summaryrefslogtreecommitdiff
path: root/driver_garmin.c
blob: ba39d5971873b3ee78629a229e43de8ca0110571 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
/*
 * This file contains two drivers for Garmin receivers and some code
 * shared by both drivers.
 *
 * One driver "garmin_usb_binary" handles the Garmin binary packet
 * format supported by the USB Garmins tested with the Garmin 18 and
 * other models.  (There is also "garmin_usb_binary_old".)  These are ONLY
 * for USB devices reporting as: 091e:0003.
 *
 * The other driver "garmin_ser_binary" is for Garmin receivers via a
 * serial port, whether or not one uses a USB/serial adaptor or a real
 * serial port.  These receivers provide adequate NMEA support, so it
 * often makes sense to just put them into NMEA mode.
 *
 * On Linux, USB Garmins (091e:0003) need the Linux garmin_gps driver and
 * will not function without it.  On other operating systems, it is clear
 * garmin_usb_binary_old does not work since it requires the Linux
 * garmin_gps module.
 *
 * This code has been tested and at least at one time is known to work on
 * big- and little-endian CPUs and 32 and 64 bit cpu modes.
 *
 *
 * Documentation for the Garmin protocols can be found via
 *   http://www.garmin.com/support/commProtocol.html
 * The file IOSDK.zip contains IntfSpec.pdf, which describes the
 * protocol in terms of Application, Link, and Physical.  This
 * identical file is also available at:
 *   http://www.garmin.com/support/pdf/iop_spec.pdf
 * An older version of iop_spec.pdf that describes only Serial Binary
 * is available at:
 *   http://vancouver-webpages.com/pub/peter/iop_spec.pdf
 * Information about the GPS 18
 *   http://www.garmin.com/manuals/425_TechnicalSpecification.pdf
 *
 * There is one physical link protocol for serial which uses DLE/ETX
 * framing.  There is another physical protocol for USB which relies
 * on the packetization intrinstic to USB bulk pipes.
 *
 * There are several link protocols; all devices implement L000.
 * There are then product-specific protocols; most devices implement
 * L001.  Link protocols are the same and carried over either Physical
 * protocol.
 *
 * Application protocols are named A000 and then with different
 * 3-digit numbres.  They are carried over Link protocols.
 *
 * Thus, much of the higher-level code dealing the data formats is
 * shared between USB Binary and Serial Binary.
 *
 * This code is partly from the Garmin IOSDK and partly from the
 * sample code in the Linux garmin_gps driver.
 *
 * bad code by: Gary E. Miller <gem@rellim.com>
 *
 * -D 3 = packet trace
 * -D 4 = packet details
 * -D 5 = more packet details
 * -D 6 = very excessive details
 *
 * limitations:
 *
 * do not have from garmin:
 *      pdop
 *      hdop
 *      vdop
 *	magnetic variation
 *
 * known bugs:
 *      hangs in the fread loop instead of keeping state and returning.
 *
 * TODO:
 *
 *	?? Add probe function for Serial Binary to start PVT output.
 *
 * This file is Copyright (c) 2010 by the GPSD project
 * BSD terms apply: see the file COPYING in the distribution root for details.
 */

#define __USE_POSIX199309 1

#include <stdio.h>
#include <stdbool.h>
#include <math.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#ifndef S_SPLINT_S
#include <unistd.h>
#endif /* S_SPLINT_S */

#include "gpsd_config.h"

#if defined(HAVE_LIBUSB)
#include <libusb.h>
#endif

#include "gpsd.h"
#include "bits.h"

#define GPSD_LE16TOH(x) getles16((char *)(&(x)), 0)
#define GPSD_LE32TOH(x) getles32((char *)(&(x)), 0)

#ifdef GARMIN_ENABLE

#define USE_RMD 0

/* Used in Serial Physical Layer */
#define ETX 0x03
#define ACK 0x06
#define DLE 0x10
#define NAK 0x15

#define GARMIN_LAYERID_TRANSPORT (uint8_t)  0
#define GARMIN_LAYERID_APPL      (uint32_t) 20
// Linux Garmin USB driver layer-id to use for some control mechanisms
#define GARMIN_LAYERID_PRIVATE  0x01106E4B

// packet ids used in private layer
#define PRIV_PKTID_SET_DEBUG    1
#define PRIV_PKTID_SET_MODE     2
#define PRIV_PKTID_INFO_REQ     3
#define PRIV_PKTID_INFO_RESP    4
#define PRIV_PKTID_RESET_REQ    5
#define PRIV_PKTID_SET_DEF_MODE 6

#define MODE_NATIVE	  0
#define MODE_GARMIN_SERIAL   1

#define GARMIN_PKTID_TRANSPORT_START_SESSION_REQ 5
#define GARMIN_PKTID_TRANSPORT_START_SESSION_RESP 6

#define GARMIN_PKTID_PROTOCOL_ARRAY     253
#define GARMIN_PKTID_PRODUCT_RQST       254
#define GARMIN_PKTID_PRODUCT_DATA       255
/* 0x29 ')' */
#define GARMIN_PKTID_RMD41_DATA	 41
/* 0x33 '3' */
#define GARMIN_PKTID_PVT_DATA	   51
/* 0x33 '4' */
#define GARMIN_PKTID_RMD_DATA	   52
/* 0x72 'r' */
#define GARMIN_PKTID_SAT_DATA	   114

#define GARMIN_PKTID_L001_XFER_CMPLT     12
#define GARMIN_PKTID_L001_COMMAND_DATA   10
#define GARMIN_PKTID_L001_DATE_TIME_DATA 14
#define GARMIN_PKTID_L001_RECORDS	27
#define GARMIN_PKTID_L001_WPT_DATA       35

#define	CMND_ABORT			 0
#define	CMND_START_PVT_DATA		 49
#define	CMND_STOP_PVT_DATA		 50
#define	CMND_START_RM_DATA		 110

#define MAX_BUFFER_SIZE 4096

#define GARMIN_CHANNELS	12

// something magic about 64, garmin driver will not return more than
// 64 at a time.  If you read less than 64 bytes the next read will
// just get the last of the 64 byte buffer.
#define ASYNC_DATA_SIZE 64


#pragma pack(1)
// This is the data format of the satellite data from the garmin USB
typedef struct
{
    uint8_t svid;
    uint16_t snr;		// 0 - 0xffff
    uint8_t elev;
    uint16_t azmth;
    uint8_t status;		// bit 0, has ephemeris, 1, has diff correction
    // bit 2 used in solution
    // bit 3??
} cpo_sat_data;

