/*****************************************************************************
This is a decoder for RTCM-104 2.x, an obscure and complicated serial
protocol used for broadcasting pseudorange corrections from
differential-GPS reference stations. The applicable
standard is
RTCM RECOMMENDED STANDARDS FOR DIFFERENTIAL GNSS (GLOBAL NAVIGATION
SATELLITE) SERVICE, VERSION 2.3 (RTCM PAPER 136-2001/SC104-STD)
Ordering instructions are accessible from
under "Publications". This describes version 2.3 of the RTCM specification.
RTCM-104 was later completely redesigned as level 3.0.
Also applicable is ITU-R M.823: "Technical characteristics of
differential transmissions for global navigation satellite systems
from maritime radio beacons in the frequency band 283.5 - 315 kHz in
region 1 and 285 - 325 kHz in regions 2 & 3."
The RTCM 2.x protocol uses as a transport layer the GPS satellite downlink
protocol described in IS-GPS-200, the Navstar GPS Interface
Specification. This code relies on the lower-level packet-assembly
code for that protocol in isgps.c.
The lower layer's job is done when it has assembled a message of up to
33 30-bit words of clean parity-checked data. At this point this upper layer
takes over. struct rtcm2_msg_t is overlaid on the buffer and the bitfields
are used to extract pieces of it. Those pieces are copied and (where
necessary) reassembled into a struct rtcm2_t.
This code and the contents of isgps.c are evolved from code by
Wolfgang Rupprecht. Wolfgang's decoder was loosely based on one
written by John Sager in 1999. Here are John Sager's original notes:
The RTCM decoder prints a legible representation of the input data.
The RTCM SC-104 specification is copyrighted, so I cannot
quote it - in fact, I have never read it! Most of the information
used to develop the decoder came from publication ITU-R M.823.
This is a specification of the data transmitted from LF DGPS
beacons in the 300kHz band. M.823 contains most of those parts of
RTCM SC-104 directly relevant to the air interface (there
are one or two annoying and vital omissions!). Information
about the serial interface format was gleaned from studying
the output of a beacon receiver test program made available on
Starlink's website.
This code has been checked against ASCII dumps made by a proprietary
decoder running under Windows and is known to be consistent with it
with respect to message types 1, 3, 9, 14, 16, and 31. Decoding of
message types 4, 5, 6, 7, and 13 has not been checked. Message types
8, 10-12, 15-27, 28-30 (undefined), 31-37, 38-58 (undefined), and
60-63 are not yet supported.
This file is Copyright (c) 2010 by the GPSD project
BSD terms apply: see the file COPYING in the distribution root for details.
*****************************************************************************/
#include
#include
#include "gpsd.h"
/*
* Structures for interpreting words in an RTCM-104 2.x message (after
* parity checking and removing inversion). Note, these structures
* are overlayed on the raw data in order to decode them into
* bitfields; this will fail horribly if your C compiler introduces
* padding between or before bit fields, or between 8-bit-aligned
* bitfields and character arrays despite #pragma pack(1). The right
* things happen under gcc 4.x on amd64, i386, ia64, all arm and mips
* variants, m68k, and powerpc)
*
* (In practice, the only class of machines on which this is likely
* to fail are word-aligned architectures without barrel shifters.
* Very few of these are left in 2012. By test, we know of s390, s390x,
* and sparc.)
*
* The RTCM 2.1 standard is less explicit than it should be about signed-integer
* representations. Two's complement is specified for some but not all.
*/
#define ZCOUNT_SCALE 0.6 /* sec */
#define PRCSMALL 0.02 /* meters */
#define PRCLARGE 0.32 /* meters */
#define RRSMALL 0.002 /* meters/sec */
#define RRLARGE 0.032 /* meters/sec */
#define MAXPCSMALL (0x7FFF * PCSMALL) /* 16-bits signed */
#define MAXRRSMALL (0x7F * RRSMALL) /* 8-bits signed */
#define XYZ_SCALE 0.01 /* meters */
#define DXYZ_SCALE 0.1 /* meters */
#define LA_SCALE (90.0/32767.0) /* degrees */
#define LO_SCALE (180.0/32767.0) /* degrees */
#define FREQ_SCALE 0.1 /* kHz */
#define FREQ_OFFSET 190.0 /* kHz */
#define CNR_OFFSET 24 /* dB */
#define TU_SCALE 5 /* minutes */
#define LATLON_SCALE 0.01 /* degrees */
#define RANGE_SCALE 4 /* kilometers */
#pragma pack(1)
/*
* Reminder: Emacs reverse-region is useful...
