MAX_D_FRAMES
struct zt za[MAX_D_FRAMES + 1];
df->f2 = ((df->f2 + 1) & MAX_D_FRAMES) |
(MAX_D_FRAMES + 1); /* next buffer */
df->f2 = ((df->f2 + 1) & MAX_D_FRAMES) |
(MAX_D_FRAMES + 1); /* next buffer */
fcnt += (MAX_D_FRAMES + 1); /* if wrap around */
if (fcnt > (MAX_D_FRAMES - 1)) {