/* Garmin D800_Pvt_Datetype_Type */
/* packet type:  GARMIN_PKTID_PVT_DATA   52 */
/* This is the data format of the position data from the garmin USB */
typedef struct
{
    float alt;			/* altitude above WGS 84 (meters) */
    float epe;			/* estimated position error, 2 sigma (meters)  */
    float eph;			/* epe, but horizontal only (meters) */
    float epv;			/* epe but vertical only (meters ) */
    int16_t fix;		/* 0 - failed integrity check
				 * 1 - invalid or unavailable fix
				 * 2 - 2D
				 * 3 - 3D
				 * 4 - 2D Diff
				 * 5 - 3D Diff
				 */
    double gps_tow;		/* gps time of week (seconds) */
    double lat;			/* ->latitude (radians) */
    double lon;			/* ->longitude (radians) */
    float lon_vel;		/* velocity east (meters/second) */
    float lat_vel;		/* velocity north (meters/second) */
    float alt_vel;		/* velocity up (meters/sec) */
    // Garmin GPS25 uses pkt_id 0x28 and does not output the
    // next 3 items
    float msl_hght;		/* height of WGS 84 above MSL (meters) */
    int16_t leap_sec;		/* diff between GPS and UTC (seconds) */
    int32_t grmn_days;		/* days from UTC December 31st, 1989 to the
				 * beginning of the current week */
} cpo_pvt_data;

typedef struct
{
    uint32_t cycles;
    double pr;
    uint16_t phase;
    int8_t slp_dtct;
    uint8_t snr_dbhz;
    uint8_t svid;
    int8_t valid;
} cpo_rcv_sv_data;

/* packet type:  GARMIN_PKTID_RMD_DATA   53 */
/* seems identical to the packet id 0x29 from the Garmin GPS 25 */
typedef struct
{
    double rcvr_tow;
    int16_t rcvr_wn;
    cpo_rcv_sv_data sv[GARMIN_CHANNELS];
} cpo_rcv_data;

// This is the packet format to/from the Garmin USB
typedef struct
{
    uint8_t mPacketType;
    uint8_t mReserved1;
    uint16_t mReserved2;
    uint16_t mPacketId;
    uint16_t mReserved3;
    uint32_t mDataSize;
    union
    {
	int8_t chars[MAX_BUFFER_SIZE];
	uint8_t uchars[MAX_BUFFER_SIZE];
	cpo_pvt_data pvt;
	cpo_sat_data sats;
    } mData;
} Packet_t;

// useful funcs to read/write ints
//  floats and doubles are Intel (little-endian) order only...
static inline void set_int16(uint8_t * buf, uint32_t value)
{
    buf[0] = (uint8_t) (0x0FF & value);
    buf[1] = (uint8_t) (0x0FF & (value >> 8));
}

static inline void set_int32(uint8_t * buf, uint32_t value)
{
    buf[0] = (uint8_t) (0x0FF & value);
    buf[1] = (uint8_t) (0x0FF & (value >> 8));
    buf[2] = (uint8_t) (0x0FF & (value >> 16));
    buf[3] = (uint8_t) (0x0FF & (value >> 24));
}

static inline uint16_t get_uint16(const uint8_t * buf)
{
    return (uint16_t) (0xFF & buf[0])
	| ((uint16_t) (0xFF & buf[1]) << 8);
}

static inline uint32_t get_int32(const uint8_t * buf)
{
    return (uint32_t) (0xFF & buf[0])
	| ((uint32_t) (0xFF & buf[1]) << 8)
	| ((uint32_t) (0xFF & buf[2]) << 16)
	| ((uint32_t) (0xFF & buf[3]) << 24);
}

// convert radians to degrees
static inline double radtodeg(double rad)
{
    return (double)(rad * RAD_2_DEG);
}

static gps_mask_t PrintSERPacket(struct gps_device_t *session,
				 unsigned char pkt_id, int pkt_len,
				 unsigned char *buf);
static gps_mask_t PrintUSBPacket(struct gps_device_t *session,
				 Packet_t * pkt);

gps_mask_t PrintSERPacket(struct gps_device_t *session, unsigned char pkt_id,
			  int pkt_len, unsigned char *buf)
{

    gps_mask_t mask = 0;
    int i = 0, j = 0;
    uint16_t prod_id = 0;
    uint16_t ver = 0;
    int maj_ver;
    int min_ver;
    time_t time_l = 0;
    double track;
    char msg_buf[512] = "";
    char *msg = NULL;
    cpo_sat_data *sats = NULL;
    cpo_pvt_data *pvt = NULL;
    cpo_rcv_data *rmd = NULL;

    gpsd_report(LOG_IO, "Garmin: PrintSERPacket(, %#02x, %#02x, )\n", pkt_id,
		pkt_len);

    session->cycle_end_reliable = true;

    switch (pkt_id) {
    case ACK:
	gpsd_report(LOG_PROG, "Garmin: ACK\n");
	break;
    case NAK:
	gpsd_report(LOG_PROG, "Garmin: NAK\n");
	break;
    case GARMIN_PKTID_L001_COMMAND_DATA:
	prod_id = get_uint16((uint8_t *) buf);
	/*@ -branchstate @*/
	switch (prod_id) {
	case CMND_ABORT:
	    msg = "Abort current xfer";
	    break;
	case CMND_START_PVT_DATA:
	    msg = "Start Xmit PVT data";
	    break;
	case CMND_STOP_PVT_DATA:
	    msg = "Stop Xmit PVT data";
	    break;
	case CMND_START_RM_DATA:
	    msg = "Start RMD data";
	    break;
	default:
	    (void)snprintf(msg_buf, sizeof(msg_buf), "Unknown: %u",
			   (unsigned int)prod_id);
	    msg = msg_buf;
	    break;
	}
	/*@ +branchstate @*/
	gpsd_report(LOG_PROG, "Garmin: Appl, Command Data: %s\n", msg);
	break;
    case GARMIN_PKTID_PRODUCT_RQST:
	gpsd_report(LOG_PROG, "Garmin: Appl, Product Data req\n");
	break;
    case GARMIN_PKTID_PRODUCT_DATA:
	prod_id = get_uint16((uint8_t *) buf);
	ver = get_uint16((uint8_t *) & buf[2]);
	maj_ver = (int)(ver / 100);
	min_ver = (int)(ver - (maj_ver * 100));
	gpsd_report(LOG_PROG, "Garmin: Appl, Product Data, sz: %d\n",
		    pkt_len);
	(void)snprintf(session->subtype, sizeof(session->subtype),
		       "%d: %d.%02d", (int)prod_id, maj_ver, min_ver);
	gpsd_report(LOG_INF, "Garmin: Product ID: %d, SoftVer: %d.%02d\n",
		    prod_id, maj_ver, min_ver);
	gpsd_report(LOG_INF, "Garmin: Product Desc: %s\n", &buf[4]);
	mask |= DEVICEID_SET;
	gpsd_report(LOG_DATA, "Garmin: PRODUCT_DATA: subtype=%s\n",
		    session->subtype);
	break;
    case GARMIN_PKTID_PVT_DATA:
	gpsd_report(LOG_PROG, "Garmin: Appl, PVT Data Sz: %d\n", pkt_len);

	pvt = (cpo_pvt_data *) buf;