*/
#ifndef WORDS_BIGENDIAN /* little-endian, like x86 */
struct rtcm2_msg_t {
struct rtcm2_msghw1 { /* header word 1 */
uint parity:6;
uint refstaid:10; /* reference station ID */
uint msgtype:6; /* RTCM message type */
uint preamble:8; /* fixed at 01100110 */
uint _pad:2;
} w1;
struct rtcm2_msghw2 { /* header word 2 */
uint parity:6;
uint stathlth:3; /* station health */
uint frmlen:5;
uint sqnum:3;
uint zcnt:13;
uint _pad:2;
} w2;
union {
/* msg 1 - differential gps corrections */
struct rtcm2_msg1 {
struct gps_correction_t {
struct { /* msg 1 word 3 */
uint parity:6;
int prc1:16;
uint satident1:5; /* satellite ID */
uint udre1:2;
uint scale1:1;
uint _pad:2;
} w3;
struct { /* msg 1 word 4 */
uint parity:6;
uint satident2:5; /* satellite ID */
uint udre2:2;
uint scale2:1;
uint iod1:8;
int rrc1:8;
uint _pad:2;
} w4;
struct { /* msg 1 word 5 */
uint parity:6;
int rrc2:8;
int prc2:16;
uint _pad:2;
} w5;
struct { /* msg 1 word 6 */
uint parity:6;
int prc3_h:8;
uint satident3:5; /* satellite ID */
uint udre3:2;
uint scale3:1;
uint iod2:8;
uint _pad:2;
} w6;
struct { /* msg 1 word 7 */
uint parity:6;
uint iod3:8;
int rrc3:8;
uint prc3_l:8; /* NOTE: uint for low byte */
uint _pad:2;
} w7;
} corrections[(RTCM2_WORDS_MAX - 2) / 5];
} type1;
/* msg 3 - reference station parameters */
struct rtcm2_msg3 {
struct {
uint parity:6;
uint x_h:24;
uint _pad:2;
} w3;
struct {
uint parity:6;
uint y_h:16;
uint x_l:8;
uint _pad:2;
} w4;
struct {
uint parity:6;
uint z_h:8;
uint y_l:16;
uint _pad:2;
} w5;
struct {
uint parity:6;
uint z_l:24;
uint _pad:2;
} w6;
} type3;
/* msg 4 - reference station datum */
struct rtcm2_msg4 {
struct {
uint parity:6;
uint datum_alpha_char2:8;
uint datum_alpha_char1:8;
uint spare:4;
uint dat:1;
uint dgnss:3;
uint _pad:2;
} w3;
struct {
uint parity:6;
uint datum_sub_div_char2:8;
uint datum_sub_div_char1:8;
uint datum_sub_div_char3:8;
uint _pad:2;
} w4;
struct {
uint parity:6;
uint dy_h:8;
uint dx:16;
uint _pad:2;
} w5;
struct {
uint parity:6;
uint dz:24;
uint dy_l:8;
uint _pad:2;
} w6;
} type4;
/* msg 5 - constellation health */
struct rtcm2_msg5 {
struct b_health_t {
uint parity:6;
uint unassigned:2;
uint time_unhealthy:4;
uint loss_warn:1;
uint new_nav_data:1;
uint health_enable:1;
uint cn0:5;
uint data_health:3;
uint issue_of_data_link:1;
uint sat_id:5;
uint reserved:1;
uint _pad:2;
} health[MAXHEALTH];
} type5;
/* msg 6 - null message */
/* msg 7 - beacon almanac */
struct rtcm2_msg7 {
struct b_station_t {
struct {
uint parity:6;
int lon_h:8;
int lat:16;
uint _pad:2;
} w3;
struct {
uint parity:6;
uint freq_h:6;
uint range:10;
uint lon_l:8;
uint _pad:2;
} w4;
struct {
uint parity:6;
uint encoding:1;
uint sync_type:1;
uint mod_mode:1;
uint bit_rate:3;
/*
* ITU-R M.823-2 page 9 and RTCM-SC104 v2.1 pages
* 4-21 and 4-22 are in conflict over the next two
* field sizes. ITU says 9+3, RTCM says 10+2.
