freeswitch/libs/freetdm/src/ozmod/ozmod_zt/ozmod_zt.c

/*
 * Copyright (c) 2007, Anthony Minessale II
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * * Neither the name of the original author; nor the names of any contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 * 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#include "openzap.h"
#include "ozmod_zt.h"


static struct {
	uint32_t codec_ms;
	uint32_t wink_ms;
	uint32_t flash_ms;
	uint32_t eclevel;
	uint32_t etlevel;
} zt_globals;

#define ZT_INVALID_SOCKET -1
static const char ctlpath[] = "/dev/zap/ctl";
static zap_socket_t CONTROL_FD = ZT_INVALID_SOCKET;

ZIO_SPAN_NEXT_EVENT_FUNCTION(zt_next_event);
ZIO_SPAN_POLL_EVENT_FUNCTION(zt_poll_event);

static unsigned zt_open_range(zap_span_t *span, unsigned start, unsigned end, zap_chan_type_t type, char *name, char *number)
{
	unsigned configured = 0, x;
	char path[] = "/dev/zap/channel";
	zt_params_t ztp;

	memset(&ztp, 0, sizeof(ztp));

	for(x = start; x < end; x++) {
		zap_channel_t *zchan;
		zap_socket_t sockfd = ZT_INVALID_SOCKET;
		int len;

		sockfd = open(path, O_RDWR);
		if (sockfd != ZT_INVALID_SOCKET && zap_span_add_channel(span, sockfd, type, &zchan) == ZAP_SUCCESS) {

			if (ioctl(sockfd, ZT_SPECIFY, &x)) {
				zap_log(ZAP_LOG_ERROR, "failure configuring device %s chan %d fd %d (%s)\n", path, x, sockfd, strerror(errno));
				close(sockfd);
				continue;
			}

			if (zchan->type == ZAP_CHAN_TYPE_DQ921) {
				struct zt_bufferinfo binfo;
				memset(&binfo, 0, sizeof(binfo));
				binfo.txbufpolicy = 0;
				binfo.rxbufpolicy = 0;
				binfo.numbufs = 32;
				binfo.bufsize = 1024;
				if (ioctl(sockfd, ZT_SET_BUFINFO, &binfo)) {
					zap_log(ZAP_LOG_ERROR, "failure configuring device %s as OpenZAP device %d:%d fd:%d\n", path, zchan->span_id, zchan->chan_id, sockfd);
					close(sockfd);
					continue;
				}
			}

			if (type == ZAP_CHAN_TYPE_FXS || type == ZAP_CHAN_TYPE_FXO) {
				struct zt_chanconfig cc;
				memset(&cc, 0, sizeof(cc));
				cc.chan = cc.master = x;
				
				switch(type) {
				case ZAP_CHAN_TYPE_FXS:
					{
						switch(span->start_type) {
						case ZAP_ANALOG_START_KEWL:
							cc.sigtype = ZT_SIG_FXOKS;
							break;
						case ZAP_ANALOG_START_LOOP:
							cc.sigtype = ZT_SIG_FXOLS;
							break;
						case ZAP_ANALOG_START_GROUND:
							cc.sigtype = ZT_SIG_FXOGS;
							break;
						default:
							break;
						}
					}
					break;
				case ZAP_CHAN_TYPE_FXO:
					{
						switch(span->start_type) {
						case ZAP_ANALOG_START_KEWL:
							cc.sigtype = ZT_SIG_FXSKS;
							break;
						case ZAP_ANALOG_START_LOOP:
							cc.sigtype = ZT_SIG_FXSLS;
							break;
						case ZAP_ANALOG_START_GROUND:
							cc.sigtype = ZT_SIG_FXSGS;
							break;
						default:
							break;
						}
					}
					break;
				default:
					break;
				}
				
				if (ioctl(CONTROL_FD, ZT_CHANCONFIG, &cc)) {
					zap_log(ZAP_LOG_WARNING, "this ioctl fails on older zaptel but is harmless if you used ztcfg\n[device %s chan %d fd %d (%s)]\n", path, x, CONTROL_FD, strerror(errno));
				}
			}

			if (zchan->type != ZAP_CHAN_TYPE_DQ921 && zchan->type != ZAP_CHAN_TYPE_DQ931) {
				len = zt_globals.codec_ms * 8;
				if (ioctl(zchan->sockfd, ZT_SET_BLOCKSIZE, &len)) {
					zap_log(ZAP_LOG_ERROR, "failure configuring device %s as OpenZAP device %d:%d fd:%d err:%s\n", 
							path, zchan->span_id, zchan->chan_id, sockfd, strerror(errno));
					close(sockfd);
					continue;
				}

