Function encoding_mem_copy_basic_latin_to_ascii 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn encoding_mem_copy_basic_latin_to_ascii(
    src: *const u16,
    src_len: usize,
    dst: *mut u8,
    dst_len: usize,
) -> usize

Copies Basic Latin from source to destination narrowing it to ASCII up to the first non-Basic Latin code unit (or the end of the input if it is Basic Latin in its entirety).

The length of the destination buffer must be at least the length of the source buffer.

Returns the number of bytes written.

Panics

Panics if the destination buffer is shorter than stated above.

Undefined behavior

UB ensues if src and src_len don’t designate a valid memory block, if src is NULL, if dst and dst_len don’t designate a valid memory block, if dst is NULL or if the two memory blocks overlap. (If src_len is 0, src may be bogus but still has to be non-NULL and aligned. Likewise for dst and dst_len.)