* The latter correctly decodes the USCG station
* id's so I'll use that one here. -wsr
*/
uint station_id:10;
uint health:2;
uint freq_l:6;
uint _pad:2;
} w5;
} almanac[(RTCM2_WORDS_MAX - 2)/3];
} type7;
/* msg 13 - Ground Transmitter Parameters (RTCM2.3 only) */
struct rtcm2_msg13 {
struct {
uint parity:6;
int lat:16;
uint reserved:6;
uint rangeflag:1;
uint status:1;
uint _pad:2;
} w1;
struct {
uint parity:6;
uint range:8;
int lon:16;
uint _pad:2;
} w2;
} type13;
/* msg 14 - GPS Time of Week (RTCM2.3 only) */
struct rtcm2_msg14 {
struct {
uint parity:6;
uint leapsecs:6;
uint hour:8;
uint week:10;
uint _pad:2;
} w1;
} type14;
/* msg 16 - text msg */
struct rtcm2_msg16 {
struct {
uint parity:6;
uint byte3:8;
uint byte2:8;
uint byte1:8;
uint _pad:2;
} txt[RTCM2_WORDS_MAX-2];
} type16;
/* msg 31 - differential GLONASS corrections */
struct rtcm2_msg31 {
struct glonass_correction_t {
struct { /* msg 1 word 3 */
uint parity:6;
int prc1:16;
uint satident1:5; /* satellite ID */
uint udre1:2;
uint scale1:1;
uint _pad:2;
} w3;
struct { /* msg 1 word 4 */
uint parity:6;
uint satident2:5; /* satellite ID */
uint udre2:2;
uint scale2:1;
uint tod1:7;
uint change1:1;
int rrc1:8;
uint _pad:2;
} w4;
struct { /* msg 1 word 5 */
uint parity:6;
int rrc2:8;
int prc2:16;
uint _pad:2;
} w5;
struct { /* msg 1 word 6 */
uint parity:6;
int prc3_h:8;
uint satident3:5; /* satellite ID */
uint udre3:2;
uint scale3:1;
uint tod2:7;
uint change2:1;
uint _pad:2;
} w6;
struct { /* msg 1 word 7 */
uint parity:6;
uint tod3:7;
uint change3:1;
int rrc3:8;
uint prc3_l:8; /* NOTE: uint for low byte */
uint _pad:2;
} w7;
} corrections[(RTCM2_WORDS_MAX - 2) / 5];
} type31;
/* unknown message */
isgps30bits_t rtcm2_msgunk[RTCM2_WORDS_MAX-2];
} msg_type;
};
#endif /* LITTLE_ENDIAN */
#ifdef WORDS_BIGENDIAN
#ifndef S_SPLINT_S /* splint thinks it's a duplicate definition */
struct rtcm2_msg_t {
struct rtcm2_msghw1 { /* header word 1 */
uint _pad:2;
uint preamble:8; /* fixed at 01100110 */
uint msgtype:6; /* RTCM message type */
uint refstaid:10; /* reference station ID */
uint parity:6;
} w1;
struct rtcm2_msghw2 { /* header word 2 */
uint _pad:2;
uint zcnt:13;
uint sqnum:3;
uint frmlen:5;
uint stathlth:3; /* station health */
uint parity:6;
} w2;
union {
/* msg 1 - differential GPS corrections */
struct rtcm2_msg1 {
struct gps_correction_t {
struct { /* msg 1 word 3 */
uint _pad:2;
uint scale1:1;
uint udre1:2;
uint satident1:5; /* satellite ID */
int prc1:16;
uint parity:6;
} w3;
struct { /* msg 1 word 4 */
uint _pad:2;
int rrc1:8;
uint iod1:8;
uint scale2:1;
uint udre2:2;
uint satident2:5; /* satellite ID */
uint parity:6;
} w4;
struct { /* msg 1 word 5 */
uint _pad:2;
int prc2:16;
int rrc2:8;
