Function maskblit 

pub unsafe extern "C" fn maskblit(
    x: c_int,
    y: c_int,
    source: *mut c_uchar,
    width: c_int,
    height: c_int,
    srcx: c_int,
    srcy: c_int,
    srcw: c_int,
    srch: c_int,
    colorkey: c_int,
)