The NL function uses the precomputed table from 1090-WP-9-14 */

This is a wrapper for dumpMagnitudeVector() that also show the message * in hex format with an additional description. * * descr is the additional

Always positive MOD operation, used for CPR decoding. */

Scale a sample value by a fixed-point factor, clamping to avoid overflow. * The scale is in 16384ths (so 16384 = 1.0, 32768 = 2.0, etc). */

Compute the CRC syndrome of a Mode S message. * * This function computes the CRC of the data portion (excluding the last * 24 bits which are the tr

On error free the client, collect the structure, adjust maxfd if needed. */

Given the Downlink Format (DF) of the message, return the message length * in bits. */

Returns 1 if the specified ICAO address was seen in a DF format with * proper checksum (not xored with address) no more than * MODES_ICAO_CACHE_TTL

Hash the ICAO address to index our cache of MODES_ICAO_CACHE_LEN * elements, that is assumed to be a power of two. */

This function is called a few times every second by main in order to * perform tasks we need to do continuously, like accepting new clients * from t

Decode a raw Mode S message demodulated as a stream of bytes by * detectModeS(), and split it into fields populating a modesMessage * structure. */

Decode ground speed from surface movement field. * Returns speed in knots, or -1 if speed is not available. */

Given a received message, compute its syndrome and look it up in the * precomputed table. If we find a match, we know the exact bit positions * that

Get the number of rows after the terminal changes size. */

Turn an hex digit into its 4 bit decimal value. * Returns -1 if the digit is not in the 0-F range. */

When in interactive mode If we don't receive new nessages within * MODES_INTERACTIVE_TTL seconds we remove the aircraft from the list. */

Show the currently captured interactive data on screen. */

Compute the CRC of a Mode S message (data portion only). * This returns just the CRC computed from the data bits, without XORing * with the transmit

This function polls the clients using read() in order to receive new * messages from the net. * * The message is supposed to be separated by the ne

Send the specified message to all clients listening for a given service. */

When a new message is available, because it was decoded from the * RTL device, file, or received in the TCP input port, or any other * way we can re

Add the specified entry to the cache of recently seen ICAO addresses. * Note that we also add a timestamp so that we can make sure that the * entry

Return a description of planes in json. */

Phase enhancement algorithm. * * This function estimates whether we are sampling early or late relative to * the signal phase, and by how much, by

If the message type has the checksum xored with the ICAO address, try to * brute force it using a list of recently seen ICAO addresses. * * Do this

Turn I/Q samples pointed by Modes.data into the magnitude vector * pointed by Modes.magnitude. */

Decode the 12 bit AC altitude field (in DF 17 and others). * Returns the altitude or 0 if it can't be decoded. */

Decode the 13 bit AC altitude field (in DF 20 and others). * Returns the altitude, and set 'unit' to either MODES_UNIT_METERS * or MDOES_UNIT_FEETS.

This algorithm comes from: * http://www.lll.lu/~edward/edward/adsb/DecodingADSBposition.html. * * * A few remarks: * 1) 131072 is 2^17 since CPR

Decode surface CPR position using local decoding with reference position. * * Surface position messages use a different CPR encoding than airborne:

Detect a Mode S messages inside the magnitude buffer pointed by 'm' and of * size 'mlen' bytes. Every detected Mode S message is convert it into a *

This function gets a decoded Mode S Message and prints it on the screen * in a human readable format. */

Helper function for dumpMagnitudeVector(). * It prints a single bar used to display raw signals. * * Since every magnitude sample is between 0-255,

Produce a raw representation of the message as a Javascript file * loadable by debug.html. */

Return a new aircraft structure for the interactive mode linked list * of aircrafts. */

Return the aircraft with the specified address, or NULL if no aircraft * exists with this address. */

Receive new messages and populate the interactive mode with more info. */

This function gets called from time to time when the decoding thread is * awakened by new data arriving. This usually happens a few times every * se

Compute the table of all syndromes for 1-bit and 2-bit error vectors. * We don't include the first 5 bits (the DF type field) since corrupting * tho

Networking "stack" initialization. */

Read data from clients. This function actually delegates a lower-level * function that depends on the kind of service (raw, http, ...). */

Write raw output to TCP clients. */

Write SBS output to TCP clients. */

This function is used when "net only" mode is enabled to know when there * is at least a new client to serve. Note that the dump1090 networking model

This is used when --ifile is specified in order to read data from file * instead of using an RTLSDR device. */

Get raw IQ samples and filter everything is < than the specified level * for more than 256 samples in order to reduce example file size. */

Like read(2) but make sure 'count' is read before to return * (unless error or EOF condition is encountered) */

Like write(2) but make sure 'count' is read before to return * (unless error is encountered) */

Comparison function for qsort/bsearch on errorinfo by syndrome. */

This function decodes a string representing a Mode S message in * raw hex format like: *8D4B969699155600E87406F5B69F; * The string is supposed to be

Get an HTTP request header and write the response to the client. * Again here we assume that the socket buffer is enough without doing * any kind of

We read data using a thread, so the main thread only handles decoding * without caring about data acquisition. */

We use a thread reading data in background, while the main thread * handles decoding and visualization of data to the user. * * The reading thread

Handle resizing terminal. */