uint parity:6;
} w5;
struct { /* msg 1 word 6 */
uint _pad:2;
uint iod2:8;
uint scale3:1;
uint udre3:2;
uint satident3:5; /* satellite ID */
int prc3_h:8;
uint parity:6;
} w6;
struct { /* msg 1 word 7 */
uint _pad:2;
uint prc3_l:8; /* NOTE: uint for low byte */
int rrc3:8;
uint iod3:8;
uint parity:6;
} w7;
} corrections[(RTCM2_WORDS_MAX - 2) / 5];
} type1;
/* msg 3 - reference station parameters */
struct rtcm2_msg3 {
struct {
uint _pad:2;
uint x_h:24;
uint parity:6;
} w3;
struct {
uint _pad:2;
uint x_l:8;
uint y_h:16;
uint parity:6;
} w4;
struct {
uint _pad:2;
uint y_l:16;
uint z_h:8;
uint parity:6;
} w5;
struct {
uint _pad:2;
uint z_l:24;
uint parity:6;
} w6;
} type3;
/* msg 4 - reference station datum */
struct rtcm2_msg4 {
struct {
uint _pad:2;
uint dgnss:3;
uint dat:1;
uint spare:4;
uint datum_alpha_char1:8;
uint datum_alpha_char2:8;
uint parity:6;
} w3;
struct {
uint _pad:2;
uint datum_sub_div_char3:8;
uint datum_sub_div_char1:8;
uint datum_sub_div_char2:8;
uint parity:6;
} w4;
struct {
uint _pad:2;
uint dx:16;
uint dy_h:8;
uint parity:6;
} w5;
struct {
uint _pad:2;
uint dy_l:8;
uint dz:24;
uint parity:6;
} w6;
} type4;
/* msg 5 - constellation health */
struct rtcm2_msg5 {
struct b_health_t {
uint _pad:2;
uint reserved:1;
uint sat_id:5;
uint issue_of_data_link:1;
uint data_health:3;
uint cn0:5;
uint health_enable:1;
uint new_nav_data:1;
uint loss_warn:1;
uint time_unhealthy:4;
uint unassigned:2;
uint parity:6;
} health[MAXHEALTH];
} type5;
/* msg 6 - null message */
/* msg 7 - beacon almanac */
struct rtcm2_msg7 {
struct b_station_t {
struct {
uint _pad:2;
int lat:16;
int lon_h:8;
uint parity:6;
} w3;
struct {
uint _pad:2;
uint lon_l:8;
uint range:10;
uint freq_h:6;
uint parity:6;
} w4;
struct {
uint _pad:2;
uint freq_l:6;
uint health:2;
uint station_id:10;
/* see comments in LE struct above. */
uint bit_rate:3;
uint mod_mode:1;
uint sync_type:1;
uint encoding:1;
uint parity:6;
} w5;
} almanac[(RTCM2_WORDS_MAX - 2)/3];
} type7;
/* msg 13 - Ground Transmitter Parameters (RTCM2.3 only) */
struct rtcm2_msg13 {
struct {
uint _pad:2;
uint status:1;
uint rangeflag:1;
uint reserved:6;
int lat:16;
uint parity:6;
} w1;
struct {
uint _pad:2;
int lon:16;
uint range:8;
uint parity:6;
} w2;
} type13;
/* msg 14 - GPS Time of Week (RTCM2.3 only) */
struct rtcm2_msg14 {
struct {
uint _pad:2;
uint week:10;
uint hour:8;
uint leapsecs:6;
uint parity:6;
} w1;
} type14;
/* msg 16 - text msg */
struct rtcm2_msg16 {
struct {
uint _pad:2;
uint byte1:8;
uint byte2:8;
uint byte3:8;
uint parity:6;
} txt[RTCM2_WORDS_MAX-2];
} type16;
/* msg 31 - differential GLONASS corrections */
struct rtcm2_msg31 {
struct glonass_correction_t {
struct { /* msg 1 word 3 */
uint _pad:2;
