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Complete the bFlags decoding

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Update the bFlags structure member to indicate which other structure
members contain decoded values.

Also, trim out mm structure members that are simple bitwise ands from
the raw data, unless the results are used in lots of places whereby
decoding them once is more efficient.
This commit is contained in:
Malcolm Robb 2013-05-09 15:29:25 +01:00
parent a3d62f96b7
commit fc7d1e27c9
1 changed files with 112 additions and 80 deletions
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dump1090.c
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@ -106,6 +106,14 @@
#define MODES_USER_LATLON_VALID (1<<0) #define MODES_USER_LATLON_VALID (1<<0)
#define MODES_ACFLAGS_LATLON_VALID (1<<0) // Aircraft Lat/Lon is known #define MODES_ACFLAGS_LATLON_VALID (1<<0) // Aircraft Lat/Lon is known
#define MODES_ACFLAGS_ALTITUDE_VALID (1<<1) // Aircraft altitude is known
#define MODES_ACFLAGS_HEADING_VALID (1<<2) // Aircraft heading is known
#define MODES_ACFLAGS_SPEED_VALID (1<<3) // Aircraft speed is known
#define MODES_ACFLAGS_VERTRATE_VALID (1<<4) // Aircraft vertical rate is known
#define MODES_ACFLAGS_SQUAWK_VALID (1<<5) // Aircraft Mode A Squawk is known
#define MODES_ACFLAGS_CALLSIGN_VALID (1<<6) // Aircraft Callsign Identity
#define MODES_ACFLAGS_EWSPEED_VALID (1<<7) // Aircraft East West Speed is known
#define MODES_ACFLAGS_NSSPEED_VALID (1<<8) // Aircraft North South Speed is known
#define MODES_ACFLAGS_AOG (1<<9) // Aircraft is On the Ground #define MODES_ACFLAGS_AOG (1<<9) // Aircraft is On the Ground
#define MODES_ACFLAGS_LATLON_REL_OK (1<<15) // Indicates it's OK to do a relative CPR #define MODES_ACFLAGS_LATLON_REL_OK (1<<15) // Indicates it's OK to do a relative CPR
@ -279,34 +287,26 @@ struct modesMessage {
unsigned char signalLevel; // Signal Amplitude unsigned char signalLevel; // Signal Amplitude
// DF 11 // DF 11
int ca; // Responder capabilities int ca; // Responder capabilities
int iid; int iid;
// DF 17 // DF 17
int metype; // Extended squitter message type. int metype; // Extended squitter message type.
int mesub; // Extended squitter message subtype. int mesub; // Extended squitter message subtype.
int heading_is_valid; int heading; // Reported by aircraft, or computed from from EW and NS velocity
int heading; // Reported by aircraft, or computed from from EW and NS velocity int raw_latitude; // Non decoded latitude.
int fflag; // 1 = Odd, 0 = Even CPR message. int raw_longitude; // Non decoded longitude.
int tflag; // UTC synchronized?
int raw_latitude; // Non decoded latitude.
int raw_longitude; // Non decoded longitude.
char flight[16]; // 8 chars flight number. char flight[16]; // 8 chars flight number.
int ew_dir; // 0 = East, 1 = West. int ew_velocity; // E/W velocity.
int ew_velocity; // E/W velocity. int ns_velocity; // N/S velocity.
int ns_dir; // 0 = North, 1 = South. int vert_rate; // Vertical rate.
int ns_velocity; // N/S velocity. int velocity; // Reported by aircraft, or computed from from EW and NS velocity
int vert_rate_source; // Vertical rate source.
int vert_rate_sign; // Vertical rate sign.
int vert_rate; // Vertical rate.
int velocity; // Reported by aircraft, or computed from from EW and NS velocity
int tasflag; // TAS or IAS
// DF4, DF5, DF20, DF21 // DF4, DF5, DF20, DF21
int fs; // Flight status for DF4,5,20,21 int fs; // Flight status for DF4,5,20,21
int dr; // Request extraction of downlink request. int dr; // Request extraction of downlink request.
int um; // Request extraction of downlink request. int um; // Request extraction of downlink request.
int modeA; // 13 bits identity (Squawk). int modeA; // 13 bits identity (Squawk).