				zchan->packet_len = len;
				zchan->effective_interval = zchan->native_interval = zchan->packet_len / 8;
			
				if (zchan->effective_codec == ZAP_CODEC_SLIN) {
					zchan->packet_len *= 2;
				}
			}
			
			if (ioctl(sockfd, ZT_GET_PARAMS, &ztp) < 0) {
				zap_log(ZAP_LOG_ERROR, "failure configuring device %s as OpenZAP device %d:%d fd:%d\n", path, zchan->span_id, zchan->chan_id, sockfd);
				close(sockfd);
				continue;
			}

			if (zchan->type == ZAP_CHAN_TYPE_DQ921) {
				if ((ztp.sig_type != ZT_SIG_HDLCRAW) && (ztp.sig_type != ZT_SIG_HDLCFCS)) {
					zap_log(ZAP_LOG_ERROR, "failure configuring device %s as OpenZAP device %d:%d fd:%d\n", path, zchan->span_id, zchan->chan_id, sockfd);
					close(sockfd);
					continue;
				}
			}

			zap_log(ZAP_LOG_INFO, "configuring device %s channel %d as OpenZAP device %d:%d fd:%d\n", path, x, zchan->span_id, zchan->chan_id, sockfd);
			
			zchan->rate = 8000;
			zchan->physical_span_id = ztp.span_no;
			zchan->physical_chan_id = ztp.chan_no;
			
			if (type == ZAP_CHAN_TYPE_FXS || type == ZAP_CHAN_TYPE_FXO || type == ZAP_CHAN_TYPE_EM || type == ZAP_CHAN_TYPE_B) {
				if (ztp.g711_type == ZT_G711_ALAW) {
					zchan->native_codec = zchan->effective_codec = ZAP_CODEC_ALAW;
				} else if (ztp.g711_type == ZT_G711_MULAW) {
					zchan->native_codec = zchan->effective_codec = ZAP_CODEC_ULAW;
				} else {
					int type;

					if (zchan->span->trunk_type == ZAP_TRUNK_E1) {
						type = ZAP_CODEC_ALAW;
					} else {
						type = ZAP_CODEC_ULAW;
					}

					zchan->native_codec = zchan->effective_codec = type;

				}
			}
			

			ztp.wink_time = zt_globals.wink_ms;
			ztp.flash_time = zt_globals.flash_ms;

			if (ioctl(sockfd, ZT_SET_PARAMS, &ztp) < 0) {
				zap_log(ZAP_LOG_ERROR, "failure configuring device %s as OpenZAP device %d:%d fd:%d\n", path, zchan->span_id, zchan->chan_id, sockfd);
				close(sockfd);
				continue;
			}
		

			if (!zap_strlen_zero(name)) {
				zap_copy_string(zchan->chan_name, name, sizeof(zchan->chan_name));
			}
			if (!zap_strlen_zero(number)) {
				zap_copy_string(zchan->chan_number, number, sizeof(zchan->chan_number));
			}
			configured++;
		} else {
			zap_log(ZAP_LOG_ERROR, "failure configuring device %s\n", path);
		}
	}
	


	return configured;
}

static ZIO_CONFIGURE_SPAN_FUNCTION(zt_configure_span)
{

	int items, i;
    char *mydata, *item_list[10];
	char *ch, *mx;
	int channo;
	int top = 0;
	unsigned configured = 0;

	assert(str != NULL);
	

	mydata = strdup(str);
	assert(mydata != NULL);


	items = zap_separate_string(mydata, ',', item_list, (sizeof(item_list) / sizeof(item_list[0])));

	for(i = 0; i < items; i++) {
		ch = item_list[i];

		if (!(ch)) {
			zap_log(ZAP_LOG_ERROR, "Invalid input\n");
			continue;
		}

		channo = atoi(ch);
		
		if (channo < 0) {
			zap_log(ZAP_LOG_ERROR, "Invalid channel number %d\n", channo);
			continue;
		}

		if ((mx = strchr(ch, '-'))) {
			mx++;
			top = atoi(mx) + 1;
		} else {
			top = channo + 1;
		}
		
		
		if (top < 0) {
			zap_log(ZAP_LOG_ERROR, "Invalid range number %d\n", top);
			continue;
		}

		configured += zt_open_range(span, channo, top, type, name, number);

