rdesktop/trunk/rdpsnd.c

/* -*- c-basic-offset: 8 -*-
   rdesktop: A Remote Desktop Protocol client.
   Sound Channel Process Functions
   Copyright (C) Matthew Chapman 2003
   Copyright (C) GuoJunBo guojunbo@ict.ac.cn 2003

   This program 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.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "rdesktop.h"
#include "rdpsnd.h"
#include "rdpsnd_dsp.h"

#define RDPSND_CLOSE            1
#define RDPSND_WRITE            2
#define RDPSND_SET_VOLUME       3
#define RDPSND_UNKNOWN4         4
#define RDPSND_COMPLETION       5
#define RDPSND_SERVERTICK       6
#define RDPSND_NEGOTIATE        7

#define MAX_FORMATS             10
#define MAX_QUEUE               10

BOOL g_dsp_busy = False;
int g_dsp_fd;

static VCHANNEL *rdpsnd_channel;
static struct audio_driver *drivers = NULL;
struct audio_driver *current_driver = NULL;

static BOOL device_open;
static WAVEFORMATEX formats[MAX_FORMATS];
static unsigned int format_count;
static unsigned int current_format;
unsigned int queue_hi, queue_lo;
struct audio_packet packet_queue[MAX_QUEUE];

void (*wave_out_play) (void);

static STREAM
rdpsnd_init_packet(uint16 type, uint16 size)
{
        STREAM s;

        s = channel_init(rdpsnd_channel, size + 4);
        out_uint16_le(s, type);
        out_uint16_le(s, size);
        return s;
}

static void
rdpsnd_send(STREAM s)
{
#ifdef RDPSND_DEBUG
        printf("RDPSND send:\n");
        hexdump(s->channel_hdr + 8, s->end - s->channel_hdr - 8);
#endif

        channel_send(s, rdpsnd_channel);
}

void
rdpsnd_send_completion(uint16 tick, uint8 packet_index)
{
        STREAM s;

        s = rdpsnd_init_packet(RDPSND_COMPLETION, 4);
        out_uint16_le(s, tick);
        out_uint8(s, packet_index);
        out_uint8(s, 0);
        s_mark_end(s);
        rdpsnd_send(s);
}

static void
rdpsnd_process_negotiate(STREAM in)
{
        unsigned int in_format_count, i;
        WAVEFORMATEX *format;
        STREAM out;
        BOOL device_available = False;
        int readcnt;
        int discardcnt;

        in_uint8s(in, 14);      /* flags, volume, pitch, UDP port */
        in_uint16_le(in, in_format_count);
        in_uint8s(in, 4);       /* pad, status, pad */

        if (current_driver->wave_out_open())
        {
                current_driver->wave_out_close();
                device_available = True;
        }

        format_count = 0;
        if (s_check_rem(in, 18 * in_format_count))
        {
                for (i = 0; i < in_format_count; i++)
                {
                        format = &formats[format_count];
                        in_uint16_le(in, format->wFormatTag);
                        in_uint16_le(in, format->nChannels);
                        in_uint32_le(in, format->nSamplesPerSec);
                        in_uint32_le(in, format->nAvgBytesPerSec);
                        in_uint16_le(in, format->nBlockAlign);
                        in_uint16_le(in, format->wBitsPerSample);
                        in_uint16_le(in, format->cbSize);

                        /* read in the buffer of unknown use */
                        readcnt = format->cbSize;
                        discardcnt = 0;
                        if (format->cbSize > MAX_CBSIZE)
                        {
                                fprintf(stderr, "cbSize too large for buffer: %d\n",
                                        format->cbSize);
                                readcnt = MAX_CBSIZE;
                                discardcnt = format->cbSize - MAX_CBSIZE;
                        }
                        in_uint8a(in, format->cb, readcnt);
                        in_uint8s(in, discardcnt);

