Function encoding_mem_is_basic_latin 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn encoding_mem_is_basic_latin(
    buffer: *const u16,
    len: usize,
) -> bool

Checks whether the buffer is all-Basic Latin (i.e. UTF-16 representing only ASCII characters).

May read the entire buffer even if it isn’t all-ASCII. (I.e. the function is not guaranteed to fail fast.)

Undefined behavior

UB ensues if buffer and buffer_len don’t designate a valid memory block or if buffer is NULL. (If buffer_len is 0, buffer may be bogus but still has to be non-NULL and aligned.)