/* $Id$
 *
 * Audio crossconnecting/conferrencing (hardware level).
 *
 * Copyright 2002 by Andreas Eversberg (jolly@eversberg.eu)
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 */

/*
 * The process of adding and removing parties to/from a conference:
 *
 * There is a chain of conference_t which has one or more members in a chain
 * of conf_member_t.
 *
 * After a party is added, the conference is checked for hardware capability.
 * Also if a party is removed, the conference is checked again.
 *
 * There are 3 different solutions: -1 = software, 0 = hardware-crossconnect
 * 1-n = hardware-conference. The n will give the conference number.
 *
 * Depending on the change after removal or insertion of a party, hardware
 * commands are given.
 *
 * The current solution is stored within the conference_t entry.
 */

/* HOW THE CMX WORKS:
 *
 * There are 3 types of interaction: One member is alone, in this case only
 * data flow from upper to lower layer is done.
 * Two members will also exchange their data so they are crossconnected.
 * Three or more members will be added in a conference and will hear each
 * other but will not receive their own speech (echo) if not enabled.
 *
 * Features of CMX are:
 *  - Crossconnecting or even conference, if more than two members are together.
 *  - Force mixing of transmit data with other crossconnect/conference members.
 *  - Echo generation to benchmark the delay of audio processing.
 *  - Use hardware to minimize cpu load, disable FIFO load and minimize delay.
 *  - Dejittering and clock generation.
 *
 * There are 2 buffers:
 *
 *
 * RX-Buffer
 *                 R             W
 *                 |             |
 * ----------------+-------------+-------------------
 * 
 * The rx-buffer is a ring buffer used to store the received data for each
 * individual member. This is only the case if data needs to be dejittered
 * or in case of a conference where different clocks require reclocking.
 * The transmit-clock (R) will read the buffer.
 * If the clock overruns the write-pointer, we will have a buffer underrun.
 * If the write pointer always has a certain distance from the transmit-
 * clock, we will have a delay. The delay will dynamically be increased and
 * reduced.
 *
 *
 * TX-Buffer
 *                  R        W
 *                  |        |
 * -----------------+--------+-----------------------
 *
 * The tx-buffer is a ring buffer to queue the transmit data from user space
 * until it will be mixed or sent. There are two pointers, R and W. If the write
 * pointer W would reach or overrun R, the buffer would overrun. In this case
 * (some) data is dropped so that it will not overrun.
 *
 *
 * Clock:
 * 
 * A Clock is not required, if the data source has exactly one clock. In this
 * case the data source is forwarded to the destination.
 *
 * A Clock is required, because the data source
 *  - has multiple clocks.
 *  - has no clock due to jitter (VoIP).
 * In this case the system's clock is used. The clock resolution depends on
 * the jiffie resolution.
 *
 * If a member joins a conference:
 *
 * - If a member joins, its rx_buff is set to silence and change read pointer
 *   to transmit clock.
 *
 * The procedure of received data from card is explained in cmx_receive.
 * The procedure of received data from user space is explained in cmx_transmit.
 * The procedure of transmit data to card is cmx_send.
 *
 *
 * Interaction with other features:
 *
 * DTMF:
 * DTMF decoding is done before the data is crossconnected.
 *
 * Volume change:
 * Changing rx-volume is done before the data is crossconnected. The tx-volume
 * must be changed whenever data is transmitted to the card by the cmx.
 *
 * Tones:
 * If a tone is enabled, it will be processed whenever data is transmitted to
 * the card. It will replace the tx-data from the user space.
 * If tones are generated by hardware, this conference member is removed for
 * this time.
 *
 * Disable rx-data:
 * If cmx is realized in hardware, rx data will be disabled if requested by
 * the upper layer. If dtmf decoding is done by software and enabled, rx data
 * will not be diabled but blocked to the upper layer.
 *
 * HFC conference engine:
 * If it is possible to realize all features using hardware, hardware will be
 * used if not forbidden by control command. Disabling rx-data provides
 * absolutely traffic free audio processing. (except for the quick 1-frame
 * upload of a tone loop, only once for a new tone)
 *
 */

// delay.h is required for hw_lock.h
#include <linux/delay.h>
#include <linux/vmalloc.h>
#include "layer1.h"
#include "helper.h"
#include "debug.h"
#include "dsp.h"

//#define CMX_CONF_DEBUG /* debugging of multi party conference, by using conference even with two members */
//#define CMX_DEBUG /* massive read/write pointer output */

LIST_HEAD(Conf_list);

/*
 * debug cmx memory structure
 */
void
dsp_cmx_debug(dsp_t *dsp)
{
	conference_t	*conf;
	conf_member_t	*member;
	dsp_t		*odsp;

	printk(KERN_DEBUG "-----Current DSP\n");
	list_for_each_entry(odsp, &dsp_obj.ilist, list) {
		printk(KERN_DEBUG "* %s echo=%d txmix=%d", odsp->inst.name, odsp->echo, odsp->tx_mix);
		if (odsp->conf)
			printk(" (Conf %d)", odsp->conf->id);
		if (dsp == odsp)
			printk(" *this*");
		printk("\n");
	}
	printk(KERN_DEBUG "-----Current Conf:\n");
	list_for_each_entry(conf, &Conf_list, list) {
		printk(KERN_DEBUG "* Conf %d (%p)\n", conf->id, conf);
		list_for_each_entry(member, &conf->mlist, list) {
			printk(KERN_DEBUG
				"  - member = %s (slot_tx %d, bank_tx %d, slot_rx %d, bank_rx %d hfc_conf %d)%s\n",
				member->dsp->inst.name, member->dsp->pcm_slot_tx, member->dsp->pcm_bank_tx,
				member->dsp->pcm_slot_rx, member->dsp->pcm_bank_rx, member->dsp->hfc_conf,
				(member->dsp==dsp)?" *this*":"");
		}
	}
	printk(KERN_DEBUG "-----end\n");
}

/*
 * search conference
 */
static conference_t 
*dsp_cmx_search_conf(u32 id)
{
	conference_t *conf;

	if (!id) {
		printk(KERN_WARNING "%s: conference ID is 0.\n", 
			__FUNCTION__);
		return(NULL);
	}