// Fields used by multiple message types. // Fields used by multiple message types.
int altitude; int altitude;
@ -1048,7 +1048,8 @@ void decodeModeAMessage(struct modesMessage *mm, int ModeA)
mm->addr = 0x00FF0000 | (ModeA & 0x0000FF7F); mm->addr = 0x00FF0000 | (ModeA & 0x0000FF7F);
// Set the Identity field to ModeA // Set the Identity field to ModeA
mm->modeA = ModeA & 0x7777; mm->modeA = ModeA & 0x7777;
mm->bFlags |= MODES_ACFLAGS_SQUAWK_VALID;
// Flag ident in flight status // Flag ident in flight status
mm->fs = ModeA & 0x0080; mm->fs = ModeA & 0x0080;
@ -1465,7 +1466,11 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
// Fields for DF5, DF21 = Gillham encoded Squawk // Fields for DF5, DF21 = Gillham encoded Squawk
if (mm->msgtype == 5 || mm->msgtype == 21) { if (mm->msgtype == 5 || mm->msgtype == 21) {
mm->modeA = decodeID13Field((msg[2] << 8) | msg[3]); int ID13Field = ((msg[2] << 8) | msg[3]) & 0x1FFF;
if (ID13Field) {
mm->bFlags |= MODES_ACFLAGS_SQUAWK_VALID;
mm->modeA = decodeID13Field(ID13Field);
}
} }
// Fields for DF0, DF4, DF16, DF20 13 bit altitude // Fields for DF0, DF4, DF16, DF20 13 bit altitude
@ -1473,19 +1478,21 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
mm->msgtype == 16 || mm->msgtype == 20) { mm->msgtype == 16 || mm->msgtype == 20) {
int AC13Field = ((msg[2] << 8) | msg[3]) & 0x1FFF; int AC13Field = ((msg[2] << 8) | msg[3]) & 0x1FFF;
if (AC13Field) { // Only attempt to decode if a valid (non zero) altitude is present if (AC13Field) { // Only attempt to decode if a valid (non zero) altitude is present
mm->bFlags |= MODES_ACFLAGS_ALTITUDE_VALID;
mm->altitude = decodeAC13Field(AC13Field, &mm->unit); mm->altitude = decodeAC13Field(AC13Field, &mm->unit);
} }
} }
// Fields for DF17 squitter // Fields for DF17 squitter
if (mm->msgtype == 17) { if (mm->msgtype == 17) {
mm->metype = msg[4] >> 3; // Extended squitter message type int metype = mm->metype = msg[4] >> 3; // Extended squitter message type
mm->mesub = msg[4] & 7; // Extended squitter message subtype int mesub = mm->mesub = msg[4] & 7; // Extended squitter message subtype
// Decode the extended squitter message // Decode the extended squitter message
if (mm->metype >= 1 && mm->metype <= 4) { // Aircraft Identification and Category if (metype >= 1 && metype <= 4) { // Aircraft Identification and Category
uint32_t chars; uint32_t chars;
mm->bFlags |= MODES_ACFLAGS_CALLSIGN_VALID;
chars = (msg[5] << 16) | (msg[6] << 8) | (msg[7]); chars = (msg[5] << 16) | (msg[6] << 8) | (msg[7]);
mm->flight[3] = ais_charset[chars & 0x3F]; chars = chars >> 6; mm->flight[3] = ais_charset[chars & 0x3F]; chars = chars >> 6;
@ -1501,65 +1508,70 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
mm->flight[8] = '\0'; mm->flight[8] = '\0';
