gps_qemu.c

Android平台上Midware层源代码合集

#include <errno.h>
#include <pthread.h>
#include <termios.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <math.h>
#include <time.h>

#define  LOG_TAG  "gps_qemu"
#include <cutils/log.h>
#include <cutils/sockets.h>
#include <cutils/properties.h>
#include <hardware/gps.h>

/* the name of the qemud-controlled socket */
#define  QEMUD_SOCKET_NAME  "qemud_gps"

#define  GPS_DEBUG  0

#if GPS_DEBUG
#  define  D(...)   LOGD(__VA_ARGS__)
#else
#  define  D(...)   ((void)0)
#endif


/*****************************************************************/
/*****************************************************************/
/*****                                                       *****/
/*****       N M E A   T O K E N I Z E R                     *****/
/*****                                                       *****/
/*****************************************************************/
/*****************************************************************/

typedef struct {
    const char*  p;
    const char*  end;
} Token;

#define  MAX_NMEA_TOKENS  16

typedef struct {
    int     count;
    Token   tokens[ MAX_NMEA_TOKENS ];
} NmeaTokenizer;

static int
nmea_tokenizer_init( NmeaTokenizer*  t, const char*  p, const char*  end )
{
    int    count = 0;
    char*  q;

    // the initial '$' is optional
    if (p < end && p[0] == '$')
        p += 1;

    // remove trailing newline
    if (end > p && end[-1] == '\n') {
        end -= 1;
        if (end > p && end[-1] == '\r')
            end -= 1;
    }

    // get rid of checksum at the end of the sentecne
    if (end >= p+3 && end[-3] == '*') {
        end -= 3;
    }

    while (p < end) {
        const char*  q = p;

        q = memchr(p, ',', end-p);
        if (q == NULL)
            q = end;

        if (q > p) {
            if (count < MAX_NMEA_TOKENS) {
                t->tokens[count].p   = p;
                t->tokens[count].end = q;
                count += 1;
            }
        }
        if (q < end)
            q += 1;

        p = q;
    }

    t->count = count;
    return count;
}

static Token
nmea_tokenizer_get( NmeaTokenizer*  t, int  index )
{
    Token  tok;
    static const char*  dummy = "";

    if (index < 0 || index >= t->count) {
        tok.p = tok.end = dummy;
    } else
        tok = t->tokens[index];

    return tok;
}


static int
str2int( const char*  p, const char*  end )
{
    int   result = 0;
    int   len    = end - p;

    for ( ; len > 0; len--, p++ )
    {
        int  c;

        if (p >= end)
            goto Fail;

        c = *p - '0';
        if ((unsigned)c >= 10)
            goto Fail;

        result = result*10 + c;
    }
    return  result;

Fail:
    return -1;
}

static double
str2float( const char*  p, const char*  end )
{
    int   result = 0;
    int   len    = end - p;
    char  temp[16];

    if (len >= (int)sizeof(temp))
        return 0.;

    memcpy( temp, p, len );
    temp[len] = 0;
    return strtod( temp, NULL );
}

/*****************************************************************/
/*****************************************************************/
/*****                                                       *****/
/*****       N M E A   P A R S E R                           *****/
/*****                                                       *****/
/*****************************************************************/
/*****************************************************************/

#define  NMEA_MAX_SIZE  83

typedef struct {
    int     pos;
    int     overflow;
    int     utc_year;
    int     utc_mon;
    int     utc_day;
    int     utc_diff;
    GpsLocation  fix;
    gps_location_callback  callback;
    char    in[ NMEA_MAX_SIZE+1 ];
} NmeaReader;


static void
nmea_reader_update_utc_diff( NmeaReader*  r )
{
    time_t         now = time(NULL);
    struct tm      tm_local;
    struct tm      tm_utc;
    long           time_local, time_utc;

    gmtime_r( &now, &tm_utc );
    localtime_r( &now, &tm_local );

    time_local = tm_local.tm_sec +
                 60*(tm_local.tm_min +
                 60*(tm_local.tm_hour +
                 24*(tm_local.tm_yday +
                 365*tm_local.tm_year)));

    time_utc = tm_utc.tm_sec +
               60*(tm_utc.tm_min +
               60*(tm_utc.tm_hour +
               24*(tm_utc.tm_yday +
               365*tm_utc.tm_year)));