                        if (device_available && current_driver->wave_out_format_supported(format))
                        {
                                format_count++;
                                if (format_count == MAX_FORMATS)
                                        break;
                        }
                }
        }

        out = rdpsnd_init_packet(RDPSND_NEGOTIATE | 0x200, 20 + 18 * format_count);
        out_uint32_le(out, 3);  /* flags */
        out_uint32(out, 0xffffffff);    /* volume */
        out_uint32(out, 0);     /* pitch */
        out_uint16(out, 0);     /* UDP port */

        out_uint16_le(out, format_count);
        out_uint8(out, 0x95);   /* pad? */
        out_uint16_le(out, 2);  /* status */
        out_uint8(out, 0x77);   /* pad? */

        for (i = 0; i < format_count; i++)
        {
                format = &formats[i];
                out_uint16_le(out, format->wFormatTag);
                out_uint16_le(out, format->nChannels);
                out_uint32_le(out, format->nSamplesPerSec);
                out_uint32_le(out, format->nAvgBytesPerSec);
                out_uint16_le(out, format->nBlockAlign);
                out_uint16_le(out, format->wBitsPerSample);
                out_uint16(out, 0);     /* cbSize */
        }

        s_mark_end(out);
        rdpsnd_send(out);
}

static void
rdpsnd_process_servertick(STREAM in)
{
        uint16 tick1, tick2;
        STREAM out;

        /* in_uint8s(in, 4); unknown */
        in_uint16_le(in, tick1);
        in_uint16_le(in, tick2);

        out = rdpsnd_init_packet(RDPSND_SERVERTICK | 0x2300, 4);
        out_uint16_le(out, tick1);
        out_uint16_le(out, tick2);
        s_mark_end(out);
        rdpsnd_send(out);
}

static void
rdpsnd_process(STREAM s)
{
        uint8 type;
        uint16 datalen;
        uint32 volume;
        static uint16 tick, format;
        static uint8 packet_index;
        static BOOL awaiting_data_packet;

#ifdef RDPSND_DEBUG
        printf("RDPSND recv:\n");
        hexdump(s->p, s->end - s->p);
#endif

        if (awaiting_data_packet)
        {
                if (format >= MAX_FORMATS)
                {
                        error("RDPSND: Invalid format index\n");
                        return;
                }

                if (!device_open || (format != current_format))
                {
                        if (!device_open && !current_driver->wave_out_open())
                        {
                                rdpsnd_send_completion(tick, packet_index);
                                return;
                        }
                        if (!current_driver->wave_out_set_format(&formats[format]))
                        {
                                rdpsnd_send_completion(tick, packet_index);
                                current_driver->wave_out_close();
                                device_open = False;
                                return;
                        }
                        device_open = True;
                        current_format = format;
                }

                current_driver->
                        wave_out_write(rdpsnd_dsp_process
                                       (s, current_driver, &formats[current_format]), tick,
                                       packet_index);
                awaiting_data_packet = False;
                return;
        }

        in_uint8(s, type);
        in_uint8s(s, 1);        /* unknown? */
        in_uint16_le(s, datalen);

        switch (type)
        {
                case RDPSND_WRITE:
                        in_uint16_le(s, tick);
                        in_uint16_le(s, format);
                        in_uint8(s, packet_index);
                        awaiting_data_packet = True;
                        break;
                case RDPSND_CLOSE:
                        current_driver->wave_out_close();
                        device_open = False;
                        break;
                case RDPSND_NEGOTIATE:
                        rdpsnd_process_negotiate(s);
                        break;
                case RDPSND_SERVERTICK:
                        rdpsnd_process_servertick(s);
                        break;
                case RDPSND_SET_VOLUME:
                        in_uint32(s, volume);
                        if (device_open)
                        {
                                current_driver->wave_out_volume((volume & 0xffff),
                                                                (volume & 0xffff0000) >> 16);
                        }
                        break;
                default:
                        unimpl("RDPSND packet type %d\n", type);
                        break;
        }
}

BOOL
rdpsnd_init(void)
{
        rdpsnd_channel =
                channel_register("rdpsnd", CHANNEL_OPTION_INITIALIZED | CHANNEL_OPTION_ENCRYPT_RDP,
                                 rdpsnd_process);

        return (rdpsnd_channel != NULL);
}

BOOL
rdpsnd_auto_open(void)
{
        current_driver = drivers;
        while (current_driver != NULL)
        {
                DEBUG(("trying %s...\n", current_driver->name));
                if (current_driver->wave_out_open())
                {
                        DEBUG(("selected %s\n", current_driver->name));
                        return True;
                }
                g_dsp_fd = 0;
                current_driver = current_driver->next;
        }

        warning("no working audio-driver found\n");

        return False;
}

void
rdpsnd_register_drivers(char *options)
{
        struct audio_driver **reg;