} else if (mm->metype >= 5 && mm->metype <= 18) { // Position Message } else if (metype >= 5 && metype <= 18) { // Position Message
mm->fflag = msg[6] & (1<<2);
mm->tflag = msg[6] & (1<<3);
mm->raw_latitude = ((msg[6] & 3) << 15) | (msg[7] << 7) | (msg[8] >> 1); mm->raw_latitude = ((msg[6] & 3) << 15) | (msg[7] << 7) | (msg[8] >> 1);
mm->raw_longitude = ((msg[8] & 1) << 16) | (msg[9] << 8) | (msg[10]); mm->raw_longitude = ((msg[8] & 1) << 16) | (msg[9] << 8) | (msg[10]);
if (mm->metype >= 9) { // Airborne if (metype >= 9) { // Airborne
int AC12Field = ((msg[5] << 4) | (msg[6] >> 4)) & 0x0FFF; int AC12Field = ((msg[5] << 4) | (msg[6] >> 4)) & 0x0FFF;
if (AC12Field) {// Only attempt to decode if a valid (non zero) altitude is present if (AC12Field) {// Only attempt to decode if a valid (non zero) altitude is present
{mm->altitude = decodeAC12Field(AC12Field, &mm->unit);} mm->bFlags |= MODES_ACFLAGS_ALTITUDE_VALID;
mm->altitude = decodeAC12Field(AC12Field, &mm->unit);
} }
} else { // Ground } else { // Ground
int movement = ((msg[4] << 4) | (msg[5] >> 4)) & 0x007F; int movement = ((msg[4] << 4) | (msg[5] >> 4)) & 0x007F;
if ((movement) && (movement < 125)) mm->bFlags |= MODES_ACFLAGS_AOG;
{mm->velocity = decodeMovementField(movement);} if ((movement) && (movement < 125)) {
mm->bFlags |= MODES_ACFLAGS_SPEED_VALID;
mm->velocity = decodeMovementField(movement);
}
mm->heading_is_valid = (msg[5] & 0x08); if (msg[5] & 0x08) {
if (mm->heading_is_valid) { mm->bFlags |= MODES_ACFLAGS_HEADING_VALID;
mm->heading = ((((msg[5] << 4) | (msg[6] >> 4)) & 0x007F) * 45) >> 4; mm->heading = ((((msg[5] << 4) | (msg[6] >> 4)) & 0x007F) * 45) >> 4;
} }
} }
} else if (mm->metype == 19) { // Airborne Velocity Message } else if (metype == 19) { // Airborne Velocity Message
if ( (mm->mesub >= 1) && (mm->mesub <= 4) ) { if ( (mesub >= 1) && (mesub <= 4) ) {
int vert_rate = ((msg[8] & 0x07) << 6) | (msg[9] >> 2); int vert_rate = ((msg[8] & 0x07) << 6) | (msg[9] >> 2);
if (vert_rate) { if (vert_rate) {
mm->vert_rate_source = (msg[8] & 0x10) >> 4; --vert_rate;
mm->vert_rate_sign = (msg[8] & 0x08) >> 3; if (msg[8] & 0x08)
mm->vert_rate = vert_rate - 1; {vert_rate = 0 - vert_rate;}
mm->vert_rate = vert_rate * 64;
mm->bFlags |= MODES_ACFLAGS_VERTRATE_VALID;
} }
} }
if ((mm->mesub == 1) || (mm->mesub == 2)) { if ((mesub == 1) || (mesub == 2)) {
int ew_raw = ((msg[5] & 0x03) << 8) | msg[6]; int ew_raw = ((msg[5] & 0x03) << 8) | msg[6];
int ew_vel = ew_raw - 1; int ew_vel = ew_raw - 1;
int ns_raw = ((msg[7] & 0x7F) << 3) | (msg[8] >> 5); int ns_raw = ((msg[7] & 0x7F) << 3) | (msg[8] >> 5);
int ns_vel = ew_raw - 1; int ns_vel = ew_raw - 1;
if (mm->mesub == 2) { // If (supersonic) unit is 4 kts if (mesub == 2) { // If (supersonic) unit is 4 kts
ns_vel = ns_vel << 2; ns_vel = ns_vel << 2;