	// 631065600, unix seconds for 31 Dec 1989 Zulu
	time_l = (time_t) (631065600 + (GPSD_LE32TOH(pvt->grmn_days) * 86400));
	// TODO, convert grmn_days to context->gps_week
	time_l -= GPSD_LE16TOH(pvt->leap_sec);
	session->context->leap_seconds = (int)GPSD_LE16TOH(pvt->leap_sec);
	session->context->valid = LEAP_SECOND_VALID;
	// gps_tow is always like x.999 or x.998 so just round it
	time_l += (time_t) round(pvt->gps_tow);
	session->context->gps_tow = pvt->gps_tow;
	session->newdata.time = (timestamp_t)time_l;
	gpsd_report(LOG_PROG, "Garmin: time_l: %ld\n", (long int)time_l);

	session->newdata.latitude = radtodeg(pvt->lat);
	/* sanity check the lat */
	if (90.0 < session->newdata.latitude) {
	    session->newdata.latitude = 90.0;
	    gpsd_report(LOG_INF, "Garmin: ERROR: Latitude overrange\n");
	} else if (-90.0 > session->newdata.latitude) {
	    session->newdata.latitude = -90.0;
	    gpsd_report(LOG_INF,
			"Garmin: ERROR: Latitude negative overrange\n");
	}
	session->newdata.longitude = radtodeg(pvt->lon);
	/* sanity check the lon */
	if (180.0 < session->newdata.longitude) {
	    session->newdata.longitude = 180.0;
	    gpsd_report(LOG_INF, "Garmin: ERROR: Longitude overrange\n");
	} else if (-180.0 > session->newdata.longitude) {
	    session->newdata.longitude = -180.0;
	    gpsd_report(LOG_INF,
			"Garmin: ERROR: Longitude negative overrange\n");
	}
	// altitude over WGS84 converted to MSL
	session->newdata.altitude = pvt->alt + pvt->msl_hght;

	// geoid separation from WGS 84
	// gpsd sign is opposite of garmin sign
	session->gpsdata.separation = -pvt->msl_hght;

	// Estimated position error in meters.
	// We follow the advice at <http://gpsinformation.net/main/errors.htm>.
	// If this assumption changes here, it should also change in
	// nmea_parse.c where we analyze PGRME.
	session->gpsdata.epe = pvt->epe * (GPSD_CONFIDENCE / CEP50_SIGMA);
	/* eph is a circular error, sqrt(epx**2 + epy**2) */
	session->newdata.epx = session->newdata.epy =
	    pvt->eph * (1 / sqrt(2)) * (GPSD_CONFIDENCE / CEP50_SIGMA);
	session->newdata.epv = pvt->epv * (GPSD_CONFIDENCE / CEP50_SIGMA);

	// convert lat/lon to directionless speed
	session->newdata.speed = hypot(pvt->lon_vel, pvt->lat_vel);

	// keep climb in meters/sec
	session->newdata.climb = pvt->alt_vel;

	track = atan2(pvt->lon_vel, pvt->lat_vel);
	if (track < 0) {
	    track += 2 * GPS_PI;
	}
	session->newdata.track = radtodeg(track);

	switch (GPSD_LE16TOH(pvt->fix)) {
	case 0:
	case 1:
	default:
	    // no fix
	    session->gpsdata.status = STATUS_NO_FIX;
	    session->newdata.mode = MODE_NO_FIX;
	    break;
	case 2:
	    // 2D fix
	    session->gpsdata.status = STATUS_FIX;
	    session->newdata.mode = MODE_2D;
	    break;
	case 3:
	    // 3D fix
	    session->gpsdata.status = STATUS_FIX;
	    session->newdata.mode = MODE_3D;
	    break;
	case 4:
	    // 2D Differential fix
	    session->gpsdata.status = STATUS_DGPS_FIX;
	    session->newdata.mode = MODE_2D;
	    break;
	case 5:
	    // 3D differential fix
	    session->gpsdata.status = STATUS_DGPS_FIX;
	    session->newdata.mode = MODE_3D;
	    break;
	}

	gpsd_report(LOG_PROG, "Garmin: Appl, mode %d, status %d\n",
		    session->newdata.mode, session->gpsdata.status);

	gpsd_report(LOG_INF, "Garmin: UTC Time: %lf\n",
		    session->newdata.time);
	gpsd_report(LOG_INF,
		    "Garmin: Geoid Separation (MSL-WGS84): from garmin %lf, calculated %lf\n",
		    -pvt->msl_hght,
		    wgs84_separation(session->newdata.latitude,
				     session->newdata.longitude));

	gpsd_report(LOG_INF,
		    "Garmin: Alt: %.3f, Epe: %.3f, Eph: %.3f, Epv: %.3f, Fix: %d, Gps_tow: %f, Lat: %.3f, Lon: %.3f, LonVel: %.3f, LatVel: %.3f, AltVel: %.3f, MslHgt: %.3f, Leap: %d, GarminDays: %d\n",
		    pvt->alt, pvt->epe, pvt->eph, pvt->epv, GPSD_LE16TOH(pvt->fix),
		    pvt->gps_tow, session->newdata.latitude,
		    session->newdata.longitude, pvt->lon_vel, pvt->lat_vel,
		    pvt->alt_vel, pvt->msl_hght, GPSD_LE16TOH(pvt->leap_sec),
		    GPSD_LE32TOH(pvt->grmn_days));

	if (session->newdata.mode > MODE_NO_FIX) {
	    /* data only valid with a fix */
	    mask |=
		TIME_SET | LATLON_SET | ALTITUDE_SET | STATUS_SET | MODE_SET |
		SPEED_SET | TRACK_SET | CLIMB_SET | HERR_SET | VERR_SET | PERR_IS |
		CLEAR_IS | REPORT_IS;
	    /*
	     * Garmin documentation says we should wait until four good fixes
	     * have been seen before trying to use the device for precision 
	     * time service.
	     */
	    if (session->fixcnt > 3)
		mask |= PPSTIME_IS;
	}
	gpsd_report(LOG_DATA,
		    "Garmin: PVT_DATA: time=%.2f, lat=%.2f lon=%.2f "
		    "speed=%.2f track=%.2f climb=%.2f "
		    "epx=%.2f epy=%.2f epv=%.2f "
		    "mode=%d status=%d\n",
		    session->newdata.time,
		    session->newdata.latitude,
		    session->newdata.longitude,
		    session->newdata.speed,
		    session->newdata.track,
		    session->newdata.climb,
		    session->newdata.epx,
		    session->newdata.epy,
		    session->newdata.epv,
		    session->newdata.mode,
		    session->gpsdata.status);
	break;
    case GARMIN_PKTID_RMD_DATA:
    case GARMIN_PKTID_RMD41_DATA:
	rmd = (cpo_rcv_data *) buf;
	gpsd_report(LOG_IO, "Garmin: PVT RMD Data Sz: %d\n", pkt_len);
	gpsd_report(LOG_PROG, "Garmin: PVT RMD rcvr_tow: %f, rcvr_wn: %d\n",
		    rmd->rcvr_tow, rmd->rcvr_wn);
	for (i = 0; i < GARMIN_CHANNELS; i++) {
	    gpsd_report(LOG_INF,
			"Garmin: PVT RMD Sat: %3u, cycles: %9u, pr: %16.6f, "
			"phase: %7.3f, slp_dtct: %3s, snr: %3u, Valid: %3s\n",
			(int)rmd->sv[i].svid + 1, 
			GPSD_LE32TOH(rmd->sv[i].cycles), 
			rmd->sv[i].pr,
			(GPSD_LE16TOH(rmd->sv[i].phase) * 360.0) / 2048.0,
			rmd->sv[i].slp_dtct != 0 ? "Yes" : "No",
			rmd->sv[i].snr_dbhz,
			rmd->sv[i].valid != 0 ? "Yes" : "No");
	}
	break;