	/* search conference */
	list_for_each_entry(conf, &Conf_list, list)
		if (conf->id == id)
			return(conf);

	return(NULL);
}


/*
 * add member to conference
 */
static int
dsp_cmx_add_conf_member(dsp_t *dsp, conference_t *conf)
{
	conf_member_t *member;

	if (!conf || !dsp) {
		printk(KERN_WARNING "%s: conf or dsp is 0.\n", __FUNCTION__);
		return(-EINVAL);
	}
	if (dsp->member) {
		printk(KERN_WARNING "%s: dsp is already member in a conf.\n", 
			__FUNCTION__);
		return(-EINVAL);
	}

	if (dsp->conf) {
		printk(KERN_WARNING "%s: dsp is already in a conf.\n", 
			__FUNCTION__);
		return(-EINVAL);
	}

	if (!(member = kmalloc(sizeof(conf_member_t), GFP_ATOMIC))) {
		printk(KERN_ERR "kmalloc conf_member_t failed\n");
		return(-ENOMEM);
	}
	memset(member, 0, sizeof(conf_member_t));
	member->dsp = dsp;
	/* clear rx buffer */
	memset(dsp->rx_buff, dsp_silence, sizeof(dsp->rx_buff));
	dsp->rx_W = dsp->rx_R = -1; /* reset pointers */

	list_add_tail(&member->list, &conf->mlist);

	dsp->conf = conf;
	dsp->member = member;

	return(0);
}


/*
 * del member from conference
 */
int
dsp_cmx_del_conf_member(dsp_t *dsp)
{
	conf_member_t *member;

	if (!dsp) {
		printk(KERN_WARNING "%s: dsp is 0.\n", 
			__FUNCTION__);
		return(-EINVAL);
	}

	if (!dsp->conf) {
		printk(KERN_WARNING "%s: dsp is not in a conf.\n", 
			__FUNCTION__);
		return(-EINVAL);
	}

	if (list_empty(&dsp->conf->mlist)) {
		printk(KERN_WARNING "%s: dsp has linked an empty conf.\n", 
			__FUNCTION__);
		return(-EINVAL);
	}

	/* find us in conf */
	list_for_each_entry(member, &dsp->conf->mlist, list) {
		if (member->dsp == dsp) {
			list_del(&member->list);
			dsp->conf = NULL;
			dsp->member = NULL;
			kfree(member);
			return(0);
		}
	}
	printk(KERN_WARNING "%s: dsp is not present in its own conf_meber list.\n", 
		__FUNCTION__);

	return(-EINVAL);
}


/*
 * new conference
 */
static conference_t
*dsp_cmx_new_conf(u32 id)
{
	conference_t *conf;

	if (!id) {
		printk(KERN_WARNING "%s: id is 0.\n", 
			__FUNCTION__);
		return(NULL);
	}

	if (!(conf = kmalloc(sizeof(conference_t), GFP_ATOMIC))) {
		printk(KERN_ERR "kmalloc conference_t failed\n");
		return(NULL);
	}
	memset(conf, 0, sizeof(conference_t));
	INIT_LIST_HEAD(&conf->mlist);
	conf->id = id;

	list_add_tail(&conf->list, &Conf_list);

	return(conf);
}


/*
 * del conference
 */
int
dsp_cmx_del_conf(conference_t *conf)
{
	if (!conf) {
		printk(KERN_WARNING "%s: conf is null.\n", 
			__FUNCTION__);
		return(-EINVAL);
	}

	if (!list_empty(&conf->mlist)) {
		printk(KERN_WARNING "%s: conf not empty.\n", 
			__FUNCTION__);
		return(-EINVAL);
	}
	list_del(&conf->list);
	kfree(conf);

	return(0);
}


/*
 * send HW message to hfc card
 */
static void
dsp_cmx_hw_message(dsp_t *dsp, u32 message, u32 param1, u32 param2, u32 param3, u32 param4)
{
	struct sk_buff *nskb;
	u32 param[4];

	param[0] = param1;
	param[1] = param2;
	param[2] = param3;
	param[3] = param4;
	nskb = create_link_skb(PH_CONTROL | REQUEST, message, sizeof(param), param, 0);
	if (!nskb) {
		printk(KERN_ERR "%s: No mem for skb.\n", __FUNCTION__);
		return;
	}
	/* unlocking is not required, because we don't expect a response */
	if (mISDN_queue_down(&dsp->inst, 0, nskb))
		dev_kfree_skb(nskb);
}


/*
 * do hardware update and set the software/hardware flag
 *
 * either a conference or a dsp instance can be given
 * if only dsp instance is given, the instance is not associated with a conf
 * and therefore removed. if a conference is given, the dsp is expected to
 * be member of that conference.
 */
void 
dsp_cmx_hardware(conference_t *conf, dsp_t *dsp)
{
	conf_member_t	*member, *nextm;
	dsp_t		*finddsp;
	int		memb = 0, i, ii, i1, i2;
	int		freeunits[8];
	u_char		freeslots[256];
	int		same_hfc = -1, same_pcm = -1, current_conf = -1, all_conf = 1;