ew_vel = ew_vel << 2; ew_vel = ew_vel << 2;
} }
if (ew_raw) { // Do East/West if (ew_raw) { // Do East/West
mm->ew_velocity = ew_vel; mm->bFlags |= MODES_ACFLAGS_EWSPEED_VALID;
mm->ew_dir = (msg[5] & 0x04) >> 2; if (msg[5] & 0x04)
if (mm->ew_dir)
{ew_vel = 0 - ew_vel;} {ew_vel = 0 - ew_vel;}
mm->ew_velocity = ew_vel;
} }
if (ns_raw) { // Do North/South if (ns_raw) { // Do North/South
mm->ns_velocity = ns_vel; mm->bFlags |= MODES_ACFLAGS_NSSPEED_VALID;
mm->ns_dir = (msg[7] & 0x80) >> 7; if (msg[7] & 0x80)
if (mm->ns_dir)
{ns_vel = 0 - ns_vel;} {ns_vel = 0 - ns_vel;}
mm->ns_velocity = ns_vel;
} }
if (ew_raw && ns_raw) { if (ew_raw && ns_raw) {
// Compute velocity and angle from the two speed components // Compute velocity and angle from the two speed components
mm->bFlags |= (MODES_ACFLAGS_SPEED_VALID | MODES_ACFLAGS_HEADING_VALID);
mm->velocity = (int) sqrt((ns_vel * ns_vel) + (ew_vel * ew_vel)); mm->velocity = (int) sqrt((ns_vel * ns_vel) + (ew_vel * ew_vel));
if (mm->velocity) { if (mm->velocity) {
@ -1569,19 +1581,19 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
} }
} }
} else if (mm->mesub == 3 || mm->mesub == 4) { } else if (mesub == 3 || mesub == 4) {
int airspeed = ((msg[7] & 0x7f) << 3) | (msg[8] >> 5); int airspeed = ((msg[7] & 0x7f) << 3) | (msg[8] >> 5);
if (airspeed) { if (airspeed) {
mm->bFlags |= MODES_ACFLAGS_SPEED_VALID;
--airspeed; --airspeed;
if (mm->mesub == 4) // If (supersonic) unit is 4 kts if (mesub == 4) // If (supersonic) unit is 4 kts
{airspeed = airspeed << 2;} {airspeed = airspeed << 2;}
mm->velocity = airspeed; mm->velocity = airspeed;
mm->tasflag = (msg[7] & 0x80);
} }
mm->heading_is_valid = msg[5] & 0x04; if (msg[5] & 0x04) {
if (mm->heading_is_valid) { mm->bFlags |= MODES_ACFLAGS_HEADING_VALID;
mm->heading = ((((msg[5] & 0x03) << 8) | msg[6]) * 45) >> 7; mm->heading = ((((msg[5] & 0x03) << 8) | msg[6]) * 45) >> 7;
} }
} }
} }
@ -1592,6 +1604,7 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
if (msg[4] == 0x20) { // Aircraft Identification if (msg[4] == 0x20) { // Aircraft Identification
uint32_t chars; uint32_t chars;
mm->bFlags |= MODES_ACFLAGS_CALLSIGN_VALID;
chars = (msg[5] << 16) | (msg[6] << 8) | (msg[7]); chars = (msg[5] << 16) | (msg[6] << 8) | (msg[7]);
mm->flight[3] = ais_charset[chars & 0x3F]; chars = chars >> 6; mm->flight[3] = ais_charset[chars & 0x3F]; chars = chars >> 6;
@ -1720,25 +1733,30 @@ void displayModesMessage(struct modesMessage *mm) {
//} else if (mm->metype >= 5 && mm->metype <= 8) { // Surface position //} else if (mm->metype >= 5 && mm->metype <= 8) { // Surface position
} else if (mm->metype >= 9 && mm->metype <= 18) { // Airborne position Baro } else if (mm->metype >= 9 && mm->metype <= 18) { // Airborne position Baro