    r->utc_diff = time_utc - time_local;
}


static void
nmea_reader_init( NmeaReader*  r )
{
    memset( r, 0, sizeof(*r) );

    r->pos      = 0;
    r->overflow = 0;
    r->utc_year = -1;
    r->utc_mon  = -1;
    r->utc_day  = -1;
    r->callback = NULL;

    nmea_reader_update_utc_diff( r );
}


static void
nmea_reader_set_callback( NmeaReader*  r, gps_location_callback  cb )
{
    r->callback = cb;
    if (cb != NULL && r->fix.flags != 0) {
        D("%s: sending latest fix to new callback", __FUNCTION__);
        r->callback( &r->fix );
        r->fix.flags = 0;
    }
}


static int
nmea_reader_update_time( NmeaReader*  r, Token  tok )
{
    int        hour, minute;
    double     seconds;
    struct tm  tm;
    time_t     fix_time;

    if (tok.p + 6 > tok.end)
        return -1;

    if (r->utc_year < 0) {
        // no date yet, get current one
        time_t  now = time(NULL);
        gmtime_r( &now, &tm );
        r->utc_year = tm.tm_year + 1900;
        r->utc_mon  = tm.tm_mon + 1;
        r->utc_day  = tm.tm_mday;
    }

    hour    = str2int(tok.p,   tok.p+2);
    minute  = str2int(tok.p+2, tok.p+4);
    seconds = str2float(tok.p+4, tok.end);

    tm.tm_hour = hour;
    tm.tm_min  = minute;
    tm.tm_sec  = (int) seconds;
    tm.tm_year = r->utc_year - 1900;
    tm.tm_mon  = r->utc_mon - 1;
    tm.tm_mday = r->utc_day;

    fix_time = mktime( &tm ) + r->utc_diff;
    r->fix.timestamp = (long long)fix_time * 1000;
    return 0;
}

static int
nmea_reader_update_date( NmeaReader*  r, Token  date, Token  time )
{
    Token  tok = date;
    int    day, mon, year;

    if (tok.p + 6 != tok.end) {
        D("date not properly formatted: '%.*s'", tok.end-tok.p, tok.p);
        return -1;
    }
    day  = str2int(tok.p, tok.p+2);
    mon  = str2int(tok.p+2, tok.p+4);
    year = str2int(tok.p+4, tok.p+6) + 2000;

    if ((day|mon|year) < 0) {
        D("date not properly formatted: '%.*s'", tok.end-tok.p, tok.p);
        return -1;
    }

    r->utc_year  = year;
    r->utc_mon   = mon;
    r->utc_day   = day;

    return nmea_reader_update_time( r, time );
}


static double
convert_from_hhmm( Token  tok )
{
    double  val     = str2float(tok.p, tok.end);
    int     degrees = (int)(floor(val) / 100);
    double  minutes = val - degrees*100.;
    double  dcoord  = degrees + minutes / 60.0;
    return dcoord;
}


static int
nmea_reader_update_latlong( NmeaReader*  r,
                            Token        latitude,
                            char         latitudeHemi,
                            Token        longitude,
                            char         longitudeHemi )
{
    double   lat, lon;
    Token    tok;

    tok = latitude;
    if (tok.p + 6 > tok.end) {
        D("latitude is too short: '%.*s'", tok.end-tok.p, tok.p);
        return -1;
    }
    lat = convert_from_hhmm(tok);
    if (latitudeHemi == 'S')
        lat = -lat;

    tok = longitude;
    if (tok.p + 6 > tok.end) {
        D("longitude is too short: '%.*s'", tok.end-tok.p, tok.p);
        return -1;
    }
    lon = convert_from_hhmm(tok);
    if (longitudeHemi == 'W')
        lon = -lon;

    r->fix.flags    |= GPS_LOCATION_HAS_LAT_LONG;
    r->fix.latitude  = lat;
    r->fix.longitude = lon;
    return 0;
}


static int
nmea_reader_update_altitude( NmeaReader*  r,
                             Token        altitude,
                             Token        units )
{
    double  alt;
    Token   tok = altitude;

    if (tok.p >= tok.end)
        return -1;

    r->fix.flags   |= GPS_LOCATION_HAS_ALTITUDE;
    r->fix.altitude = str2float(tok.p, tok.end);
    return 0;
}