    case GARMIN_PKTID_SAT_DATA:
	gpsd_report(LOG_PROG, "Garmin: SAT Data Sz: %d\n", pkt_len);
	sats = (cpo_sat_data *) buf;

	session->gpsdata.satellites_visible = 0;
	session->gpsdata.satellites_used = 0;
	memset(session->gpsdata.used, 0, sizeof(session->gpsdata.used));
	gpsd_zero_satellites(&session->gpsdata);
	for (i = 0, j = 0; i < GARMIN_CHANNELS; i++, sats++) {
	    gpsd_report(LOG_INF,
			"Garmin:   Sat %3d, snr: %5u, elev: %2d, Azmth: %3d, Stat: %x\n",
			sats->svid, GPSD_LE16TOH(sats->snr), sats->elev, 
			GPSD_LE16TOH(sats->azmth),
			sats->status);

	    if (255 == (int)sats->svid) {
		// Garmin uses 255 for empty
		// gpsd uses 0 for empty
		continue;
	    }

	    if ((int)sats->svid <= 32)
		session->gpsdata.PRN[j] = (int)sats->svid;	/* GPS */
	    else
		session->gpsdata.PRN[j] = (int)sats->svid + 87;	/* SBAS */
	    session->gpsdata.azimuth[j] = (int)GPSD_LE16TOH(sats->azmth);
	    session->gpsdata.elevation[j] = (int)sats->elev;
	    // Garmin does not document this.  snr is in dB*100
	    // Known, but not seen satellites have a dB value of -1*100
	    session->gpsdata.ss[j] = (float)(GPSD_LE16TOH(sats->snr) / 100.0);
	    if (session->gpsdata.ss[j] == -1) {
		continue;
	    }
	    // FIX-ME: Garmin documents this, but Daniel Dorau
	    // <daniel.dorau@gmx.de> says the behavior on his GPSMap60CSX
	    // doesn't match it.
	    if ((uint8_t) 0 != (sats->status & 4)) {
		// used in solution?
		session->gpsdata.used[session->gpsdata.satellites_used++]
		    = session->gpsdata.PRN[j];
	    }
	    session->gpsdata.satellites_visible++;
	    j++;

	}
	session->gpsdata.skyview_time = NAN;
	if (session->gpsdata.satellites_visible > 0)
	    mask |= SATELLITE_SET;
	if (session->gpsdata.satellites_used > 0)
	    mask |= USED_IS;
	gpsd_report(LOG_DATA,
		    "Garmin: SAT_DATA: visible=%d used=%d\n",
		    session->gpsdata.satellites_visible,
		    session->gpsdata.satellites_used);
	break;
    case GARMIN_PKTID_PROTOCOL_ARRAY:
	// this packet is never requested, it just comes, in some case
	// after a GARMIN_PKTID_PRODUCT_RQST
	gpsd_report(LOG_INF, "Garmin: Appl, Product Capability, sz: %d\n",
		    pkt_len);
	for (i = 0; i < pkt_len; i += 3) {
	    gpsd_report(LOG_INF, "Garmin:   %c%03d\n", buf[i],
			get_uint16((uint8_t *) & buf[i + 1]));
	}
	break;
    default:
	gpsd_report(LOG_WARN,
		    "Garmin: Unknown packet id: %#02x, Sz: %#02x\n",
		    pkt_id, pkt_len);
	break;
    }
    gpsd_report(LOG_IO, "Garmin: PrintSERPacket(, %#02x, %#02x, )\n",
		pkt_id, pkt_len);
    return mask;
}


/*@ -branchstate @*/
// For debugging, decodes and prints some known packets.
static gps_mask_t PrintUSBPacket(struct gps_device_t *session, Packet_t * pkt)
{
    gps_mask_t mask = 0;
    int maj_ver;
    int min_ver;
    uint32_t mode = 0;
    uint16_t prod_id = 0;
    uint32_t veri = 0;
    uint32_t serial;
    uint32_t mDataSize = get_int32((uint8_t *) & pkt->mDataSize);

//
    uint8_t *buffer = (uint8_t *) pkt;

    gpsd_report(LOG_PROG, "Garmin: PrintUSBPacket()\n");
// gem
    if (DLE == pkt->mPacketType) {
	gpsd_report(LOG_PROG, "Garmin: really a SER packet!\n");
	return PrintSERPacket(session,
			      (unsigned char)buffer[1],
			      (int)buffer[2], (unsigned char *)(buffer + 3));
    }
// gem
    if (4096 < mDataSize) {
	gpsd_report(LOG_WARN, "Garmin: bogus packet, size too large=%d\n",
		    mDataSize);
	return 0;
    }

    (void)snprintf(session->gpsdata.tag, sizeof(session->gpsdata.tag), "%u",
		   (unsigned int)pkt->mPacketType);
    switch (pkt->mPacketType) {
    case GARMIN_LAYERID_TRANSPORT:
	/* Garmin USB layer specific */
	switch (pkt->mPacketId) {
	case GARMIN_PKTID_TRANSPORT_START_SESSION_REQ:
	    gpsd_report(LOG_PROG, "Garmin: Transport, Start Session req\n");
	    break;
	case GARMIN_PKTID_TRANSPORT_START_SESSION_RESP:
	    mode = get_int32(&pkt->mData.uchars[0]);
	    gpsd_report(LOG_PROG,
			"Garmin: Transport, Start Session resp, unit: 0x%x\n",
			mode);
	    break;
	default:
	    gpsd_report(LOG_PROG,
			"Garmin: Transport, Packet: Type %d %d %d, ID: %d, Sz: %d\n",
			pkt->mPacketType, pkt->mReserved1, pkt->mReserved2,
			pkt->mPacketId, mDataSize);
	    break;
	}
	break;
    case GARMIN_LAYERID_APPL:
	/* raw data transport, shared with Garmin Serial Driver */

	mask = PrintSERPacket(session,
			      (unsigned char)pkt->mPacketId,
			      (int)mDataSize,
			      (unsigned char *)pkt->mData.uchars);
	break;
    case 75:
	// private, garmin USB kernel driver specific
	switch (pkt->mPacketId) {
	case PRIV_PKTID_SET_MODE:
	    prod_id = get_uint16(&pkt->mData.uchars[0]);
	    gpsd_report(LOG_PROG, "Garmin: Private, Set Mode: %d\n", prod_id);
	    break;
	case PRIV_PKTID_INFO_REQ:
	    gpsd_report(LOG_PROG, "Garmin: Private, ID: Info Req\n");
	    break;
	case PRIV_PKTID_INFO_RESP:
	    veri = get_int32(pkt->mData.uchars);
	    maj_ver = (int)(veri >> 16);
	    min_ver = (int)(veri & 0xffff);
	    mode = get_int32(&pkt->mData.uchars[4]);
	    serial = get_int32(&pkt->mData.uchars[8]);
	    gpsd_report(LOG_PROG, "Garmin: Private, ID: Info Resp\n");
	    gpsd_report(LOG_INF,
			"Garmin: USB Driver found, Version %d.%d, Mode: %d, GPS Serial# %u\n",
			maj_ver, min_ver, mode, serial);
	    break;
	default:
	    gpsd_report(LOG_PROG, "Garmin: Private, Packet: ID: %d, Sz: %d\n",
			pkt->mPacketId, mDataSize);
	    break;
	}
	break;
    default:
	gpsd_report(LOG_PROG,
		    "Garmin: Packet: Type %d %d %d, ID: %d, Sz: %d\n",
		    pkt->mPacketType, pkt->mReserved1, pkt->mReserved2,
		    pkt->mPacketId, mDataSize);
	break;
    }