        /* The order of registrations define the probe-order
           when opening the device for the first time */
        reg = &drivers;
#if defined(RDPSND_ALSA)
        *reg = alsa_register(options);
        reg = &((*reg)->next);
#endif
#if defined(RDPSND_OSS)
        *reg = oss_register(options);
        reg = &((*reg)->next);
#endif
#if defined(RDPSND_SUN)
        *reg = sun_register(options);
        reg = &((*reg)->next);
#endif
#if defined(RDPSND_SGI)
        *reg = sgi_register(options);
        reg = &((*reg)->next);
#endif
#if defined(RDPSND_LIBAO)
        *reg = libao_register(options);
        reg = &((*reg)->next);
#endif
}

BOOL
rdpsnd_select_driver(char *driver, char *options)
{
        static struct audio_driver auto_driver;
        struct audio_driver *pos;

        drivers = NULL;
        rdpsnd_register_drivers(options);

        if (!driver)
        {
                auto_driver.wave_out_open = &rdpsnd_auto_open;
                current_driver = &auto_driver;
                return True;
        }

        pos = drivers;
        while (pos != NULL)
        {
                if (!strcmp(pos->name, driver))
                {
                        DEBUG(("selected %s\n", pos->name));
                        current_driver = pos;
                        return True;
                }
                pos = pos->next;
        }
        return False;
}

void
rdpsnd_show_help(void)
{
        struct audio_driver *pos;

        rdpsnd_register_drivers(NULL);

        pos = drivers;
        while (pos != NULL)
        {
                fprintf(stderr, "                     %s:\t%s\n", pos->name, pos->description);
                pos = pos->next;
        }
}

inline void
rdpsnd_play(void)
{
        current_driver->wave_out_play();
}

void
rdpsnd_queue_write(STREAM s, uint16 tick, uint8 index)
{
        struct audio_packet *packet = &packet_queue[queue_hi];
        unsigned int next_hi = (queue_hi + 1) % MAX_QUEUE;

        if (next_hi == queue_lo)
        {
                error("No space to queue audio packet\n");
                return;
        }

        queue_hi = next_hi;

        packet->s = *s;
        packet->tick = tick;
        packet->index = index;

        if (!g_dsp_busy)
                current_driver->wave_out_play();
}

inline struct audio_packet *
rdpsnd_queue_current_packet(void)
{
        return &packet_queue[queue_lo];
}

inline BOOL
rdpsnd_queue_empty(void)
{
        return (queue_lo == queue_hi);
}

inline void
rdpsnd_queue_init(void)
{
        queue_lo = queue_hi = 0;
}

inline void
rdpsnd_queue_next(void)
{
        xfree(packet_queue[queue_lo].s.data);
        queue_lo = (queue_lo + 1) % MAX_QUEUE;
}

