],
) -> Option<PrecompileResult>

Like reject_static_write but for a mostly-writing precompile: under read-only, reject every method except the listed read-only (view/pure) selectors.