    return mask;
}

/*@ +branchstate @*/


#if defined(__linux__) || defined(S_SPLINT_S)
/* build and send a packet w/ USB protocol */
static void Build_Send_USB_Packet(struct gps_device_t *session,
				  uint32_t layer_id, uint32_t pkt_id,
				  uint32_t length, uint32_t data)
{
    uint8_t *buffer = (uint8_t *) session->driver.garmin.Buffer;
    Packet_t *thePacket = (Packet_t *) buffer;
    ssize_t theBytesReturned = 0;
    ssize_t theBytesToWrite = 12 + (ssize_t) length;

    set_int32(buffer, layer_id);
    set_int32(buffer + 4, pkt_id);
    set_int32(buffer + 8, length);
    if (2 == length) {
	set_int16(buffer + 12, data);
    } else if (4 == length) {
	set_int32(buffer + 12, data);
    }
    (void)PrintUSBPacket(session, thePacket);

    theBytesReturned = gpsd_write(session, (const char *)thePacket,
				  (size_t) theBytesToWrite);
    gpsd_report(LOG_IO, "Garmin: SendPacket(), wrote %zd bytes\n",
		theBytesReturned);

    // Garmin says:
    // If the packet size was an exact multiple of the USB packet
    // size, we must make a final write call with no data

    // as a practical matter no known packets are 64 bytes long so
    // this is untested

    // So here goes just in case
    if (0 == (theBytesToWrite % ASYNC_DATA_SIZE)) {
	char *n = "";
	(void)gpsd_write(session, n, 0);
    }
}
#endif /* __linux__ || S_SPLINT_S */

/* build and send a packet in serial protocol */
/* layer_id unused */
// FIX-ME: This should go through the common message buffer someday
static void Build_Send_SER_Packet(struct gps_device_t *session,
				  uint32_t layer_id UNUSED, uint32_t pkt_id,
				  uint32_t length, uint32_t data)
{
    uint8_t *buffer = (uint8_t *) session->driver.garmin.Buffer;
    uint8_t *buffer0 = buffer;
    Packet_t *thePacket = (Packet_t *) buffer;
    ssize_t theBytesReturned = 0;
    ssize_t theBytesToWrite = 6 + (ssize_t) length;
    uint8_t chksum = 0;

    *buffer++ = (uint8_t) DLE;
    *buffer++ = (uint8_t) pkt_id;
    chksum = pkt_id;
    *buffer++ = (uint8_t) length;
    chksum += length;
    /* ??? What is this doing? */
    if (2 == length) {
	/* carefull!  no DLE stuffing here! */
	set_int16(buffer, data);
	chksum += buffer[0];
	chksum += buffer[1];
    } else if (4 == length) {
	/* carefull!  no DLE stuffing here! */
	set_int32(buffer, data);
	chksum += buffer[0];
	chksum += buffer[1];
	chksum += buffer[2];
	chksum += buffer[3];
    }
    /* ??? How is data copied to the buffer? */
    buffer += length;

    // Add checksum
    *buffer++ = -chksum;
    if (DLE == -chksum) {
	/* stuff another DLE */
	*buffer++ = (uint8_t) DLE;
	theBytesToWrite++;
    }
    // Add DLE, ETX
    *buffer++ = (uint8_t) DLE;
    /* we used to say n++ here, but scan-build complains */
    *buffer = (uint8_t) ETX;

    (void)PrintSERPacket(session,
			 (unsigned char)buffer0[1],
			 (int)buffer0[2], (unsigned char *)(buffer0 + 3));

    theBytesReturned = gpsd_write(session, (const char *)thePacket,
				  (size_t) theBytesToWrite);
    gpsd_report(LOG_IO, "Garmin: SendPacket(), wrote %zd bytes\n",
		theBytesReturned);

}

#if defined(HAVE_LIBUSB)
/*
 * is_usb_device() - is a specified device USB matching given vendor/product?
 *
 * BUG: Doesn't actually match against path yet. Must finish this function
 * by querying /sys/dev/char, either directly or using libudev. Greg KH
 * assures this is possible, though he is vague about how.
 *
 * libudev: http://www.kernel.org/pub/linux/utils/kernel/hotplug/libudev/
 */
/*@-compdef -usedef -nullpass@*/
static bool is_usb_device(const char *path UNUSED, int vendor, int product)
{
    // discover devices
    libusb_device **list;
    ssize_t cnt;
    ssize_t i = 0;
    bool found = false;

    gpsd_report(LOG_INF, "attempting USB device enumeration.\n");
    (void)libusb_init(NULL);

    if ((cnt = libusb_get_device_list(NULL, &list)) < 0) {
	gpsd_report(LOG_ERROR, "USB device list call failed.\n");
	libusb_exit(NULL);
	return false;
    }

    for (i = 0; i < cnt; i++) {
	struct libusb_device_descriptor desc;
	libusb_device *dev = list[i];

	int r = libusb_get_device_descriptor(dev, &desc);
	if (r < 0) {
	    gpsd_report(LOG_ERROR,
			"USB descriptor fetch failed on device %zd.\n", i);
	    continue;
	}

	/* we can extract device descriptor data */
	gpsd_report(LOG_INF, "%04x:%04x (bus %d, device %d)\n",
		    desc.idVendor, desc.idProduct,
		    libusb_get_bus_number(dev),
		    libusb_get_device_address(dev));

	/* we match if vendor and product ID are right */
	if (desc.idVendor == (uint16_t)vendor && desc.idProduct == (uint16_t)product) {
	    found = true;
	    break;
	}
    }

    gpsd_report(LOG_SHOUT, "vendor/product match with %04x:%04x %sfound\n",
		vendor, product, found ? "" : "not ");
    libusb_free_device_list(list, 1);
    libusb_exit(NULL);
    return found;
}