uint scale1:1;
uint udre1:2;
uint satident1:5; /* satellite ID */
int prc1:16;
uint parity:6;
} w3;
struct { /* msg 1 word 4 */
uint _pad:2;
int rrc1:8;
uint change1:1;
uint tod1:7;
uint scale2:1;
uint udre2:2;
uint satident2:5; /* satellite ID */
uint parity:6;
} w4;
struct { /* msg 1 word 5 */
uint _pad:2;
int prc2:16;
int rrc2:8;
uint parity:6;
} w5;
struct { /* msg 1 word 6 */
uint _pad:2;
uint change2:1;
uint tod2:7;
uint scale3:1;
uint udre3:2;
uint satident3:5; /* satellite ID */
int prc3_h:8;
uint parity:6;
} w6;
struct { /* msg 1 word 7 */
uint _pad:2;
uint prc3_l:8; /* NOTE: uint for low byte */
int rrc3:8;
uint change3:1;
uint tod3:7;
uint parity:6;
} w7;
} corrections[(RTCM2_WORDS_MAX - 2) / 5];
} type31;
/* unknown message */
isgps30bits_t rtcm2_msgunk[RTCM2_WORDS_MAX-2];
} msg_type;
};
#endif /* S_SPLINT_S */
#endif /* BIG ENDIAN */
#ifdef RTCM104V2_ENABLE
#define PREAMBLE_PATTERN 0x66
static unsigned int tx_speed[] = { 25, 50, 100, 110, 150, 200, 250, 300 };
#define DIMENSION(a) (unsigned)(sizeof(a)/sizeof(a[0]))
void rtcm2_unpack( /*@out@*/ struct rtcm2_t *tp, char *buf)
/* break out the raw bits into the content fields */
{
int len;
unsigned int n, w;
struct rtcm2_msg_t *msg = (struct rtcm2_msg_t *)buf;
tp->type = msg->w1.msgtype;
tp->length = msg->w2.frmlen;
tp->zcount = msg->w2.zcnt * ZCOUNT_SCALE;
tp->refstaid = msg->w1.refstaid;
tp->seqnum = msg->w2.sqnum;
tp->stathlth = msg->w2.stathlth;
len = (int)tp->length;
n = 0;
switch (tp->type) {
case 1:
case 9:
{
struct gps_correction_t *m = &msg->msg_type.type1.corrections[0];
while (len >= 0) {
if (len >= 2) {
tp->gps_ranges.sat[n].ident = m->w3.satident1;
tp->gps_ranges.sat[n].udre = m->w3.udre1;
tp->gps_ranges.sat[n].iod = m->w4.iod1;
tp->gps_ranges.sat[n].prc = m->w3.prc1 *
(m->w3.scale1 ? PRCLARGE : PRCSMALL);
tp->gps_ranges.sat[n].rrc = m->w4.rrc1 *
(m->w3.scale1 ? RRLARGE : RRSMALL);
n++;
}
if (len >= 4) {
tp->gps_ranges.sat[n].ident = m->w4.satident2;
tp->gps_ranges.sat[n].udre = m->w4.udre2;
tp->gps_ranges.sat[n].iod = m->w6.iod2;
tp->gps_ranges.sat[n].prc = m->w5.prc2 *
(m->w4.scale2 ? PRCLARGE : PRCSMALL);
tp->gps_ranges.sat[n].rrc = m->w5.rrc2 *
(m->w4.scale2 ? RRLARGE : RRSMALL);
n++;
}
if (len >= 5) {
tp->gps_ranges.sat[n].ident = m->w6.satident3;
tp->gps_ranges.sat[n].udre = m->w6.udre3;
tp->gps_ranges.sat[n].iod = m->w7.iod3;
/*@ -shiftimplementation @*/
tp->gps_ranges.sat[n].prc =
((m->w6.prc3_h << 8) | (m->w7.prc3_l)) *
(m->w6.scale3 ? PRCLARGE : PRCSMALL);
tp->gps_ranges.sat[n].rrc =
m->w7.rrc3 * (m->w6.scale3 ? RRLARGE : RRSMALL);
/*@ +shiftimplementation @*/
n++;
}
len -= 5;
m++;
}
tp->gps_ranges.nentries = n;
}
break;
case 3:
{
struct rtcm2_msg3 *m = &msg->msg_type.type3;