inline int
rdpsnd_queue_next_tick(void)
{
        if (((queue_lo + 1) % MAX_QUEUE) != queue_hi)
        {
                return packet_queue[(queue_lo + 1) % MAX_QUEUE].tick;
        }
        else
        {
                return (packet_queue[queue_lo].tick + 65535) % 65536;
        }
}
1	/* -- c-basic-offset: 8 --
2	rdesktop: A Remote Desktop Protocol client.
3	Sound Channel Process Functions
4	Copyright (C) Matthew Chapman 2003
5	Copyright (C) GuoJunBo guojunbo@ict.ac.cn 2003
6
7	This program is free software; you can redistribute it and/or modify
8	it under the terms of the GNU General Public License as published by
9	the Free Software Foundation; either version 2 of the License, or
10	(at your option) any later version.
11
12	This program is distributed in the hope that it will be useful,
13	but WITHOUT ANY WARRANTY; without even the implied warranty of
14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15	GNU General Public License for more details.
16
17	You should have received a copy of the GNU General Public License
18	along with this program; if not, write to the Free Software
19	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20	*/
21
22	#include "rdesktop.h"
23	#include "rdpsnd.h"
24	#include "rdpsnd_dsp.h"
25
26	#define RDPSND_CLOSE 1
27	#define RDPSND_WRITE 2
28	#define RDPSND_SET_VOLUME 3
29	#define RDPSND_UNKNOWN4 4
30	#define RDPSND_COMPLETION 5
31	#define RDPSND_SERVERTICK 6
32	#define RDPSND_NEGOTIATE 7
33
34	#define MAX_FORMATS 10
35	#define MAX_QUEUE 10
36
37	BOOL g_dsp_busy = False;
38	int g_dsp_fd;
39
40	static VCHANNEL *rdpsnd_channel;
41	static struct audio_driver *drivers = NULL;
42	struct audio_driver *current_driver = NULL;
43
44	static BOOL device_open;
45	static WAVEFORMATEX formats[MAX_FORMATS];
46	static unsigned int format_count;
47	static unsigned int current_format;
48	unsigned int queue_hi, queue_lo;
49	struct audio_packet packet_queue[MAX_QUEUE];
50
51	void (*wave_out_play) (void);
52
53	static STREAM
54	rdpsnd_init_packet(uint16 type, uint16 size)
55	{
56	STREAM s;
57
58	s = channel_init(rdpsnd_channel, size + 4);
59	out_uint16_le(s, type);
60	out_uint16_le(s, size);
61	return s;
62	}
63
64	static void
65	rdpsnd_send(STREAM s)
66	{
67	#ifdef RDPSND_DEBUG
68	printf("RDPSND send:\n");
69	hexdump(s->channel_hdr + 8, s->end - s->channel_hdr - 8);
70	#endif
71
72	channel_send(s, rdpsnd_channel);
73	}
74
75	void
76	rdpsnd_send_completion(uint16 tick, uint8 packet_index)
77	{
78	STREAM s;
79
80	s = rdpsnd_init_packet(RDPSND_COMPLETION, 4);
81	out_uint16_le(s, tick);
82	out_uint8(s, packet_index);
83	out_uint8(s, 0);
84	s_mark_end(s);
85	rdpsnd_send(s);
86	}
87
88	static void
89	rdpsnd_process_negotiate(STREAM in)
90	{
91	unsigned int in_format_count, i;
92	WAVEFORMATEX *format;
93	STREAM out;
94	BOOL device_available = False;
95	int readcnt;
96	int discardcnt;
97
98	in_uint8s(in, 14); /* flags, volume, pitch, UDP port */
99	in_uint16_le(in, in_format_count);
100	in_uint8s(in, 4); /* pad, status, pad */
101
102	if (current_driver->wave_out_open())
103	{
104	current_driver->wave_out_close();
105	device_available = True;
106	}
107
108	format_count = 0;
109	if (s_check_rem(in, 18 * in_format_count))
110	{
111	for (i = 0; i < in_format_count; i++)
112	{
113	format = &formats[format_count];
114	in_uint16_le(in, format->wFormatTag);
115	in_uint16_le(in, format->nChannels);
116	in_uint32_le(in, format->nSamplesPerSec);
117	in_uint32_le(in, format->nAvgBytesPerSec);
118	in_uint16_le(in, format->nBlockAlign);
119	in_uint16_le(in, format->wBitsPerSample);
120	in_uint16_le(in, format->cbSize);