/*@-compdef -usedef -nullpass@*/
#endif /* HAVE_LIBUSB */

/*
 * garmin_usb_detect() - detect a Garmin USB device connected to session fd.
 *
 * This is ONLY for USB devices reporting as: 091e:0003.
 *
 * This driver ONLY works in Linux and ONLY when the garmin_gps kernel
 * module is installed.
 *
 * This is only necessary because under Linux Garmin USB devices need a
 * kernel module rather than being normal USB-serial devices.
 *
 * The actual wire protocol from the Garmin device is very strange. There
 * are no delimiters.  End of packet is signaled by a zero-length read
 * on the USB device, and start of packet is the next read.  You can't just
 * ignore the zero reads and pass the data through - you'd never be able
 * to tell where the packet boundaries are.
 *
 * The garmin_usb module's job is to grab the packet and frame it in
 * DLEs (with DLE stuffing).  This makes the USB packets look as
 * though they came from a regular Garmin *serial* device, which is how
 * most of the processing for both types can be unified here.
 *
 * return 1 is device found
 * return 0 if not
 */
static bool garmin_usb_detect(struct gps_device_t *session UNUSED)
{
#if defined(__linux__) || defined(S_SPLINT_S)
    /*
     * Only perform this check if we're looking at a USB-serial
     * device.  This prevents drivers for attached serial GPSes
     * fronm being rudely elbowed aside by this one if they happen
     * to be trying to coexist with the Garmin.
     */
    if (session->sourcetype != source_usb)
	return false;
    else {
#ifdef HAVE_LIBUSB
	if (!is_usb_device(session->gpsdata.dev.path, 0x091e, 0x0003))
	    return false;
#else
	return false;
#endif /* HAVE_LIBUSB */
	/*@-unreachable@*/
	if (!gpsd_set_raw(session)) {
	    gpsd_report(LOG_ERROR,
			"Garmin: garmin_usb_detect: error changing port attributes: %s\n",
			strerror(errno));
	    return false;
	}

	if (sizeof(session->driver.garmin.Buffer) < sizeof(Packet_t)) {
	    /* dunno how this happens, but it does on some compilers */
	    gpsd_report(LOG_ERROR,
			"Garmin: garmin_usb_detect: Compile error, garmin.Buffer too small.\n");
	    return false;
	}

	// FIXME!!! needs to use libusb totally and move garmin_gps aside */
	// set Mode 1, mode 0 is broken somewhere past 2.6.14
	// but how?
	gpsd_report(LOG_PROG, "Garmin: Set garmin_gps driver mode = 0\n");
	Build_Send_USB_Packet(session, GARMIN_LAYERID_PRIVATE,
			      PRIV_PKTID_SET_MODE, 4, MODE_GARMIN_SERIAL);
	// expect no return packet !?

	return true;
    }
#else
    return false;
#endif /* __linux__ || S_SPLINT_S */
}

static void garmin_event_hook(struct gps_device_t *session, event_t event)
{
    if (session->context->readonly)
	return;
    /*
     * FIX-ME: It might not be necessary to call this on reactivate.
     * Experiment to see if the holds its settings through a close.
     */
    if (event == event_identified || event == event_reactivate) {
	// Tell the device to send product data
	gpsd_report(LOG_PROG, "Garmin: Get Product Data\n");
	Build_Send_SER_Packet(session, GARMIN_LAYERID_APPL,
			      GARMIN_PKTID_PRODUCT_RQST, 0, 0);

	// turn on PVT data 49
	gpsd_report(LOG_PROG, "Garmin: Set to send reports every 1 second\n");

	Build_Send_SER_Packet(session, GARMIN_LAYERID_APPL,
			      GARMIN_PKTID_L001_COMMAND_DATA, 2,
			      CMND_START_PVT_DATA);

#if USE_RMD
	// turn on RMD data 110
	gpsd_report(LOG_PROG, "Garmin: Set to send Raw sat data\n");
	Build_Send_SER_Packet(session, GARMIN_LAYERID_APPL,
			      GARMIN_PKTID_L001_COMMAND_DATA, 2,
			      CMND_START_RM_DATA);
#endif
    }
    if (event == event_deactivate)
	/* FIX-ME: is any action needed, or is closing the port sufficient? */
	gpsd_report(LOG_PROG, "Garmin: garmin_close()\n");
}

#define Send_ACK()    Build_Send_SER_Packet(session, 0, ACK, 0, 0)
#define Send_NAK()    Build_Send_SER_Packet(session, 0, NAK, 0, 0)

/*@ +charint @*/
gps_mask_t garmin_ser_parse(struct gps_device_t *session)
{
    unsigned char *buf = session->packet.outbuffer;
    size_t len = session->packet.outbuflen;
    unsigned char data_buf[MAX_BUFFER_SIZE];
    unsigned char c;
    int i = 0;
    size_t n = 0;
    int data_index = 0;
    int got_dle = 0;
    unsigned char pkt_id = 0;
    unsigned char pkt_len = 0;
    unsigned char chksum = 0;
    gps_mask_t mask = 0;

    if (session->packet.type == GARMIN_PACKET)
	session->gpsdata.dev.driver_mode = MODE_BINARY;

    gpsd_report(LOG_RAW, "Garmin: garmin_ser_parse()\n");
    if (6 > len) {
	/* WTF? */
	/* minimum packet; <DLE> [pkt id] [length=0] [chksum] <DLE> <STX> */
	Send_NAK();
	gpsd_report(LOG_RAW + 1, "Garmin: serial too short: %zd\n", len);
	return 0;
    }
    /* debug */
    for (i = 0; i < (int)len; i++) {
	gpsd_report(LOG_RAW + 1, "Garmin: Char: %#02x\n", buf[i]);
    }

    if ('\x10' != buf[0]) {
	Send_NAK();
	gpsd_report(LOG_RAW + 1, "Garmin: buf[0] not DLE\n");
	return 0;
    }
    n = 1;
    pkt_id = buf[n++];
    chksum = pkt_id;
    if ('\x10' == pkt_id) {
	if ('\x10' != buf[n++]) {
	    Send_NAK();
	    gpsd_report(LOG_RAW + 1, "Garmin: Bad pkt_id %#02x\n", pkt_id);
	    return 0;
	}
    }

    pkt_len = buf[n++];
    chksum += pkt_len;
    if ('\x10' == pkt_len) {
	if ('\x10' != buf[n++]) {
	    gpsd_report(LOG_RAW + 1, "Garmin: Bad pkt_len %#02x\n", pkt_len);
	    Send_NAK();
	    return 0;
	}
    }
    data_index = 0;
    for (i = 0; i < 256; i++) {

	if ((int)pkt_len == data_index) {
	    // got it all
	    break;
	}
	if (len < n + i) {
	    gpsd_report(LOG_RAW + 1, "Garmin: Packet too short %zd < %zd\n",
			len, n + i);
	    Send_NAK();
	    return 0;
	}
	c = buf[n + i];
	if (got_dle) {
	    got_dle = 0;
	    if ('\x10' != c) {
		Send_NAK();
		gpsd_report(LOG_RAW + 1, "Garmin: Bad DLE %#02x\n", c);
		return 0;
	    }
	} else {
	    chksum += c;
	    data_buf[data_index++] = c;
	    if ('\x10' == c) {
		got_dle = 1;
	    }
	}
    }
    /* get checksum */
    if (len < n + i) {
	Send_NAK();
	gpsd_report(LOG_RAW + 1,
		    "Garmin: No checksum, Packet too short %zd < %zd\n", len,
		    n + i);
	return 0;
    }
    c = buf[n + i++];
    chksum += c;
    /* get final DLE */
    if (len < n + i) {
	Send_NAK();
	gpsd_report(LOG_RAW + 1,
		    "Garmin: No final DLE, Packet too short %zd < %zd\n", len,
		    n + i);
	return 0;
    }
    c = buf[n + i++];
    if ('\x10' != c) {
	Send_NAK();
	gpsd_report(LOG_RAW + 1, "Garmin: Final DLE not DLE\n");
	return 0;
    }
    /* get final ETX */
    if (len < n + i) {
	Send_NAK();
	gpsd_report(LOG_RAW + 1,
		    "Garmin: No final ETX, Packet too short %zd < %zd\n", len,
		    n + i);
	return 0;
    }
    /* we used to say n++ here, but scan-build complains */
    c = buf[n + i];
    if ('\x03' != c) {
	Send_NAK();
	gpsd_report(LOG_RAW + 1, "Garmin: Final ETX not ETX\n");
	return 0;
    }

