VBI_BUFFER_SIZE
if (readsize >= VBI_BUFFER_SIZE - bktr->vbistart) {
readsize2 = VBI_BUFFER_SIZE - bktr->vbistart;
bktr->vbistart = bktr->vbistart % VBI_BUFFER_SIZE; /* wrap around if needed */
VBI_BUFFER_SIZE);
if (bktr->vbisize + VBI_DATA_SIZE > VBI_BUFFER_SIZE) return;
bktr->vbiinsert = (bktr->vbiinsert % VBI_BUFFER_SIZE);
bzero((caddr_t) bktr->vbibuffer, VBI_BUFFER_SIZE);