lpvo_do_read
rv = lpvo_do_read(dev, buf, count);
static ssize_t lpvo_do_read(struct lpvo *, char *, size_t);
nchar = lpvo_do_read(GPIB_DEV, buffer, 64);
b->nchar = lpvo_do_read(GPIB_DEV, b->inbuf, INBUF_SIZE);
retval = lpvo_do_read(GPIB_DEV, inbuf, 1);
retval += lpvo_do_read(GPIB_DEV, inbuf + 1, 1);