	}
	
	free(mydata);

	return configured;

}

static ZIO_CONFIGURE_FUNCTION(zt_configure)
{

	int num;

	if (!strcasecmp(category, "defaults")) {
		if (!strcasecmp(var, "codec_ms")) {
			num = atoi(val);
			if (num < 10 || num > 60) {
				zap_log(ZAP_LOG_WARNING, "invalid codec ms at line %d\n", lineno);
			} else {
				zt_globals.codec_ms = num;
			}
		} else if (!strcasecmp(var, "wink_ms")) {
			num = atoi(val);
			if (num < 50 || num > 3000) {
				zap_log(ZAP_LOG_WARNING, "invalid wink ms at line %d\n", lineno);
			} else {
				zt_globals.wink_ms = num;
			}
		} else if (!strcasecmp(var, "flash_ms")) {
			num = atoi(val);
			if (num < 50 || num > 3000) {
				zap_log(ZAP_LOG_WARNING, "invalid flash ms at line %d\n", lineno);
			} else {
				zt_globals.flash_ms = num;
			}
		} else if (!strcasecmp(var, "echo_cancel_level")) {
			num = atoi(val);
			if (num < 0 || num > 256) {
                zap_log(ZAP_LOG_WARNING, "invalid echo can val at line %d\n", lineno);
            } else {
                zt_globals.eclevel = num;
            }
			
		}
	}

	return ZAP_SUCCESS;
}

static ZIO_OPEN_FUNCTION(zt_open) 
{
	zap_channel_set_feature(zchan, ZAP_CHANNEL_FEATURE_INTERVAL);

	if (zchan->type == ZAP_CHAN_TYPE_DQ921 || zchan->type == ZAP_CHAN_TYPE_DQ931) {
		zchan->native_codec = zchan->effective_codec = ZAP_CODEC_NONE;
	} else {
		int blocksize = zt_globals.codec_ms * (zchan->rate / 1000);
		int err;
		if ((err = ioctl(zchan->sockfd, ZT_SET_BLOCKSIZE, &blocksize))) {
			snprintf(zchan->last_error, sizeof(zchan->last_error), "%s", strerror(errno));
			return ZAP_FAIL;
		} else {
			zchan->effective_interval = zchan->native_interval;
			zchan->packet_len = blocksize;
			zchan->native_codec = zchan->effective_codec;
		}
		
		if (zchan->type == ZAP_CHAN_TYPE_B) {
			int one = 1;
			if (ioctl(zchan->sockfd, ZT_AUDIOMODE, &one)) {
				snprintf(zchan->last_error, sizeof(zchan->last_error), "%s", strerror(errno));
				zap_log(ZAP_LOG_ERROR, "%s\n", zchan->last_error);
				return ZAP_FAIL;
			}
		} else if (zchan->type == ZAP_CHAN_TYPE_FXS || zchan->type == ZAP_CHAN_TYPE_FXO || zchan->type == ZAP_CHAN_TYPE_EM) {
			int len = zt_globals.eclevel;
			if (ioctl(zchan->sockfd, ZT_ECHOCANCEL, &len)) {
				zap_log(ZAP_LOG_WARNING, "Echo cancel not available for %d:%d\n", zchan->span_id, zchan->chan_id);
				//snprintf(zchan->last_error, sizeof(zchan->last_error), "%s", strerror(errno));
				//zap_log(ZAP_LOG_ERROR, "%s\n", zchan->last_error);
				//return ZAP_FAIL;
			} else {
				len = zt_globals.etlevel;
				if (ioctl(zchan->sockfd, ZT_ECHOTRAIN, &len)) {
					zap_log(ZAP_LOG_WARNING, "Echo training not available for %d:%d\n", zchan->span_id, zchan->chan_id);
					//snprintf(zchan->last_error, sizeof(zchan->last_error), "%s", strerror(errno));
					//zap_log(ZAP_LOG_ERROR, "%s\n", zchan->last_error);
					//return ZAP_FAIL;
				}
			}
		}
	}
	return ZAP_SUCCESS;
}

static ZIO_CLOSE_FUNCTION(zt_close)
{
	return ZAP_SUCCESS;
}

static ZIO_COMMAND_FUNCTION(zt_command)
{
	zt_params_t ztp;
	int err = 0;

	memset(&ztp, 0, sizeof(ztp));