    /* debug */
    /*@ -usedef -compdef @*/
    for (i = 0; i < data_index; i++) {
	gpsd_report(LOG_RAW + 1, "Garmin: Char: %#02x\n", data_buf[i]);
    }


    gpsd_report(LOG_IO,
		"Garmin: garmin_ser_parse() Type: %#02x, Len: %#02x, chksum: %#02x\n",
		pkt_id, pkt_len, chksum);
    mask = PrintSERPacket(session, pkt_id, pkt_len, data_buf);

    // sending ACK too soon might hang the session
    // so send ACK last, after a pause
    (void)usleep(300);
    Send_ACK();
    /*@ +usedef +compdef @*/
    gpsd_report(LOG_IO, "Garmin: garmin_ser_parse( )\n");
    return mask;
}

/*@ -charint @*/

#ifdef RECONFIGURE_ENABLE
static void settle(void)
{
    struct timespec delay, rem;
    /*@ -type -unrecog @*/
    memset(&delay, 0, sizeof(delay));
    delay.tv_sec = 0;
    delay.tv_nsec = 333000000L;
    nanosleep(&delay, &rem);
    /*@ +type +unrecog @*/
}

static void garmin_switcher(struct gps_device_t *session, int mode)
{
    if (mode == MODE_NMEA) {
	/*@ +charint @*/
	const char switcher[] =
	    { 0x10, 0x0A, 0x02, 0x26, 0x00, 0xCE, 0x10, 0x03 };
	// Note hard-coded string length in the next line...
	ssize_t status = gpsd_write(session, switcher, sizeof(switcher));
	/*@ -charint @*/
	if (status == (ssize_t)sizeof(switcher)) {
	    gpsd_report(LOG_IO,
			"Garmin: => GPS: turn off binary %02x %02x %02x... \n",
			switcher[0], switcher[1], switcher[2]);
	    session->gpsdata.dev.driver_mode = MODE_NMEA;
	} else {
	    gpsd_report(LOG_ERROR, "Garmin: => GPS: FAILED\n");
	}
	settle();		// wait 333mS, essential!

	/* once a sec, no binary, no averaging, NMEA 2.3, WAAS */
	(void)nmea_send(session, "$PGRMC1,1,1");
	//(void)nmea_send(fd, "$PGRMC1,1,1,1,,,,2,W,N");
	(void)nmea_send(session, "$PGRMI,,,,,,,R");
	settle();		// wait 333mS, essential!
    } else {
	(void)nmea_send(session, "$PGRMC1,1,2,1,,,,2,W,N");
	(void)nmea_send(session, "$PGRMI,,,,,,,R");
	session->gpsdata.dev.driver_mode = MODE_BINARY;
	settle();		// wait 333mS, essential!
    }
}
#endif /* RECONFIGURE_ENABLE */

#ifdef CONTROLSEND_ENABLE
static ssize_t garmin_control_send(struct gps_device_t *session,
				   char *buf, size_t buflen)
/* not used by the daemon, it's for gpsctl and friends */
{
    /*@ -mayaliasunique @*/
    session->msgbuflen = buflen;
    (void)memcpy(session->msgbuf, buf, buflen);
    return gpsd_write(session, session->msgbuf, session->msgbuflen);
    /*@ +mayaliasunique @*/
}
#endif /* CONTROLSEND_ENABLE */

#ifdef NTPSHM_ENABLE
static double garmin_ntp_offset(struct gps_device_t *session)
{
    if (session->sourcetype == source_usb) {
	return 0.035;		/* Garmin USB, expect +/- 40mS jitter */
    }
    /* only two sentences ships time */
    /* but the PVT data is always first */
    switch (session->gpsdata.dev.baudrate) {
    case 4800:
	return 0.430;		/* TBD */
    case 9600:
	return 0.430;		/* tested 12Arp10 */
    case 19200:
	return 0.430;		/* TBD */
    case 38400:
	return 0.430;		/* TBD */
    }
    return 0.430;		/* WTF?  WAG */
}
#endif /* NTPSHM_ENABLE */

/* this is everything we export */
#ifdef __UNUSED__
static int GetPacket(struct gps_device_t *session);
//-----------------------------------------------------------------------------
// Gets a single packet.
// this is odd, the garmin usb driver will only return 64 bytes, or less
// at a time, no matter what you ask for.
//
// is you ask for less than 64 bytes then the next packet will include
// just the remaining bytes of the last 64 byte packet.
//
// Reading a packet of length Zero, or less than 64, signals the end of
// the entire packet.
//
// The Garmin sample WinXX code also assumes the same behavior, so
// maybe it is something in the USB protocol.
//
// Return: 0 = got a good packet
//       -1 = error
//       1 = got partial packet
static int GetPacket(struct gps_device_t *session)
{
    struct timespec delay, rem;
    int cnt = 0;
    // int x = 0; // for debug dump

    memset(session->driver.garmin.Buffer, 0, sizeof(Packet_t));
    memset(&delay, 0, sizeof(delay));
    session->driver.garmin.BufferLen = 0;
    session->packet.outbuflen = 0;

    gpsd_report(LOG_IO, "Garmin: GetPacket()\n");

    for (cnt = 0; cnt < 10; cnt++) {
	size_t pkt_size;
	// Read async data until the driver returns less than the
	// max async data size, which signifies the end of a packet