	/* dsp gets updated (no conf) */
//printk("-----1\n");
	if (!conf) {
//printk("-----2\n");
		if (!dsp)
			return;
//printk("-----3\n");
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "%s checking dsp %s\n", __FUNCTION__, dsp->inst.name);
//printk("-----a\n");
		one_member:
		/* remove HFC conference if enabled */
		if (dsp->hfc_conf >= 0) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s removing %s from HFC conf %d because dsp is split\n", __FUNCTION__, dsp->inst.name, dsp->hfc_conf);
			dsp_cmx_hw_message(dsp, HW_CONF_SPLIT, 0, 0, 0, 0);
			dsp->hfc_conf = -1;
		}
		if (!dsp->echo) {
			/* NO ECHO: remove PCM slot if assigned */
			if (dsp->pcm_slot_tx>=0 || dsp->pcm_slot_rx>=0) {
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s removing %s from PCM slot %d (TX) %d (RX) because dsp is split (no echo)\n", __FUNCTION__, dsp->inst.name, dsp->pcm_slot_tx, dsp->pcm_slot_rx);
				dsp_cmx_hw_message(dsp, HW_PCM_DISC, 0, 0, 0, 0);
				dsp->pcm_slot_tx = -1;
				dsp->pcm_bank_tx = -1;
				dsp->pcm_slot_rx = -1;
				dsp->pcm_bank_rx = -1;
			}
			return;
		}
		/* ECHO: already echo */
		if (dsp->pcm_slot_tx>=0 && dsp->pcm_slot_rx<0
		 && dsp->pcm_bank_tx==2 && dsp->pcm_bank_rx==2)
			return;
		/* ECHO: if slot already assigned */
		if (dsp->pcm_slot_tx>=0) {
			dsp->pcm_slot_rx = dsp->pcm_slot_tx;
			dsp->pcm_bank_tx = 2; /* loop */
			dsp->pcm_bank_rx = 2;
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s refresh %s for echo using slot %d\n", __FUNCTION__, dsp->inst.name, dsp->pcm_slot_tx);
			dsp_cmx_hw_message(dsp, HW_PCM_CONN, dsp->pcm_slot_tx, 2, dsp->pcm_slot_rx, 2);
			return;
		}
		/* ECHO: find slot */
		dsp->pcm_slot_tx = -1;
		dsp->pcm_slot_rx = -1;
		memset(freeslots, 1, sizeof(freeslots));
		list_for_each_entry(finddsp, &dsp_obj.ilist, list) {
			 if (finddsp->features.pcm_id==dsp->features.pcm_id) {
				if (finddsp->pcm_slot_rx>=0
				 && finddsp->pcm_slot_rx<sizeof(freeslots))
					freeslots[finddsp->pcm_slot_tx] = 0;
				if (finddsp->pcm_slot_tx>=0
				 && finddsp->pcm_slot_tx<sizeof(freeslots))
					freeslots[finddsp->pcm_slot_rx] = 0;
			}
		}
		i = 0;
		ii = dsp->features.pcm_slots;
		while(i < ii) {
			if (freeslots[i])
				break;
			i++;
		}
		if (i == ii) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s no slot available for echo\n", __FUNCTION__);
			/* no more slots available */
			return;
		}
		/* assign free slot */
		dsp->pcm_slot_tx = i;
		dsp->pcm_slot_rx = i;
		dsp->pcm_bank_tx = 2; /* loop */
		dsp->pcm_bank_rx = 2;
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "%s assign echo for %s using slot %d\n", __FUNCTION__, dsp->inst.name, dsp->pcm_slot_tx);
		dsp_cmx_hw_message(dsp, HW_PCM_CONN, dsp->pcm_slot_tx, 2, dsp->pcm_slot_rx, 2);
		return;
	}

//printk("-----4\n");
	/* conf gets updated (all members) */
	if (dsp_debug & DEBUG_DSP_CMX)
		printk(KERN_DEBUG "%s checking conference %d\n", __FUNCTION__, conf->id);
//printk("-----5\n");
	
	if (list_empty(&conf->mlist)) {
		printk(KERN_ERR "%s: conference whithout members\n", __FUNCTION__);
		return;
	}
	member = list_entry(conf->mlist.next, conf_member_t, list);
	same_hfc = member->dsp->features.hfc_id;
	same_pcm = member->dsp->features.pcm_id;
	/* check all members in our conference */
	list_for_each_entry(member, &conf->mlist, list) {
		/* check if member uses mixing */
		if (member->dsp->tx_mix) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because tx_mix is turned on\n", __FUNCTION__, member->dsp->inst.name);
			conf_software:
//			printk(KERN_NOTICE "****** SOFTWARE CONFERENCE\n");
			list_for_each_entry(member, &conf->mlist, list) {
				dsp = member->dsp;
				/* remove HFC conference if enabled */
				if (dsp->hfc_conf >= 0) {
					if (dsp_debug & DEBUG_DSP_CMX)
						printk(KERN_DEBUG "%s removing %s from HFC conf %d because not possible with hardware\n", __FUNCTION__, dsp->inst.name, dsp->hfc_conf);
					dsp_cmx_hw_message(dsp, HW_CONF_SPLIT, 0, 0, 0, 0);
					dsp->hfc_conf = -1;
				}
				/* remove PCM slot if assigned */
				if (dsp->pcm_slot_tx>=0 || dsp->pcm_slot_rx>=0) {
					if (dsp_debug & DEBUG_DSP_CMX)
						printk(KERN_DEBUG "%s removing %s from PCM slot %d (TX) slot %d (RX) because not possible with hardware\n", __FUNCTION__, dsp->inst.name, dsp->pcm_slot_tx, dsp->pcm_slot_rx);
					dsp_cmx_hw_message(dsp, HW_PCM_DISC, 0, 0, 0, 0);
					dsp->pcm_slot_tx = -1;
					dsp->pcm_bank_tx = -1;
					dsp->pcm_slot_rx = -1;
					dsp->pcm_bank_rx = -1;
				}
			}
			conf->hardware = 0;
			conf->software = 1;
			return;
		}
		/* check if member has echo turned on */
		if (member->dsp->echo) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because echo is turned on\n", __FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		/* check if member has tx_mix turned on */
		if (member->dsp->tx_mix) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because tx_mix is turned on\n", __FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		/* check if member changes volume at an not suppoted level */
		if (member->dsp->tx_volume) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because tx_volume is changed\n", __FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		if (member->dsp->rx_volume) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because rx_volume is changed\n", __FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		/* check if encryption is enabled */
		if (member->dsp->bf_enable) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because encryption is enabled\n", __FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		/* check if echo cancellation is enabled */
		if (member->dsp->cancel_enable) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because echo cancellation is enabled\n", __FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		/* check if member is on a card with PCM support */
		if (member->dsp->features.pcm_id < 0) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because dsp has no PCM bus\n", __FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		/* check if relations are on the same PCM bus */
		if (member->dsp->features.pcm_id != same_pcm) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s dsp %s cannot form a conf, because dsp is on a different PCM bus than the first dsp\n",
					__FUNCTION__, member->dsp->inst.name);
			goto conf_software;
		}
		/* determine if members are on the same hfc chip */
		if (same_hfc != member->dsp->features.hfc_id)
			same_hfc = -1;
		/* if there are members already in a conference */
		if (current_conf<0 && member->dsp->hfc_conf>=0)
			current_conf = member->dsp->hfc_conf;
		/* if any member is not in a conference */
		if (member->dsp->hfc_conf < 0)
			all_conf = 0;

		memb++;
	}

	/* if no member, this is an error */
	if (memb < 1)
		return;

	/* one member */
	if (memb == 1) {
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "%s conf %d cannot form a HW conference, because dsp is alone\n", __FUNCTION__, conf->id);
		conf->hardware = 0;
		conf->software = 1;
		member = list_entry(conf->mlist.next, conf_member_t, list);
		dsp = member->dsp;
		goto one_member;
	}

	/* ok, now we are sure that all members are on the same pcm.
	 * now we will see if we have only two members, so we can do
	 * crossconnections, which don't have any limitations.
	 */