	switch(command) {
	case ZAP_COMMAND_ENABLE_ECHOCANCEL:
		{
			int level = ZAP_COMMAND_OBJ_INT;
			err = ioctl(zchan->sockfd, ZT_ECHOCANCEL, &level);
			ZAP_COMMAND_OBJ_INT = level;
		}
	case ZAP_COMMAND_DISABLE_ECHOCANCEL:
		{
			int level = 0;
			err = ioctl(zchan->sockfd, ZT_ECHOCANCEL, &level);
			ZAP_COMMAND_OBJ_INT = level;
		}
		break;
	case ZAP_COMMAND_ENABLE_ECHOTRAIN:
		{
			int level = ZAP_COMMAND_OBJ_INT;
			err = ioctl(zchan->sockfd, ZT_ECHOTRAIN, &level);
			ZAP_COMMAND_OBJ_INT = level;
		}
	case ZAP_COMMAND_DISABLE_ECHOTRAIN:
		{
			int level = 0;
			err = ioctl(zchan->sockfd, ZT_ECHOTRAIN, &level);
			ZAP_COMMAND_OBJ_INT = level;
		}
		break;
	case ZAP_COMMAND_OFFHOOK:
		{
			int command = ZT_OFFHOOK;
			if (ioctl(zchan->sockfd, ZT_HOOK, &command)) {
				snprintf(zchan->last_error, sizeof(zchan->last_error), "OFFHOOK Failed");
				return ZAP_FAIL;
			}
			zap_set_flag_locked(zchan, ZAP_CHANNEL_OFFHOOK);
		}
		break;
	case ZAP_COMMAND_ONHOOK:
		{
			int command = ZT_ONHOOK;
			if (ioctl(zchan->sockfd, ZT_HOOK, &command)) {
				snprintf(zchan->last_error, sizeof(zchan->last_error), "ONHOOK Failed");
				return ZAP_FAIL;
			}
			zap_clear_flag_locked(zchan, ZAP_CHANNEL_OFFHOOK);
		}
		break;
	case ZAP_COMMAND_GENERATE_RING_ON:
		{
			int command = ZT_RING;
			if (ioctl(zchan->sockfd, ZT_HOOK, &command)) {
				snprintf(zchan->last_error, sizeof(zchan->last_error), "Ring Failed");
				return ZAP_FAIL;
			}
			zap_set_flag_locked(zchan, ZAP_CHANNEL_RINGING);
		}
		break;
	case ZAP_COMMAND_GENERATE_RING_OFF:
		{
			int command = ZT_RINGOFF;
			if (ioctl(zchan->sockfd, ZT_HOOK, &command)) {
				snprintf(zchan->last_error, sizeof(zchan->last_error), "Ring-off failed");
				return ZAP_FAIL;
			}
			zap_clear_flag_locked(zchan, ZAP_CHANNEL_RINGING);
		}
		break;
	case ZAP_COMMAND_GET_INTERVAL:
		{

			if (!(err = ioctl(zchan->sockfd, ZT_GET_BLOCKSIZE, &zchan->packet_len))) {
				zchan->native_interval = zchan->packet_len / 8;
				if (zchan->effective_codec == ZAP_CODEC_SLIN) {
					zchan->packet_len *= 2;
				}
				ZAP_COMMAND_OBJ_INT = zchan->native_interval;
			} 			
		}
		break;
	case ZAP_COMMAND_SET_INTERVAL: 
		{
			int interval = ZAP_COMMAND_OBJ_INT;
			int len = interval * 8;

			if (!(err = ioctl(zchan->sockfd, ZT_SET_BLOCKSIZE, &len))) {
				zchan->packet_len = len;
				zchan->effective_interval = zchan->native_interval = zchan->packet_len / 8;

                if (zchan->effective_codec == ZAP_CODEC_SLIN) {
                    zchan->packet_len *= 2;
                }

			}
		}
		break;
	default:
		break;
	};

	if (err) {
		snprintf(zchan->last_error, sizeof(zchan->last_error), "%s", strerror(errno));
		return ZAP_FAIL;
	}


	return ZAP_SUCCESS;
}

static ZIO_GET_ALARMS_FUNCTION(zt_get_alarms)
{
	struct zt_spaninfo info;

	memset(&info, 0, sizeof(info));
	info.span_no = zchan->physical_span_id;

	if (ioctl(CONTROL_FD, ZT_SPANSTAT, &info)) {
		snprintf(zchan->last_error, sizeof(zchan->last_error), "ioctl failed (%s)", strerror(errno));
		snprintf(zchan->span->last_error, sizeof(zchan->span->last_error), "ioctl failed (%s)", strerror(errno));
		return ZAP_FAIL;
	}