printf(" F flag : %s\n", mm->fflag ? "odd" : "even"); printf(" F flag : %s\n", (mm->msg[6] & 0x04) ? "odd" : "even");
printf(" T flag : %s\n", mm->tflag ? "UTC" : "non-UTC"); printf(" T flag : %s\n", (mm->msg[6] & 0x08) ? "UTC" : "non-UTC");
printf(" Altitude : %d feet\n", mm->altitude); printf(" Altitude : %d feet\n", mm->altitude);
printf(" Latitude : %d (not decoded)\n", mm->raw_latitude); printf(" Latitude : %d (not decoded)\n", mm->raw_latitude);
printf(" Longitude: %d (not decoded)\n", mm->raw_longitude); printf(" Longitude: %d (not decoded)\n", mm->raw_longitude);
} else if (mm->metype == 19) { // Airborne Velocity } else if (mm->metype == 19) { // Airborne Velocity
if (mm->mesub == 1 || mm->mesub == 2) { if (mm->mesub == 1 || mm->mesub == 2) {
printf(" EW direction : %d\n", mm->ew_dir); printf(" EW status : %s\n", (mm->bFlags & MODES_ACFLAGS_EWSPEED_VALID) ? "Valid" : "Unavailable");
printf(" EW velocity : %d\n", mm->ew_velocity); printf(" EW velocity : %d\n", mm->ew_velocity);
printf(" NS direction : %d\n", mm->ns_dir); printf(" NS status : %s\n", (mm->bFlags & MODES_ACFLAGS_NSSPEED_VALID) ? "Valid" : "Unavailable");
printf(" NS velocity : %d\n", mm->ns_velocity); printf(" NS velocity : %d\n", mm->ns_velocity);
printf(" Vertical rate src : %d\n", mm->vert_rate_source); printf(" Vertical status : %s\n", (mm->bFlags & MODES_ACFLAGS_VERTRATE_VALID) ? "Valid" : "Unavailable");
printf(" Vertical rate sign: %d\n", mm->vert_rate_sign); printf(" Vertical rate src : %d\n", ((mm->msg[8] >> 4) & 1));
printf(" Vertical rate : %d\n", mm->vert_rate); printf(" Vertical rate : %d\n", mm->vert_rate);
} else if (mm->mesub == 3 || mm->mesub == 4) { } else if (mm->mesub == 3 || mm->mesub == 4) {
printf(" Heading status: %d", mm->heading_is_valid); printf(" Heading status : %s\n", (mm->bFlags & MODES_ACFLAGS_HEADING_VALID) ? "Valid" : "Unavailable");
printf(" Heading: %d", mm->heading); printf(" Heading : %d\n", mm->heading);
printf(" Airspeed status : %s\n", (mm->bFlags & MODES_ACFLAGS_SPEED_VALID) ? "Valid" : "Unavailable");
printf(" Airspeed : %d\n", mm->velocity);
printf(" Vertical status : %s\n", (mm->bFlags & MODES_ACFLAGS_VERTRATE_VALID) ? "Valid" : "Unavailable");
printf(" Vertical rate src : %d\n", ((mm->msg[8] >> 4) & 1));
printf(" Vertical rate : %d\n", mm->vert_rate);
} else { } else {
printf(" Unrecognized ME subtype: %d subtype: %d\n", mm->metype, mm->mesub); printf(" Unrecognized ME subtype: %d subtype: %d\n", mm->metype, mm->mesub);
@ -2482,11 +2500,12 @@ void decodeCPR(struct aircraft *a, int fflag, int surface) {
* Note: text of document describes trunc() functionality for deltaZI calculation * Note: text of document describes trunc() functionality for deltaZI calculation
* but the formulae use floor(). * but the formulae use floor().