if ((tp->ecef.valid = len >= 4)) {
tp->ecef.x = ((m->w3.x_h << 8) | (m->w4.x_l)) * XYZ_SCALE;
tp->ecef.y = ((m->w4.y_h << 16) | (m->w5.y_l)) * XYZ_SCALE;
tp->ecef.z = ((m->w5.z_h << 24) | (m->w6.z_l)) * XYZ_SCALE;
}
}
break;
case 4:
if ((tp->reference.valid = len >= 2)) {
struct rtcm2_msg4 *m = &msg->msg_type.type4;
tp->reference.system =
(m->w3.dgnss == 0) ? NAVSYSTEM_GPS :
((m->w3.dgnss == 1) ? NAVSYSTEM_GLONASS : NAVSYSTEM_UNKNOWN);
tp->reference.sense =
(m->w3.dat != 0) ? SENSE_GLOBAL : SENSE_LOCAL;
if (m->w3.datum_alpha_char1) {
tp->reference.datum[n++] = (char)(m->w3.datum_alpha_char1);
}
if (m->w3.datum_alpha_char2) {
tp->reference.datum[n++] = (char)(m->w3.datum_alpha_char2);
}
if (m->w4.datum_sub_div_char1) {
tp->reference.datum[n++] = (char)(m->w4.datum_sub_div_char1);
}
if (m->w4.datum_sub_div_char2) {
tp->reference.datum[n++] = (char)(m->w4.datum_sub_div_char2);
}
if (m->w4.datum_sub_div_char3) {
tp->reference.datum[n++] = (char)(m->w4.datum_sub_div_char3);
}
/* we used to say n++ here, but scan-build complains */
tp->reference.datum[n] = '\0';
if (len >= 4) {
tp->reference.dx = m->w5.dx * DXYZ_SCALE;
tp->reference.dy =
((m->w5.dy_h << 8) | m->w6.dy_l) * DXYZ_SCALE;
tp->reference.dz = m->w6.dz * DXYZ_SCALE;
} else
tp->reference.sense = SENSE_INVALID;
}
break;
case 5:
for (n = 0; n < (unsigned)len; n++) {
struct consat_t *csp = &tp->conhealth.sat[n];
struct b_health_t *m = &msg->msg_type.type5.health[n];
csp->ident = m->sat_id;
csp->iodl = m->issue_of_data_link != 0;
csp->health = m->data_health;
/*@+ignoresigns@*/
csp->snr = (int)(m->cn0 ? (m->cn0 + CNR_OFFSET) : SNR_BAD);
/*@-ignoresigns@*/
csp->health_en = m->health_enable != 0;
csp->new_data = m->new_nav_data != 0;
csp->los_warning = m->loss_warn != 0;
csp->tou = m->time_unhealthy * TU_SCALE;
}
tp->conhealth.nentries = n;
break;
case 7:
for (w = 0; w < (unsigned)len; w++) {
struct station_t *np = &tp->almanac.station[n];
struct b_station_t *mp = &msg->msg_type.type7.almanac[w];
np->latitude = mp->w3.lat * LA_SCALE;
/*@-shiftimplementation@*/
np->longitude = ((mp->w3.lon_h << 8) | mp->w4.lon_l) * LO_SCALE;
/*@+shiftimplementation@*/
np->range = mp->w4.range;
np->frequency =
(((mp->w4.freq_h << 6) | mp->w5.freq_l) * FREQ_SCALE) +
FREQ_OFFSET;
np->health = mp->w5.health;
np->station_id = mp->w5.station_id,
np->bitrate = tx_speed[mp->w5.bit_rate];
n++;
}
tp->almanac.nentries = (unsigned)(len / 3);
break;
case 13:
tp->xmitter.status = (bool)msg->msg_type.type13.w1.status;
tp->xmitter.rangeflag = (bool)msg->msg_type.type13.w1.rangeflag;
tp->xmitter.lat = msg->msg_type.type13.w1.lat * LATLON_SCALE;
tp->xmitter.lon = msg->msg_type.type13.w2.lon * LATLON_SCALE;
tp->xmitter.range = msg->msg_type.type13.w2.range * RANGE_SCALE;