	/* if we have only two members */
	if (memb == 2) {
		member = list_entry(conf->mlist.next, conf_member_t, list);
		nextm = list_entry(member->list.next, conf_member_t, list);
		/* remove HFC conference if enabled */
		if (member->dsp->hfc_conf >= 0) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s removing %s from HFC conf %d because two parties require only a PCM slot\n", __FUNCTION__, member->dsp->inst.name, member->dsp->hfc_conf);
			dsp_cmx_hw_message(member->dsp, HW_CONF_SPLIT, 0, 0, 0, 0);
			member->dsp->hfc_conf = -1;
		}
		if (nextm->dsp->hfc_conf >= 0) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s removing %s from HFC conf %d because two parties require only a PCM slot\n", __FUNCTION__, nextm->dsp->inst.name, nextm->dsp->hfc_conf);
			dsp_cmx_hw_message(nextm->dsp, HW_CONF_SPLIT, 0, 0, 0, 0);
			nextm->dsp->hfc_conf = -1;
		}
		/* if members have two banks (and not on the same chip) */
		if (member->dsp->features.pcm_banks>1
		 && nextm->dsp->features.pcm_banks>1
		 && member->dsp->features.hfc_id!=nextm->dsp->features.hfc_id) {
			/* if both members have same slots with crossed banks */
			if (member->dsp->pcm_slot_tx>=0
			 && member->dsp->pcm_slot_rx>=0
			 && nextm->dsp->pcm_slot_tx>=0
			 && nextm->dsp->pcm_slot_rx>=0
			 && nextm->dsp->pcm_slot_tx==member->dsp->pcm_slot_rx
			 && nextm->dsp->pcm_slot_rx==member->dsp->pcm_slot_tx
			 && nextm->dsp->pcm_slot_tx==member->dsp->pcm_slot_tx
			 && member->dsp->pcm_bank_tx!=member->dsp->pcm_bank_rx
			 && nextm->dsp->pcm_bank_tx!=nextm->dsp->pcm_bank_rx) {
				/* all members have same slot */
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s dsp %s & %s stay joined on PCM slot %d bank %d (TX) bank %d (RX) (on different chips)\n", __FUNCTION__,
						member->dsp->inst.name, nextm->dsp->inst.name,
						member->dsp->pcm_slot_tx, member->dsp->pcm_bank_tx, member->dsp->pcm_bank_rx);
				conf->hardware = 0;
				conf->software = 1;
				return;
			}
			/* find a new slot */
			memset(freeslots, 1, sizeof(freeslots));
			list_for_each_entry(dsp, &dsp_obj.ilist, list) {
				if (dsp!=member->dsp
				 && dsp!=nextm->dsp
				 && member->dsp->features.pcm_id==dsp->features.pcm_id) {
					if (dsp->pcm_slot_rx>=0
					 && dsp->pcm_slot_rx<sizeof(freeslots))
						freeslots[dsp->pcm_slot_tx] = 0;
					if (dsp->pcm_slot_tx>=0
					 && dsp->pcm_slot_tx<sizeof(freeslots))
						freeslots[dsp->pcm_slot_rx] = 0;
				}
			}
			i = 0;
			ii = member->dsp->features.pcm_slots;
			while(i < ii) {
				if (freeslots[i])
					break;
				i++;
			}
			if (i == ii) {
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s no slot available for %s & %s\n", __FUNCTION__,
						member->dsp->inst.name, nextm->dsp->inst.name);
				/* no more slots available */
				goto conf_software;
			}
			/* assign free slot */
			member->dsp->pcm_slot_tx = i;
			member->dsp->pcm_slot_rx = i;
			nextm->dsp->pcm_slot_tx = i;
			nextm->dsp->pcm_slot_rx = i;
			member->dsp->pcm_bank_rx = 0;
			member->dsp->pcm_bank_tx = 1;
			nextm->dsp->pcm_bank_rx = 1;
			nextm->dsp->pcm_bank_tx = 0;
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s adding %s & %s to new PCM slot %d (TX and RX on different chips) because both members have not same slots\n", __FUNCTION__,
					member->dsp->inst.name, nextm->dsp->inst.name, member->dsp->pcm_slot_tx);
			dsp_cmx_hw_message(member->dsp, HW_PCM_CONN, member->dsp->pcm_slot_tx, member->dsp->pcm_bank_tx,
				member->dsp->pcm_slot_rx, member->dsp->pcm_bank_rx);
			dsp_cmx_hw_message(nextm->dsp, HW_PCM_CONN, nextm->dsp->pcm_slot_tx, nextm->dsp->pcm_bank_tx,
				nextm->dsp->pcm_slot_rx, nextm->dsp->pcm_bank_rx);
			conf->hardware = 1;
			conf->software = 0;
			return;
		/* if members have one bank (or on the same chip) */
		} else {
			/* if both members have different crossed slots */
			if (member->dsp->pcm_slot_tx>=0
			 && member->dsp->pcm_slot_rx>=0
			 && nextm->dsp->pcm_slot_tx>=0
			 && nextm->dsp->pcm_slot_rx>=0
			 && nextm->dsp->pcm_slot_tx==member->dsp->pcm_slot_rx
			 && nextm->dsp->pcm_slot_rx==member->dsp->pcm_slot_tx
			 && member->dsp->pcm_slot_tx!=member->dsp->pcm_slot_rx
			 && member->dsp->pcm_bank_tx==0
			 && member->dsp->pcm_bank_rx==0
			 && nextm->dsp->pcm_bank_tx==0
			 && nextm->dsp->pcm_bank_rx==0) {
				/* all members have same slot */
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s dsp %s & %s stay joined on PCM slot %d (TX) %d (RX) on same chip or one bank PCM)\n", __FUNCTION__,
						member->dsp->inst.name, nextm->dsp->inst.name, member->dsp->pcm_slot_tx, member->dsp->pcm_slot_rx);
				conf->hardware = 0;
				conf->software = 1;
				return;
			}
			/* find two new slot */
			memset(freeslots, 1, sizeof(freeslots));
			list_for_each_entry(dsp, &dsp_obj.ilist, list) {
				if (dsp!=member->dsp
				 && dsp!=nextm->dsp
				 && member->dsp->features.pcm_id==dsp->features.pcm_id) {
					if (dsp->pcm_slot_rx>=0
					 && dsp->pcm_slot_rx<sizeof(freeslots))
						freeslots[dsp->pcm_slot_tx] = 0;
					if (dsp->pcm_slot_tx>=0
					 && dsp->pcm_slot_tx<sizeof(freeslots))
						freeslots[dsp->pcm_slot_rx] = 0;
				}
			}
			i1 = 0;
			ii = member->dsp->features.pcm_slots;
			while(i1 < ii) {
				if (freeslots[i1])
					break;
				i1++;
			}
			if (i1 == ii) {
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s no slot available for %s & %s\n", __FUNCTION__,
						member->dsp->inst.name, nextm->dsp->inst.name);
				/* no more slots available */
				goto conf_software;
			}
			i2 = i1+1;
			while(i2 < ii) {
				if (freeslots[i2])
					break;
				i2++;
			}
			if (i2 == ii) {
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s no slot available for %s & %s\n", __FUNCTION__,
						member->dsp->inst.name, nextm->dsp->inst.name);
				/* no more slots available */
				goto conf_software;
			}
			/* assign free slots */
			member->dsp->pcm_slot_tx = i1;
			member->dsp->pcm_slot_rx = i2;
			nextm->dsp->pcm_slot_tx = i2;
			nextm->dsp->pcm_slot_rx = i1;
			member->dsp->pcm_bank_rx = 0;
			member->dsp->pcm_bank_tx = 0;
			nextm->dsp->pcm_bank_rx = 0;
			nextm->dsp->pcm_bank_tx = 0;
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s adding %s & %s to new PCM slot %d (TX) %d (RX) on same chip or one bank PCM, because both members have not crossed slots\n", __FUNCTION__,
					member->dsp->inst.name, nextm->dsp->inst.name, member->dsp->pcm_slot_tx,
					member->dsp->pcm_slot_rx);
			dsp_cmx_hw_message(member->dsp, HW_PCM_CONN, member->dsp->pcm_slot_tx, member->dsp->pcm_bank_tx, member->dsp->pcm_slot_rx, member->dsp->pcm_bank_rx);
			dsp_cmx_hw_message(nextm->dsp, HW_PCM_CONN, nextm->dsp->pcm_slot_tx, nextm->dsp->pcm_bank_tx, nextm->dsp->pcm_slot_rx, nextm->dsp->pcm_bank_rx);
			conf->hardware = 1;
			conf->software = 0;
			return;
		}
	}