*/ */
int decodeCPRrelative(struct aircraft *a, int fflag, int surface, double latr, double lonr) { int decodeCPRrelative(struct aircraft *a, int fflag, int surface) {
double AirDlat; double AirDlat;
double AirDlon; double AirDlon;
double lat; double lat;
double lon; double lon;
double lonr, latr;
double rlon, rlat; double rlon, rlat;
int j,m; int j,m;
@ -2613,18 +2632,31 @@ struct aircraft *interactiveReceiveData(struct modesMessage *mm) {
if (mm->metype >= 1 && mm->metype <= 4) { if (mm->metype >= 1 && mm->metype <= 4) {
memcpy(a->flight, mm->flight, sizeof(a->flight)); memcpy(a->flight, mm->flight, sizeof(a->flight));
} else if (mm->metype >= 9 && mm->metype <= 18) { } else if (mm->metype >= 5 && mm->metype <= 18) {
if ( (a->modeCcount) // if we've a modeCcount already int fflag = mm->msg[6] & 0x04;
&& (a->altitude != mm->altitude ) ) // and Altitude has changed
// && (a->modeC != mm->modeC + 1) // and Altitude not changed by +100 feet if ((a->bFlags ^ mm->bFlags) & MODES_ACFLAGS_AOG) {
// && (a->modeC + 1 != mm->modeC ) ) // and Altitude not changes by -100 feet a->odd_cprtime = a->even_cprtime = 0; // Change airborne = change CPR scale need new pair
{ a->bFlags ^= MODES_ACFLAGS_AOG; // Ground = metype 5-8, Airborne = metype 9-18
a->modeCcount = 0; //....zero the hit count }
a->modeACflags &= ~MODEAC_MSG_MODEC_HIT;
} if (mm->metype >= 9) { // Airborne
a->altitude = mm->altitude; if ( (a->modeCcount) // if we've a modeCcount already
a->modeC = (mm->altitude + 49) / 100; && (a->altitude != mm->altitude ) ) // and Altitude has changed
if (mm->fflag) { // && (a->modeC != mm->modeC + 1) // and Altitude not changed by +100 feet
// && (a->modeC + 1 != mm->modeC ) ) // and Altitude not changes by -100 feet
{
a->modeCcount = 0; //....zero the hit count
a->modeACflags &= ~MODEAC_MSG_MODEC_HIT;
}
a->altitude = mm->altitude;
a->modeC = (mm->altitude + 49) / 100;
} else { // Ground
a->speed = mm->velocity;
a->track = mm->heading;
}
if (fflag) {
a->odd_cprlat = mm->raw_latitude; a->odd_cprlat = mm->raw_latitude;
a->odd_cprlon = mm->raw_longitude; a->odd_cprlon = mm->raw_longitude;
a->odd_cprtime = mstime(); a->odd_cprtime = mstime();
@ -2634,16 +2666,16 @@ struct aircraft *interactiveReceiveData(struct modesMessage *mm) {
a->even_cprtime = mstime(); a->even_cprtime = mstime();
} }
// Try relative CPR first // Try relative CPR first
if (decodeCPRrelative(a, mm->fflag, 0, 0, 0)) { if (decodeCPRrelative(a, fflag, (mm->bFlags & MODES_ACFLAGS_AOG))) {
// If it fails then try global if the two data are less than 10 seconds apart, compute // If it fails then try global if the two data are less than 10 seconds apart, compute
// the position. // the position.
if (abs((int)(a->even_cprtime - a->odd_cprtime)) <= 10000) { if (abs((int)(a->even_cprtime - a->odd_cprtime)) <= 10000) {
decodeCPR(a, mm->fflag, 0); decodeCPR(a, fflag, (mm->bFlags & MODES_ACFLAGS_AOG));
} }
} }
} else if (mm->metype == 19) { } else if (mm->metype == 19) {
if (mm->mesub == 1 || mm->mesub == 2) { if ((mm->mesub >= 1) && (mm->mesub <= 4)) {
a->speed = mm->velocity; a->speed = mm->velocity;
a->track = mm->heading; a->track = mm->heading;
} }