Function libeyelink_sys::eyelink_get_file_block

pub unsafe extern "C" fn eyelink_get_file_block(
    buf: *mut c_void, 
    offset: *mut INT32
) -> INT16

@ingroup datafile Get next block of file. If \c <offset> is not \c NULL, will be filled with block-start offset in file.

@return negative if error, \c NO_REPLY if waiting for packet, else block size (0..512). size is < 512 (can be 0) if at EOF.

@remark Internal function. use receive_data_file()