if (tp->xmitter.range == 0)
tp->xmitter.range = 1024;
break;
case 14:
tp->gpstime.week = msg->msg_type.type14.w1.week;
tp->gpstime.hour = msg->msg_type.type14.w1.hour;
tp->gpstime.leapsecs = msg->msg_type.type14.w1.leapsecs;
break;
case 16:
/*@ -boolops @*/
for (w = 0; w < (unsigned)len; w++) {
if (!msg->msg_type.type16.txt[w].byte1) {
break;
}
tp->message[n++] = (char)(msg->msg_type.type16.txt[w].byte1);
if (!msg->msg_type.type16.txt[w].byte2) {
break;
}
tp->message[n++] = (char)(msg->msg_type.type16.txt[w].byte2);
if (!msg->msg_type.type16.txt[w].byte3) {
break;
}
tp->message[n++] = (char)(msg->msg_type.type16.txt[w].byte3);
}
/*@ +boolops @*/
tp->message[n] = '\0';
break;
case 31:
{
struct glonass_correction_t *m = &msg->msg_type.type31.corrections[0];
while (len >= 0) {
if (len >= 2) {
tp->glonass_ranges.sat[n].ident = m->w3.satident1;
tp->glonass_ranges.sat[n].udre = m->w3.udre1;
tp->glonass_ranges.sat[n].change = (bool)m->w4.change1;
tp->glonass_ranges.sat[n].tod = m->w4.tod1;
tp->glonass_ranges.sat[n].prc = m->w3.prc1 *
(m->w3.scale1 ? PRCLARGE : PRCSMALL);
tp->glonass_ranges.sat[n].rrc = m->w4.rrc1 *
(m->w3.scale1 ? RRLARGE : RRSMALL);
n++;
}
if (len >= 4) {
tp->glonass_ranges.sat[n].ident = m->w4.satident2;
tp->glonass_ranges.sat[n].udre = m->w4.udre2;
tp->glonass_ranges.sat[n].change = (bool)m->w6.change2;
tp->glonass_ranges.sat[n].tod = m->w6.tod2;
tp->glonass_ranges.sat[n].prc = m->w5.prc2 *
(m->w4.scale2 ? PRCLARGE : PRCSMALL);
tp->glonass_ranges.sat[n].rrc = m->w5.rrc2 *
(m->w4.scale2 ? RRLARGE : RRSMALL);
n++;
}
if (len >= 5) {
tp->glonass_ranges.sat[n].ident = m->w6.satident3;
tp->glonass_ranges.sat[n].udre = m->w6.udre3;
tp->glonass_ranges.sat[n].change = (bool)m->w7.change3;
tp->glonass_ranges.sat[n].tod = m->w7.tod3;
/*@ -shiftimplementation @*/
tp->glonass_ranges.sat[n].prc =
((m->w6.prc3_h << 8) | (m->w7.prc3_l)) *
(m->w6.scale3 ? PRCLARGE : PRCSMALL);
tp->glonass_ranges.sat[n].rrc =
m->w7.rrc3 * (m->w6.scale3 ? RRLARGE : RRSMALL);
/*@ +shiftimplementation @*/
n++;
}
len -= 5;
m++;
}
tp->glonass_ranges.nentries = n;
}
break;
default:
memcpy(tp->words, msg->msg_type.rtcm2_msgunk,
(RTCM2_WORDS_MAX - 2) * sizeof(isgps30bits_t));
break;
}
}
static bool preamble_match(isgps30bits_t * w)
{
return (((struct rtcm2_msghw1 *)w)->preamble == PREAMBLE_PATTERN);
}
static bool length_check(struct gps_packet_t *lexer)
{
return lexer->isgps.bufindex >= 2
&& lexer->isgps.bufindex >=
((struct rtcm2_msg_t *)lexer->isgps.buf)->w2.frmlen + 2u;
}
enum isgpsstat_t rtcm2_decode(struct gps_packet_t *lexer, unsigned int c)
{
return isgps_decode(lexer,
preamble_match, length_check, RTCM2_WORDS_MAX, c);
}
#endif /* RTCM104V2_ENABLE */