	zchan->alarm_flags = info.alarms;

	return ZAP_SUCCESS;
}


static ZIO_WAIT_FUNCTION(zt_wait)
{
	int32_t inflags = 0;
	int result;
    struct pollfd pfds[1];

	if (*flags & ZAP_READ) {
		inflags |= POLLIN;
	}

	if (*flags & ZAP_WRITE) {
		inflags |= POLLOUT;
	}

	if (*flags & ZAP_EVENTS) {
		inflags |= POLLPRI;
	}


    memset(&pfds[0], 0, sizeof(pfds[0]));
    pfds[0].fd = zchan->sockfd;
    pfds[0].events = inflags;
    result = poll(pfds, 1, to);
	*flags = 0;

	if (pfds[0].revents & POLLERR) {
		result = -1;
	}

	if (result > 0) {
		inflags = pfds[0].revents;
	}

	*flags = ZAP_NO_FLAGS;

	if (result < 0){
		snprintf(zchan->last_error, sizeof(zchan->last_error), "Poll failed");
		return ZAP_FAIL;
	}

	if (result == 0) {
		return ZAP_TIMEOUT;
	}

	if (inflags & POLLIN) {
		*flags |= ZAP_READ;
	}

	if (inflags & POLLOUT) {
		*flags |= ZAP_WRITE;
	}

	if (inflags & POLLPRI) {
		*flags |= ZAP_EVENTS;
	}

	return ZAP_SUCCESS;

}

ZIO_SPAN_POLL_EVENT_FUNCTION(zt_poll_event)
{
	struct pollfd pfds[ZAP_MAX_CHANNELS_SPAN];
	uint32_t i, j = 0, k = 0;
	int r;
	
	for(i = 1; i <= span->chan_count; i++) {
		memset(&pfds[j], 0, sizeof(pfds[j]));
		pfds[j].fd = span->channels[i]->sockfd;
		pfds[j].events = POLLPRI;
		j++;
	}

    r = poll(pfds, j, ms);

	if (r == 0) {
		return ZAP_TIMEOUT;
	} else if (r < 0 || (pfds[i-1].revents & POLLERR)) {
		snprintf(span->last_error, sizeof(span->last_error), "%s", strerror(errno));
		return ZAP_FAIL;
	}
	
	for(i = 1; i <= span->chan_count; i++) {
		if (pfds[i-1].revents & POLLPRI) {
			zap_set_flag(span->channels[i], ZAP_CHANNEL_EVENT);
			span->channels[i]->last_event_time = zap_current_time_in_ms();
			k++;
		}
	}

	if (!k) {
		snprintf(span->last_error, sizeof(span->last_error), "no matching descriptor");
	}

	return k ? ZAP_SUCCESS : ZAP_FAIL;
}

ZIO_SPAN_NEXT_EVENT_FUNCTION(zt_next_event)
{
	uint32_t i, event_id = 0;
	zap_oob_event_t zt_event_id = 0;

	for(i = 1; i <= span->chan_count; i++) {
		if (zap_test_flag(span->channels[i], ZAP_CHANNEL_EVENT)) {
			zap_clear_flag(span->channels[i], ZAP_CHANNEL_EVENT);
			if (ioctl(span->channels[i]->sockfd, ZT_GETEVENT, &zt_event_id) == -1) {
				snprintf(span->last_error, sizeof(span->last_error), "%s", strerror(errno));
				return ZAP_FAIL;
			}

