/* transport.h - MTP/audio transport * Author: Anders Baekgaard <ab@dicea.dk> * This work is included with chan_ss7, see copyright below. *//* * This file is part of chan_ss7. * * chan_ss7 is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * chan_ss7 is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with chan_ss7; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA *//* We read audio in chunks of 160 bytes = 20 msec. */#define AUDIO_READSIZE 160/* We run the signalling link in clear channel mode, since we have seen   unreliable behaviour with the zaptel HDLC/FCS code, and since it gives   more control of buffering and better diagnostics (raw bit dumps ...).   Use 4 buffers of 16 bytes each; that amounts to around 8 msecs of   latency of write and of read slack before packet loss. An 8 byte buffer   size is the minimum allowed, giving maximum responsiveness.*/enum {  NUM_ZAP_BUF = 4,#ifdef MTP_OVER_UDP  ZAP_BUF_SIZE = 64,#else  ZAP_BUF_SIZE = 16,#endif};int openchannel(struct link* link, int channel);void flushchannel(int fd, int cic);int adjust_buffers(int fd, int cic);int openschannel(struct link* link);int io_get_zaptel_event(int fd, int* e);int io_enable_echo_cancellation(int fd, int cic, int echocan_taps, int echocan_train);void io_disable_echo_cancellation(int fd, int cic);int io_send_dtmf(int fd, int cic, char digit);