	/* if we have more than two, we may check if we have a conference
	 * unit available on the chip. also all members must be on the same
	 */

	/* if not the same HFC chip */
	if (same_hfc < 0) {
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "%s conference %d cannot be formed, because members are on different chips or not on HFC chip\n",
				__FUNCTION__, conf->id);
		goto conf_software;
	}

	/* if all members already have the same conference */
	if (all_conf)
		return;

	/* if there is an existing conference, but not all members have joined
	 */
	if (current_conf >= 0) {
		join_members:
		list_for_each_entry(member, &conf->mlist, list) {
			/* join to current conference */
			if (member->dsp->hfc_conf == current_conf) {
				continue;
			}
			/* get a free timeslot first */
			memset(freeslots, 1, sizeof(freeslots));
			list_for_each_entry(dsp, &dsp_obj.ilist, list) {
				/* not checking current member, because
				 * slot will be overwritten.
				 */
				if (dsp!=member->dsp
				/* dsp must be on the same PCM */
				 && member->dsp->features.pcm_id==dsp->features.pcm_id) {
					/* dsp must be on a slot */
					if (dsp->pcm_slot_tx>=0
					 && dsp->pcm_slot_tx<sizeof(freeslots))
						freeslots[dsp->pcm_slot_tx] = 0;
					if (dsp->pcm_slot_rx>=0
					 && dsp->pcm_slot_rx<sizeof(freeslots))
						freeslots[dsp->pcm_slot_rx] = 0;
				}
			}
			i = 0;
			ii = member->dsp->features.pcm_slots;
			while(i < ii) {
				if (freeslots[i])
					break;
				i++;
			}
			if (i == ii) {
				/* no more slots available */
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s conference %d cannot be formed, because no slot free\n", __FUNCTION__, conf->id);
				goto conf_software;
			}
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "%s changing dsp %s to HW conference %d slot %d\n", __FUNCTION__, member->dsp->inst.name, current_conf, i);
			/* assign free slot & set PCM & join conf */
			member->dsp->pcm_slot_tx = i;
			member->dsp->pcm_slot_rx = i;
			member->dsp->pcm_bank_tx = 2; /* loop */
			member->dsp->pcm_bank_rx = 2;
			member->dsp->hfc_conf = current_conf;
			dsp_cmx_hw_message(member->dsp, HW_PCM_CONN, i, 2, i, 2);
			dsp_cmx_hw_message(member->dsp, HW_CONF_JOIN, current_conf, 0, 0, 0);
		}
		return;
	}

	/* no member is in a conference yet, so we find a free one
	 */
	memset(freeunits, 1, sizeof(freeunits));
	list_for_each_entry(dsp, &dsp_obj.ilist, list) {
		/* dsp must be on the same chip */
		if (dsp->features.hfc_id==same_hfc
		/* dsp must have joined a HW conference */
		 && dsp->hfc_conf>=0
		/* slot must be within range */
		 && dsp->hfc_conf<8)
			freeunits[dsp->hfc_conf] = 0;
	}
	i = 0;
	ii = 8;
	while(i < ii) {
		if (freeunits[i])
			break;
		i++;
	}
	if (i == ii) {
		/* no more conferences available */
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "%s conference %d cannot be formed, because no conference number free\n", __FUNCTION__, conf->id);
		goto conf_software;
	}
	/* join all members */
	current_conf = i;
	goto join_members;
}


/*
 * conf_id != 0: join or change conference
 * conf_id == 0: split from conference if not already
 */
int
dsp_cmx_conf(dsp_t *dsp, u32 conf_id)
{
	int err;
	conference_t *conf;

	/* if conference doesn't change */
	if (dsp->conf_id == conf_id)
		return(0);

	spin_lock(&dsp->feature_lock);
	if (dsp->feature_state != FEAT_STATE_RECEIVED) {
		dsp->queue_conf_id=conf_id;	
		spin_unlock(&dsp->feature_lock);
		return 0;
	}
	spin_unlock(&dsp->feature_lock);

	/* first remove us from current conf */
	if (dsp->conf_id) {
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "removing us from conference %d\n",
				dsp->conf->id);
		/* remove us from conf */
		conf = dsp->conf;
		err = dsp_cmx_del_conf_member(dsp);
		if (err)
			return(err);
		dsp->conf_id = 0;

		/* update hardware */
		dsp_cmx_hardware(NULL, dsp);

		/* conf now empty? */
		if (list_empty(&conf->mlist)) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "conference is empty, so we remove it.\n");
			err = dsp_cmx_del_conf(conf);
			if (err)
				return(err);
		} else {
			/* update members left on conf */
			dsp_cmx_hardware(conf, NULL);
		}
	}