121
122	/* read in the buffer of unknown use */
123	readcnt = format->cbSize;
124	discardcnt = 0;
125	if (format->cbSize > MAX_CBSIZE)
126	{
127	fprintf(stderr, "cbSize too large for buffer: %d\n",
128	format->cbSize);
129	readcnt = MAX_CBSIZE;
130	discardcnt = format->cbSize - MAX_CBSIZE;
131	}
132	in_uint8a(in, format->cb, readcnt);
133	in_uint8s(in, discardcnt);
134
135	if (device_available && current_driver->wave_out_format_supported(format))
136	{
137	format_count++;
138	if (format_count == MAX_FORMATS)
139	break;
140	}
141	}
142	}
143
144	out = rdpsnd_init_packet(RDPSND_NEGOTIATE \| 0x200, 20 + 18 * format_count);
145	out_uint32_le(out, 3); /* flags */
146	out_uint32(out, 0xffffffff); /* volume */
147	out_uint32(out, 0); /* pitch */
148	out_uint16(out, 0); /* UDP port */
149
150	out_uint16_le(out, format_count);
151	out_uint8(out, 0x95); /* pad? */
152	out_uint16_le(out, 2); /* status */
153	out_uint8(out, 0x77); /* pad? */
154
155	for (i = 0; i < format_count; i++)
156	{
157	format = &formats[i];
158	out_uint16_le(out, format->wFormatTag);
159	out_uint16_le(out, format->nChannels);
160	out_uint32_le(out, format->nSamplesPerSec);
161	out_uint32_le(out, format->nAvgBytesPerSec);
162	out_uint16_le(out, format->nBlockAlign);
163	out_uint16_le(out, format->wBitsPerSample);
164	out_uint16(out, 0); /* cbSize */
165	}
166
167	s_mark_end(out);
168	rdpsnd_send(out);
169	}
170
171	static void
172	rdpsnd_process_servertick(STREAM in)
173	{
174	uint16 tick1, tick2;
175	STREAM out;
176
177	/* in_uint8s(in, 4); unknown */
178	in_uint16_le(in, tick1);
179	in_uint16_le(in, tick2);
180
181	out = rdpsnd_init_packet(RDPSND_SERVERTICK \| 0x2300, 4);
182	out_uint16_le(out, tick1);
183	out_uint16_le(out, tick2);
184	s_mark_end(out);
185	rdpsnd_send(out);
186	}
187
188	static void
189	rdpsnd_process(STREAM s)
190	{
191	uint8 type;
192	uint16 datalen;
193	uint32 volume;
194	static uint16 tick, format;
195	static uint8 packet_index;
196	static BOOL awaiting_data_packet;
197
198	#ifdef RDPSND_DEBUG
199	printf("RDPSND recv:\n");
200	hexdump(s->p, s->end - s->p);
201	#endif
202
203	if (awaiting_data_packet)
204	{
205	if (format >= MAX_FORMATS)
206	{
207	error("RDPSND: Invalid format index\n");
208	return;
209	}
210
211	if (!device_open \|\| (format != current_format))
212	{
213	if (!device_open && !current_driver->wave_out_open())
214	{
215	rdpsnd_send_completion(tick, packet_index);
216	return;
217	}
218	if (!current_driver->wave_out_set_format(&formats[format]))
219	{
220	rdpsnd_send_completion(tick, packet_index);
221	current_driver->wave_out_close();
222	device_open = False;
223	return;
224	}
225	device_open = True;
226	current_format = format;
227	}
228
229	current_driver->
230	wave_out_write(rdpsnd_dsp_process
231	(s, current_driver, &formats[current_format]), tick,
232	packet_index);
233	awaiting_data_packet = False;
234	return;
235	}
236
237	in_uint8(s, type);
238	in_uint8s(s, 1); /* unknown? */
239	in_uint16_le(s, datalen);
240
241	switch (type)
242	{
243	case RDPSND_WRITE:
244	in_uint16_le(s, tick);
245	in_uint16_le(s, format);
246	in_uint8(s, packet_index);
247	awaiting_data_packet = True;
248	break;
249	case RDPSND_CLOSE:
250	current_driver->wave_out_close();
251	device_open = False;
252	break;
253	case RDPSND_NEGOTIATE:
254	rdpsnd_process_negotiate(s);
255	break;
256	case RDPSND_SERVERTICK:
257	rdpsnd_process_servertick(s);
258	break;
259	case RDPSND_SET_VOLUME:
260	in_uint32(s, volume);
261	if (device_open)
262	{
263	current_driver->wave_out_volume((volume & 0xffff),
264	(volume & 0xffff0000) >> 16);
265	}
266	break;
267	default:
268	unimpl("RDPSND packet type %d\n", type);
269	break;
270	}
271	}
272
273	BOOL
274	rdpsnd_init(void)
275	{
276	rdpsnd_channel =
277	channel_register("rdpsnd", CHANNEL_OPTION_INITIALIZED \| CHANNEL_OPTION_ENCRYPT_RDP,
278	rdpsnd_process);
279
280	return (rdpsnd_channel != NULL);
281	}
282
283	BOOL
284	rdpsnd_auto_open(void)
285	{
286	current_driver = drivers;
287	while (current_driver != NULL)
288	{
289	DEBUG(("trying %s...\n", current_driver->name));
290	if (current_driver->wave_out_open())
291	{
292	DEBUG(("selected %s\n", current_driver->name));
293	return True;
294	}
295	g_dsp_fd = 0;
296	current_driver = current_driver->next;
297	}
298
299	warning("no working audio-driver found\n");
300
301	return False;
302	}
303
304	void
305	rdpsnd_register_drivers(char *options)
306	{
307	struct audio_driver **reg;
308
309	/* The order of registrations define the probe-order
310	when opening the device for the first time */
311	reg = &drivers;
312	#if defined(RDPSND_ALSA)
313	*reg = alsa_register(options);
314	reg = &((*reg)->next);
315	#endif
316	#if defined(RDPSND_OSS)
317	*reg = oss_register(options);
318	reg = &((*reg)->next);
319	#endif
320	#if defined(RDPSND_SUN)
321	*reg = sun_register(options);
322	reg = &((*reg)->next);
323	#endif
324	#if defined(RDPSND_SGI)
325	*reg = sgi_register(options);
326	reg = &((*reg)->next);
327	#endif
328	#if defined(RDPSND_LIBAO)
329	*reg = libao_register(options);
330	reg = &((*reg)->next);
331	#endif
332	}
333
334	BOOL
335	rdpsnd_select_driver(char driver, char options)
336	{
337	static struct audio_driver auto_driver;
338	struct audio_driver *pos;
339
340	drivers = NULL;
341	rdpsnd_register_drivers(options);
342
343	if (!driver)
344	{
345	auto_driver.wave_out_open = &rdpsnd_auto_open;
346	current_driver = &auto_driver;
347	return True;
348	}
349
350	pos = drivers;
351	while (pos != NULL)
352	{
353	if (!strcmp(pos->name, driver))
354	{
355	DEBUG(("selected %s\n", pos->name));
356	current_driver = pos;
357	return True;
358	}
359	pos = pos->next;
360	}
361	return False;
362	}
363
364	void
365	rdpsnd_show_help(void)
366	{
367	struct audio_driver *pos;
368
369	rdpsnd_register_drivers(NULL);
370
371	pos = drivers;
372	while (pos != NULL)
373	{
374	fprintf(stderr, " %s:\t%s\n", pos->name, pos->description);
375	pos = pos->next;
376	}
377	}
378
379	inline void
380	rdpsnd_play(void)
381	{
382	current_driver->wave_out_play();
383	}
384
385	void
386	rdpsnd_queue_write(STREAM s, uint16 tick, uint8 index)
387	{
388	struct audio_packet *packet = &packet_queue[queue_hi];
389	unsigned int next_hi = (queue_hi + 1) % MAX_QUEUE;
390
391	if (next_hi == queue_lo)
392	{
393	error("No space to queue audio packet\n");
394	return;
395	}
396
397	queue_hi = next_hi;
398
399	packet->s = *s;
400	packet->tick = tick;
401	packet->index = index;
402
403	if (!g_dsp_busy)
404	current_driver->wave_out_play();
405	}
406
407	inline struct audio_packet *
408	rdpsnd_queue_current_packet(void)
409	{
410	return &packet_queue[queue_lo];
411	}
412
413	inline BOOL
414	rdpsnd_queue_empty(void)
415	{
416	return (queue_lo == queue_hi);
417	}
418
419	inline void
420	rdpsnd_queue_init(void)
421	{
422	queue_lo = queue_hi = 0;
423	}
424
425	inline void
426	rdpsnd_queue_next(void)
427	{
428	xfree(packet_queue[queue_lo].s.data);
429	queue_lo = (queue_lo + 1) % MAX_QUEUE;
430	}
431
432	inline int
433	rdpsnd_queue_next_tick(void)
434	{
435	if (((queue_lo + 1) % MAX_QUEUE) != queue_hi)
436	{
437	return packet_queue[(queue_lo + 1) % MAX_QUEUE].tick;
438	}
439	else
440	{
441	return (packet_queue[queue_lo].tick + 65535) % 65536;
442	}
443	}