sndbuf_acquire
sndbuf_acquire(to, to->tmpbuf, cnt);
int sndbuf_acquire(struct snd_dbuf *b, u_int8_t *from, unsigned int count);
sndbuf_acquire(b, NULL, amt);
sndbuf_acquire(bs, NULL, sndbuf_getfree(bs));
sndbuf_acquire(bs, NULL, sz);
sndbuf_acquire(bs, NULL, threshold);
sndbuf_acquire(bs, NULL, threshold);
sndbuf_acquire(bs, bs->shadbuf, bs->sl);
sndbuf_acquire(b, b->tmpbuf, cnt);
sndbuf_acquire(bs, bs->tmpbuf, cnt);
sndbuf_acquire(ch->bufsoft, NULL,