	/* if split */
	if (!conf_id)
		return(0);

	/* now add us to conf */
	if (dsp_debug & DEBUG_DSP_CMX)
		printk(KERN_DEBUG "searching conference %d\n",
			conf_id);
	conf = dsp_cmx_search_conf(conf_id);
	if (!conf) {
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "conference doesn't exist yet, creating.\n");
		/* the conference doesn't exist, so we create */
		conf = dsp_cmx_new_conf(conf_id);
		if (!conf)
			return(-EINVAL);
	}
	/* add conference member */
	err = dsp_cmx_add_conf_member(dsp, conf);
	if (err)
		return(err);
	dsp->conf_id = conf_id;

	/* if we are alone, we do nothing! */
	if (list_empty(&conf->mlist)) {
		if (dsp_debug & DEBUG_DSP_CMX)
			printk(KERN_DEBUG "we are alone in this conference, so exit.\n");
		/* update hardware */
		dsp_cmx_hardware(NULL, dsp);
		return(0);
	}

	/* update members on conf */
	dsp_cmx_hardware(conf, NULL);

	return(0);
}


/*
 * audio data is received from card
 */
void 
dsp_cmx_receive(dsp_t *dsp, struct sk_buff *skb)
{
//	s32 *c;
	u8 *d, *p;
	int len = skb->len;
	mISDN_head_t *hh = mISDN_HEAD_P(skb);
	int w, i, ii;
//	int direct = 0; /* use rx data to clock tx-data */

	/* check if we have sompen */
	if (len < 1)
		return;

#if 0
	/* check if we can use our clock and directly forward data */
	if (!dsp->features.has_jitter) {
		if (!conf)
			direct = 1;
		else {
			if (count_list_member(&conf->mlist) <= 2)
				direct = 1;
		}
	}
#endif

	/* half of the buffer should be larger than maximum packet size */
	if (len >= CMX_BUFF_HALF) {
		printk(KERN_ERR "%s line %d: packet from card is too large (%d bytes). please make card send smaller packets OR increase CMX_BUFF_SIZE\n", __FILE__, __LINE__, len);
		return;
	}

	/* initialize pointers if not already */
	if (dsp->rx_W < 0) {
		if (dsp->features.has_jitter)
			dsp->rx_R = dsp->rx_W = (hh->dinfo & CMX_BUFF_MASK);
		else
			dsp->rx_R = dsp->rx_W = 0;
	} else {
		if (dsp->features.has_jitter) {
			dsp->rx_W = (hh->dinfo & CMX_BUFF_MASK);
		}
		/* if we underrun (or maybe overrun), we set our new read pointer, and write silence to buffer */
		if (((dsp->rx_W-dsp->rx_R) & CMX_BUFF_MASK) >= CMX_BUFF_HALF) {
			if (dsp_debug & DEBUG_DSP_CMX)
				printk(KERN_DEBUG "cmx_receive(dsp=%lx): UNDERRUN (or overrun), adjusting read pointer! (inst %s)\n", (u_long)dsp, dsp->inst.name);
			dsp->rx_R = dsp->rx_W;
			memset(dsp->rx_buff, dsp_silence, sizeof(dsp->rx_buff));
		}
	}

	/* show where to write */
#ifdef CMX_DEBUG
	printk( KERN_DEBUG "cmx_receive(dsp=%lx): rx_R(dsp) rx_W(dsp)=%05x len=%d %s\n", (u_long)dsp, dsp->rx_R, dsp->rx_W, len, dsp->inst.name);
#endif

	/* write data into rx_buffer */
	p = skb->data;
	d = dsp->rx_buff;
	w = dsp->rx_W;
	i = 0;
	ii = len;
	while(i < ii) {
		d[w++ & CMX_BUFF_MASK] = *p++;
		i++;
	}

	/* increase write-pointer */
	dsp->rx_W = ((dsp->rx_W+len) & CMX_BUFF_MASK);
}


/*
 * send (mixed) audio data to card and control jitter
 */
static void
dsp_cmx_send_member(dsp_t *dsp, int len, s32 *c, int members)
{
	int dinfo = 0;
	conference_t *conf = dsp->conf;
	dsp_t *member, *other;
	register s32 sample;
	u8 *d, *p, *q, *o_q;
	struct sk_buff *nskb;
	int r, rr, t, tt, o_r, o_rr;
	
	/* don't process if: */
	if (dsp->pcm_slot_tx >= 0 /* connected to pcm slot */
	 && dsp->tx_R == dsp->tx_W /* AND no tx-data */
	 && !(dsp->tone.tone && dsp->tone.software)) /* AND not soft tones */
		return;
	if (!dsp->b_active) /* if not active */
		return;

// NOTE: The following is not good, because we MUST send transmit data or
//       software tones during pcm brige. (The condition above expresses this
//       exactly. The card driver MUST disable bridging if data is in TX-
//       fifo, to allow temporarily transmit tones until fifo is empty again.
#if 0
	/* If we have 2 members and we are connected to pcm_slot, it looks
	   like we're bridged on the pcm, so why should we send anything ? 
	   */
	if (	members==2 && (dsp->features.pcm_id>=0) && 
		(dsp->pcm_slot_tx>=0) && (dsp->pcm_slot_rx>=0) ) {
		return;
	}
#endif

#ifdef CMX_DEBUG
printk(KERN_DEBUG "SEND members=%d dsp=%s, conf=%p, rx_R=%05x rx_W=%05x\n", members, dsp->inst.name, conf, dsp->rx_R, dsp->rx_W);
#endif

	/* PREPARE RESULT */
	nskb = alloc_skb(len, GFP_ATOMIC);
	if (!nskb) {
		printk(KERN_ERR "FATAL ERROR in mISDN_dsp.o: cannot alloc %d bytes\n", len);
		return;
	}
	mISDN_sethead(PH_DATA | REQUEST, dinfo, nskb);

	/* set pointers, indexes and stuff */
	member = dsp;
	p = dsp->tx_buff; /* transmit data */
	q = dsp->rx_buff; /* received data */
	d = skb_put(nskb, len); /* result */
	t = dsp->tx_R; /* tx-pointers */
	tt = dsp->tx_W;
	r = dsp->rx_R; /* rx-pointers */
	rr = (r + len) & CMX_BUFF_MASK;