			switch(zt_event_id) {
			case ZT_EVENT_RINGEROFF:
				{
					return ZAP_FAIL;
				}
				break;
			case ZT_EVENT_RINGERON:
				{
					return ZAP_FAIL;
				}
				break;
			case ZT_EVENT_RINGBEGIN:
				{
					event_id = ZAP_OOB_RING_START;
				}
				break;
			case ZT_EVENT_ONHOOK:
				{
					event_id = ZAP_OOB_ONHOOK;
				}
				break;
			case ZT_EVENT_WINKFLASH:
				{
					if (span->channels[i]->state == ZAP_CHANNEL_STATE_DOWN || span->channels[i]->state == ZAP_CHANNEL_STATE_DIALING) {
						event_id = ZAP_OOB_WINK;
					} else {
						event_id = ZAP_OOB_FLASH;
					}
				}
				break;
			case ZT_EVENT_RINGOFFHOOK:
				{
					if (span->channels[i]->type == ZAP_CHAN_TYPE_FXS || (span->channels[i]->type == ZAP_CHAN_TYPE_EM && span->channels[i]->state != ZAP_CHANNEL_STATE_UP)) {
						zap_set_flag_locked(span->channels[i], ZAP_CHANNEL_OFFHOOK);
						event_id = ZAP_OOB_OFFHOOK;
					} else if (span->channels[i]->type == ZAP_CHAN_TYPE_FXO) {
						event_id = ZAP_OOB_RING_START;
					}
				}
				break;
			case ZT_EVENT_ALARM:
				{
					event_id = ZAP_OOB_ALARM_TRAP;
				}
				break;
			case ZT_EVENT_NOALARM:
				{
					event_id = ZAP_OOB_ALARM_CLEAR;
				}
				break;
			default:
				{
					zap_log(ZAP_LOG_WARNING, "Unhandled event %d\n", zt_event_id);
					event_id = ZAP_OOB_INVALID;
				}
				break;
			}

			span->channels[i]->last_event_time = 0;
			span->event_header.e_type = ZAP_EVENT_OOB;
			span->event_header.enum_id = event_id;
			span->event_header.channel = span->channels[i];
			*event = &span->event_header;
			return ZAP_SUCCESS;
		}
	}

	return ZAP_FAIL;
	
}


static ZIO_READ_FUNCTION(zt_read)
{
	zap_ssize_t r = 0;
	int errs = 0;

	while (errs++ < 100) {
		if ((r = read(zchan->sockfd, data, *datalen)) > 0) {
			break;
		}
	}

	if (r > 0) {
		*datalen = r;
		if (zchan->type == ZAP_CHAN_TYPE_DQ921) {
			*datalen -= 2;
		}
		return ZAP_SUCCESS;
	}

	return ZAP_FAIL;
}

static ZIO_WRITE_FUNCTION(zt_write)
{
	zap_ssize_t w = 0;
	zap_size_t bytes = *datalen;

	if (zchan->type == ZAP_CHAN_TYPE_DQ921) {
		memset(data+bytes, 0, 2);
		bytes += 2;
	}

	w = write(zchan->sockfd, data, bytes);
	
	if (w >= 0) {
		*datalen = w;
		return ZAP_SUCCESS;
	}

	return ZAP_FAIL;
}

static ZIO_CHANNEL_DESTROY_FUNCTION(zt_channel_destroy)
{
	close(zchan->sockfd);
	zchan->sockfd = ZT_INVALID_SOCKET;

	return ZAP_SUCCESS;
}

static zap_io_interface_t zt_interface;

static ZIO_IO_LOAD_FUNCTION(zt_init)
{
	assert(zio != NULL);
	memset(&zt_interface, 0, sizeof(zt_interface));
	memset(&zt_globals, 0, sizeof(zt_globals));

	if ((CONTROL_FD = open(ctlpath, O_RDWR)) < 0) {
		zap_log(ZAP_LOG_ERROR, "Cannot open control device\n");
		return ZAP_FAIL;
	}

	zt_globals.codec_ms = 20;
	zt_globals.wink_ms = 150;
	zt_globals.flash_ms = 750;
	zt_globals.eclevel = 64;
	zt_globals.etlevel = 0;
	
	zt_interface.name = "zt";
	zt_interface.configure = zt_configure;
	zt_interface.configure_span = zt_configure_span;
	zt_interface.open = zt_open;
	zt_interface.close = zt_close;
	zt_interface.command = zt_command;
	zt_interface.wait = zt_wait;
	zt_interface.read = zt_read;
	zt_interface.write = zt_write;
	zt_interface.poll_event = zt_poll_event;
	zt_interface.next_event = zt_next_event;
	zt_interface.channel_destroy = zt_channel_destroy;
	zt_interface.get_alarms = zt_get_alarms;
	*zio = &zt_interface;

	return ZAP_SUCCESS;
}

static ZIO_IO_UNLOAD_FUNCTION(zt_destroy)
{
	close(CONTROL_FD);
	memset(&zt_interface, 0, sizeof(zt_interface));
	return ZAP_SUCCESS;
}


zap_module_t zap_module = { 
	"zt",
	zt_init,
	zt_destroy,
};

/* For Emacs:
 * Local Variables:
 * mode:c
 * indent-tabs-mode:t
 * tab-width:4
 * c-basic-offset:4
 * End:
 * For VIM:
 * vim:set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:
 */