	// not optimal, but given the speed and packet nature of
	// the USB not too bad for a start
	ssize_t theBytesReturned = 0;
	uint8_t *buf = (uint8_t *) session->driver.garmin.Buffer;
	Packet_t *thePacket = (Packet_t *) buf;

	theBytesReturned =
	    read(session->gpsdata.gps_fd,
		 buf + session->driver.garmin.BufferLen, ASYNC_DATA_SIZE);
	// zero byte returned is a legal value and denotes the end of a
	// binary packet.
	if (0 > theBytesReturned) {
	    // read error...
	    // or EAGAIN, but O_NONBLOCK is never set
	    gpsd_report(LOG_ERROR,
			"Garmin: GetPacket() read error=%d, errno=%d\n",
			theBytesReturned, errno);
	    continue;
	}
	gpsd_report(LOG_RAW, "Garmin: got %d bytes\n", theBytesReturned);

	session->driver.garmin.BufferLen += theBytesReturned;
	if (256 <= session->driver.garmin.BufferLen) {
	    // really bad read error...
	    gpsd_report(LOG_ERROR,
			"Garmin: GetPacket() packet too long, %ld > 255 !\n",
			session->driver.garmin.BufferLen);
	    session->driver.garmin.BufferLen = 0;
	    break;
	}
	pkt_size = 12 + get_int32((uint8_t *) & thePacket->mDataSize);
	if (12 <= session->driver.garmin.BufferLen) {
	    // have enough data to check packet size
	    if (session->driver.garmin.BufferLen > pkt_size) {
		// wrong amount of data in buffer
		gpsd_report(LOG_ERROR,
			    "Garmin: GetPacket() packet size wrong! Packet: %ld, s/b %ld\n",
			    session->driver.garmin.BufferLen, pkt_size);
		session->driver.garmin.BufferLen = 0;
		break;
	    }
	}
	if (64 > theBytesReturned) {
	    // zero length, or short, read is a flag for got the whole packet
	    break;
	}


	/*@ ignore @*/
	delay.tv_sec = 0;
	delay.tv_nsec = 3330000L;
	while (nanosleep(&delay, &rem) == -1)
	    continue;
	/*@ end @*/
    }
    // dump the individual bytes, debug only
    // for ( x = 0; x < session->driver.garmin.BufferLen; x++ ) {
    // gpsd_report(LOG_RAW+1, "Garmin: p[%d] = %x\n", x, session->driver.garmin.Buffer[x]);
    // }
    if (10 <= cnt) {
	gpsd_report(LOG_ERROR,
		    "Garmin: GetPacket() packet too long or too slow!\n");
	return -1;
    }

    gpsd_report(LOG_RAW, "Garmin: GotPacket() sz=%d \n",
		session->driver.garmin.BufferLen);
    session->packet.outbuflen = session->driver.garmin.BufferLen;
    return 0;
}

static gps_mask_t garmin_usb_parse(struct gps_device_t *session)
{
    gpsd_report(LOG_PROG, "Garmin: garmin_usb_parse()\n");
    return PrintUSBPacket(session,
			  (Packet_t *) session->driver.garmin.Buffer);
}

static ssize_t garmin_get_packet(struct gps_device_t *session)
{
    return (ssize_t) (0 == GetPacket(session) ? 1 : 0);
}

/* *INDENT-OFF* */
const struct gps_type_t garmin_usb_binary_old =
{
    .type_name      = "Garmin USB binary",	/* full name of type */
    .packet_type    = GARMIN_PACKET;	/* associated lexer packet type */
    .flags	    = DRIVER_NOFLAGS,	/* no flags set */
    .trigger        = NULL,		/* no trigger, it has a probe */
    .channels       = GARMIN_CHANNELS,	/* consumer-grade GPS */
    .probe_detect   = garmin_usb_detect,/* how to detect at startup time */
    .get_packet     = garmin_get_packet,/* how to grab a packet */
    .parse_packet   = garmin_usb_parse,	/* parse message packets */
    .rtcm_writer    = NULL,		/* don't send DGPS corrections */
    .event_hook     = garmin_event_hook,/* lifetime event handler */
#ifdef RECONFIGURE_ENABLE
    .speed_switcher = NULL,		/* no speed switcher */
    .mode_switcher  = NULL,		/* no mode switcher */
    .rate_switcher  = NULL,		/* no sample-rate switcher */
    .min_cycle      = 1,		/* not relevant, no rate switch */
#endif /* RECONFIGURE_ENABLE */
#ifdef CONTROLSEND_ENABLE
    .control_send   = garmin_control_send,	/* send raw bytes */
#endif /* CONTROLSEND_ENABLE */
#ifdef NTPSHM_ENABLE
    .ntp_offset     = garmin_ntp_offset,
#endif /* NTPSHM_ ENABLE */
};
/* *INDENT-ON* */
#endif /* __UNUSED__ */

/* *INDENT-OFF* */
const struct gps_type_t garmin_usb_binary =
{
    .type_name      = "Garmin USB binary",	/* full name of type */
    .packet_type    = GARMIN_PACKET,	/* associated lexer packet type */
    .flags	    = DRIVER_NOFLAGS,	/* no flags set */
    .trigger        = NULL,		/* no trigger, it has a probe */
    .channels       = GARMIN_CHANNELS,	/* consumer-grade GPS */
    .probe_detect   = garmin_usb_detect,/* how to detect at startup time */
    .get_packet     = generic_get,      /* how to grab a packet */
    .parse_packet   = garmin_ser_parse,	/* parse message packets */
    .rtcm_writer    = NULL,		/* don't send DGPS corrections */
    .event_hook     = garmin_event_hook,/* lifetime ebent handler */
#ifdef RECONFIGURE_ENABLE
    .speed_switcher = NULL,		/* no speed switcher */
    .mode_switcher  = NULL,	        /* Garmin USB Binary has no NMEA */
    .rate_switcher  = NULL,		/* no sample-rate switcher */
    .min_cycle      = 1,		/* not relevant, no rate switch */
#endif /* RECONFIGURE_ENABLE */
#ifdef CONTROLSEND_ENABLE
    .control_send   = garmin_control_send,	/* send raw bytes */
#endif /* CONTROLSEND_ENABLE */
#ifdef NTPSHM_ENABLE
    .ntp_offset     = garmin_ntp_offset,
#endif /* NTPSHM_ ENABLE */
};
/* *INDENT-ON* */

/* *INDENT-OFF* */
const struct gps_type_t garmin_ser_binary =
{
    .type_name      = "Garmin Serial binary",	/* full name of type */
    .packet_type    = GARMIN_PACKET,	/* associated lexer packet type */
    .flags	    = DRIVER_NOFLAGS,	/* no flags set */
    .trigger        = NULL,		/* no trigger, it has a probe */
    .channels       = GARMIN_CHANNELS,	/* consumer-grade GPS */
    .probe_detect   = NULL,        	/* how to detect at startup time */
    .get_packet     = generic_get,       /* how to grab a packet */
    .parse_packet   = garmin_ser_parse,	/* parse message packets */
    .rtcm_writer    = NULL,		/* don't send DGPS corrections */
    .event_hook     = NULL,	        /* lifetime event handler */
#ifdef RECONFIGURE_ENABLE
    .speed_switcher = NULL,		/* no speed switcher */
    .mode_switcher  = garmin_switcher,	/* how to change modes */
    .rate_switcher  = NULL,		/* no sample-rate switcher */
    .min_cycle      = 1,		/* not relevant, no rate switch */
#endif /* RECONFIGURE_ENABLE */
#ifdef CONTROLSEND_ENABLE
    .control_send   = garmin_control_send,	/* send raw bytes */
#endif /* CONTROLSEND_ENABLE */
#ifdef NTPSHM_ENABLE
    .ntp_offset     = garmin_ntp_offset,
#endif /* NTPSHM_ ENABLE */
};
/* *INDENT-ON* */

#endif /* GARMIN_ENABLE */