	/* PROCESS TONES/TX-DATA ONLY */
	if (dsp->tone.tone && dsp->tone.software) {
		/* -> copy tone */
		dsp_tone_copy(dsp, d, len);
		dsp->tx_R = dsp->tx_W = 0; /* clear tx buffer */
		goto send_packet;
	}
	/* if we have tx-data but do not use mixing */
	if (!dsp->tx_mix && t!=tt) {
		/* -> send tx-data and continue when not enough */
		while(r!=rr && t!=tt) {
			*d++ = p[t]; /* write tx_buff */
			t = (t+1) & CMX_BUFF_MASK;
			r = (r+1) & CMX_BUFF_MASK;
		}
		if(r == rr) {
			dsp->tx_R = t;
			goto send_packet;
		}
	}

	/* PROCESS DATA (one member / no conf) */
	if (!conf || members<=1) {
		/* -> if echo is NOT enabled */
		if (!dsp->echo) {
			/* -> send tx-data if available or use 0-volume */
			while(r!=rr && t!=tt) {
				*d++ = p[t]; /* write tx_buff */
				t = (t+1) & CMX_BUFF_MASK;
				r = (r+1) & CMX_BUFF_MASK;
			}
			if(r != rr)
				memset(d, dsp_silence, (rr-r)&CMX_BUFF_MASK);
		/* -> if echo is enabled */
		} else {
			/* -> mix tx-data with echo if available, or use echo only */
			while(r!=rr && t!=tt) {
				*d++ = dsp_audio_mix_law[(p[t]<<8)|q[r]];
				t = (t+1) & CMX_BUFF_MASK;
				r = (r+1) & CMX_BUFF_MASK;
			}
			while(r != rr) {
				*d++ = q[r]; /* echo */
				r = (r+1) & CMX_BUFF_MASK;
			}
		}
		dsp->tx_R = t;
		goto send_packet;
	}
	/* PROCESS DATA (two members) */
#ifdef CMX_CONF_DEBUG
	if (0) {
#else
	if (members == 2) {
#endif
		/* "other" becomes other party */
		other = (list_entry(conf->mlist.next, conf_member_t, list))->dsp;
		if (other == member)
			other = (list_entry(conf->mlist.prev, conf_member_t, list))->dsp;
		o_q = other->rx_buff; /* received data */
		o_r = other->rx_R; /* rx-pointers */
		o_rr = (o_r + len) & CMX_BUFF_MASK;
		/* -> if echo is NOT enabled */
		if (!dsp->echo) {
//if (o_r!=o_rr) printk(KERN_DEBUG "receive data=0x%02x\n", o_q[o_r]); else printk(KERN_DEBUG "NO R!!!\n");
			/* -> copy other member's rx-data, if tx-data is available, mix */
			while(o_r!=o_rr && t!=tt) {
				*d++ = dsp_audio_mix_law[(p[t]<<8)|o_q[o_r]];
				t = (t+1) & CMX_BUFF_MASK;
				o_r = (o_r+1) & CMX_BUFF_MASK;
			}
			while(o_r != o_rr) {
				*d++ = o_q[o_r];
				o_r = (o_r+1) & CMX_BUFF_MASK;
			}
		/* -> if echo is enabled */
		} else {
			/* -> mix other member's rx-data with echo, if tx-data is available, mix */
			while(r!=rr && t!=tt) {
				sample = dsp_audio_law_to_s32[p[t]] + dsp_audio_law_to_s32[q[r]] + dsp_audio_law_to_s32[o_q[o_r]];
				if (sample < -32768)
					sample = -32768;
				else if (sample > 32767)
					sample = 32767;
				*d++ = dsp_audio_s16_to_law[sample & 0xffff]; /* tx-data + rx_data + echo */
				t = (t+1) & CMX_BUFF_MASK;
				r = (r+1) & CMX_BUFF_MASK;
				o_r = (o_r+1) & CMX_BUFF_MASK;
			}
			while(r != rr) {
				*d++ = dsp_audio_mix_law[(q[r]<<8)|o_q[o_r]];
				r = (r+1) & CMX_BUFF_MASK;
				o_r = (o_r+1) & CMX_BUFF_MASK;
			}
		}
		dsp->tx_R = t;
		goto send_packet;
	}
	/* PROCESS DATA (three or more members) */
	/* -> if echo is NOT enabled */
	if (!dsp->echo) {
		/* -> substract rx-data from conf-data, if tx-data is available, mix */
		while(r!=rr && t!=tt) {
			sample = dsp_audio_law_to_s32[p[t]] + *c++ - dsp_audio_law_to_s32[q[r]];
			if (sample < -32768)
				sample = -32768;
			else if (sample > 32767)
				sample = 32767;
			*d++ = dsp_audio_s16_to_law[sample & 0xffff]; /* conf-rx+tx */
			r = (r+1) & CMX_BUFF_MASK;
			t = (t+1) & CMX_BUFF_MASK;
		}
		while(r != rr) {
			sample = *c++ - dsp_audio_law_to_s32[q[r]];
			if (sample < -32768)
				sample = -32768;
			else if (sample > 32767)
				sample = 32767;
			*d++ = dsp_audio_s16_to_law[sample & 0xffff]; /* conf-rx */
			r = (r+1) & CMX_BUFF_MASK;
		}
	/* -> if echo is enabled */
	} else {
		/* -> encode conf-data, if tx-data is available, mix */
		while(r!=rr && t!=tt) {
			sample = dsp_audio_law_to_s32[p[t]] + *c++;
			if (sample < -32768)
				sample = -32768;
			else if (sample > 32767)
				sample = 32767;
			*d++ = dsp_audio_s16_to_law[sample & 0xffff]; /* conf(echo)+tx */
			t = (t+1) & CMX_BUFF_MASK;
			r = (r+1) & CMX_BUFF_MASK;
		}
		while(r != rr) {
			sample = *c++;
			if (sample < -32768)
				sample = -32768;
			else if (sample > 32767)
				sample = 32767;
			*d++ = dsp_audio_s16_to_law[sample & 0xffff]; /* conf(echo) */
			r = (r+1) & CMX_BUFF_MASK;
		}
	}
	dsp->tx_R = t;
	goto send_packet;

send_packet:
	/* adjust volume */
	if (dsp->tx_volume)
		dsp_change_volume(nskb, dsp->tx_volume);
	
	/* cancel echo */
	if (dsp->cancel_enable)
		dsp_cancel_tx(dsp, nskb->data, nskb->len);
	
	/* crypt */
	if (dsp->bf_enable)
		dsp_bf_encrypt(dsp, nskb->data, nskb->len);
	
	/* send packet */
	if (mISDN_queue_down(&dsp->inst, 0, nskb)) {
		dev_kfree_skb(nskb);
		printk(KERN_ERR "%s: failed to send tx-packet\n", __FUNCTION__);
	}
}

u32	samplecount;
struct timer_list dsp_spl_tl;
u64	dsp_spl_jiffies;

void dsp_cmx_send(void *data)
{
	conference_t *conf;
	conf_member_t *member;
	dsp_t *dsp;
	int mustmix, members;
	s32 mixbuffer[MAX_POLL], *c;
	u8 *q;
	int r, rr;
	int jittercheck = 0, delay, i;
	u_long flags;

	/* lock */
	spin_lock_irqsave(&dsp_obj.lock, flags);

	/* check if jitter needs to be checked */
	samplecount += dsp_poll;
	if (samplecount%8000 < dsp_poll)
		jittercheck = 1;

	/* loop all members that do not require conference mixing */
	list_for_each_entry(dsp, &dsp_obj.ilist, list) {
		conf = dsp->conf;
		mustmix = 0;
		members = 0;
		if (conf) {
			members = count_list_member(&conf->mlist);
#ifdef CMX_CONF_DEBUG
			if (conf->software && members>1)
#else
			if (conf->software && members>2)
#endif
				mustmix = 1;
		}
		
		/* transmission required */
		if (!mustmix)
			dsp_cmx_send_member(dsp, dsp_poll, mixbuffer, members); // unused mixbuffer is given to prevent a potential null-pointer-bug
	}
	
	/* loop all members that require conference mixing */
	list_for_each_entry(conf, &Conf_list, list) {
		/* count members and check hardware */
		members = count_list_member(&conf->mlist);
#ifdef CMX_CONF_DEBUG
		if (conf->software && members>1) {
#else
		if (conf->software && members>2) {
#endif
			/* mix all data */
			memset(mixbuffer, 0, dsp_poll*sizeof(s32));
			list_for_each_entry(member, &conf->mlist, list) {
				dsp = member->dsp;
				/* get range of data to mix */
				c = mixbuffer;
				q = dsp->rx_buff;
				r = dsp->rx_R;
				rr = (r + dsp_poll) & CMX_BUFF_MASK;
				/* add member's data */
				while(r != rr) {
					*c++ += dsp_audio_law_to_s32[q[r]];
					r = (r+1) & CMX_BUFF_MASK;
				}
			}

			/* process each member */
			list_for_each_entry(member, &conf->mlist, list) {
				/* transmission */
				dsp_cmx_send_member(member->dsp, dsp_poll, mixbuffer, members);
			}
		}
	}

	/* delete rx-data, increment buffers, change pointers */
	list_for_each_entry(dsp, &dsp_obj.ilist, list) {
		q = dsp->rx_buff;
		r = dsp->rx_R;
		rr = (r + dsp_poll) & CMX_BUFF_MASK;
		/* delete rx-data */
		while(r != rr) {
			q[r] = dsp_silence;
			r = (r+1) & CMX_BUFF_MASK;
		}
		/* increment rx-buffer pointer */
		dsp->rx_R = r; /* write incremented read pointer */

		/* check current delay */
		delay = (dsp->rx_W-r) & CMX_BUFF_MASK;
		if (delay >= CMX_BUFF_HALF)
			delay = 0; /* will be the delay before next write */
		/* check for lower delay */
			if (delay < dsp->delay[0])
				dsp->delay[0] = delay;
		if (jittercheck) {
			/* find the lowest of all delays */
			delay = dsp->delay[0];
			i = 1;
			while (i < MAX_SECONDS_JITTER_CHECK) {
				if (delay > dsp->delay[i])
					delay = dsp->delay[i];
				i++;
			}
			/* remove delay */
			if (delay) {
				if (dsp_debug & DEBUG_DSP_CMX)
					printk(KERN_DEBUG "%s lowest delay of %d bytes for dsp %s are now removed.\n", __FUNCTION__, delay, dsp->inst.name);
				r = dsp->rx_R;
				rr = (r + delay) & CMX_BUFF_MASK;
				/* delete rx-data */
				while(r != rr) {
					q[r] = dsp_silence;
					r = (r+1) & CMX_BUFF_MASK;
				}
				/* increment rx-buffer pointer */
				dsp->rx_R = r; /* write incremented read pointer */
			}
			/* scroll up delays */
			i = MAX_SECONDS_JITTER_CHECK - 1;
			while (i) {
				dsp->delay[i] = dsp->delay[i-1];
				i--;
			}
			dsp->delay[0] = CMX_BUFF_HALF; /* (infinite) delay */
		}
	}

	/* restart timer */
//	init_timer(&dsp_spl_tl);
	if (dsp_spl_jiffies + dsp_tics < jiffies) /* if next event would be in the past ... */
		dsp_spl_jiffies = jiffies;
	else
		dsp_spl_jiffies += dsp_tics;

	dsp_spl_tl.expires = dsp_spl_jiffies;
	add_timer(&dsp_spl_tl);

	/* unlock */
	spin_unlock_irqrestore(&dsp_obj.lock, flags);
}

/*
 * audio data is transmitted from upper layer to the dsp
 */
void 
dsp_cmx_transmit(dsp_t *dsp, struct sk_buff *skb)
{
	u_int w, ww;
	u8 *d, *p;
	int space, l;

	/* check if we have sompen */
	l = skb->len;
	if (l < 1)
		return;

	/* check if there is enough space, and then copy */
	w = dsp->tx_W;
	ww = dsp->tx_R;
	p = dsp->tx_buff;
	d = skb->data;
	space = ww-w;
	if (space <= 0)
		space += CMX_BUFF_SIZE;
	/* write-pointer should not overrun nor reach read pointer */
	if (space-1 < skb->len)
		/* write to the space we have left */
		ww = (ww - 1) & CMX_BUFF_MASK;
	else
		/* write until all byte are copied */
		ww = (w + skb->len) & CMX_BUFF_MASK;
	dsp->tx_W = ww;

	/* show current buffer */
#ifdef CMX_DEBUG
	printk(KERN_DEBUG "cmx_transmit(dsp=%lx) %d bytes to 0x%x-0x%x. %s\n", (u_long)dsp, (ww-w)&CMX_BUFF_MASK, w, ww, dsp->inst.name);
#endif

	/* copy transmit data to tx-buffer */
	while(w != ww) {
		p[w]= *d++;
		w = (w+1) & CMX_BUFF_MASK;
	}

	return;
}