static int
nmea_reader_update_bearing( NmeaReader*  r,
                            Token        bearing )
{
    double  alt;
    Token   tok = bearing;

    if (tok.p >= tok.end)
        return -1;

    r->fix.flags   |= GPS_LOCATION_HAS_BEARING;
    r->fix.bearing  = str2float(tok.p, tok.end);
    return 0;
}


static int
nmea_reader_update_speed( NmeaReader*  r,
                          Token        speed )
{
    double  alt;
    Token   tok = speed;

    if (tok.p >= tok.end)
        return -1;

    r->fix.flags   |= GPS_LOCATION_HAS_SPEED;
    r->fix.speed    = str2float(tok.p, tok.end);
    return 0;
}


static void
nmea_reader_parse( NmeaReader*  r )
{
   /* we received a complete sentence, now parse it to generate
    * a new GPS fix...
    */
    NmeaTokenizer  tzer[1];
    Token          tok;

    D("Received: '%.*s'", r->pos, r->in);
    if (r->pos < 9) {
        D("Too short. discarded.");
        return;
    }

    nmea_tokenizer_init(tzer, r->in, r->in + r->pos);
#if GPS_DEBUG
    {
        int  n;
        D("Found %d tokens", tzer->count);
        for (n = 0; n < tzer->count; n++) {
            Token  tok = nmea_tokenizer_get(tzer,n);
            D("%2d: '%.*s'", n, tok.end-tok.p, tok.p);
        }
    }
#endif

    tok = nmea_tokenizer_get(tzer, 0);
    if (tok.p + 5 > tok.end) {
        D("sentence id '%.*s' too short, ignored.", tok.end-tok.p, tok.p);
        return;
    }

    // ignore first two characters.
    tok.p += 2;
    if ( !memcmp(tok.p, "GGA", 3) ) {
        // GPS fix
        Token  tok_time          = nmea_tokenizer_get(tzer,1);
        Token  tok_latitude      = nmea_tokenizer_get(tzer,2);
        Token  tok_latitudeHemi  = nmea_tokenizer_get(tzer,3);
        Token  tok_longitude     = nmea_tokenizer_get(tzer,4);
        Token  tok_longitudeHemi = nmea_tokenizer_get(tzer,5);
        Token  tok_altitude      = nmea_tokenizer_get(tzer,9);
        Token  tok_altitudeUnits = nmea_tokenizer_get(tzer,10);

        nmea_reader_update_time(r, tok_time);
        nmea_reader_update_latlong(r, tok_latitude,
                                      tok_latitudeHemi.p[0],
                                      tok_longitude,
                                      tok_longitudeHemi.p[0]);
        nmea_reader_update_altitude(r, tok_altitude, tok_altitudeUnits);

    } else if ( !memcmp(tok.p, "GSA", 3) ) {
        // do something ?
    } else if ( !memcmp(tok.p, "RMC", 3) ) {
        Token  tok_time          = nmea_tokenizer_get(tzer,1);
        Token  tok_fixStatus     = nmea_tokenizer_get(tzer,2);
        Token  tok_latitude      = nmea_tokenizer_get(tzer,3);
        Token  tok_latitudeHemi  = nmea_tokenizer_get(tzer,4);
        Token  tok_longitude     = nmea_tokenizer_get(tzer,5);
        Token  tok_longitudeHemi = nmea_tokenizer_get(tzer,6);
        Token  tok_speed         = nmea_tokenizer_get(tzer,7);
        Token  tok_bearing       = nmea_tokenizer_get(tzer,8);
        Token  tok_date          = nmea_tokenizer_get(tzer,9);

        D("in RMC, fixStatus=%c", tok_fixStatus.p[0]);
        if (tok_fixStatus.p[0] == 'A')
        {
            nmea_reader_update_date( r, tok_date, tok_time );

            nmea_reader_update_latlong( r, tok_latitude,
                                           tok_latitudeHemi.p[0],
                                           tok_longitude,
                                           tok_longitudeHemi.p[0] );

            nmea_reader_update_bearing( r, tok_bearing );
            nmea_reader_update_speed  ( r, tok_speed );
        }
    } else {
        tok.p -= 2;
        D("unknown sentence '%.*s", tok.end-tok.p, tok.p);
    }
    if (r->fix.flags != 0) {
#if GPS_DEBUG
        char   temp[256];
        char*  p   = temp;
        char*  end = p + sizeof(temp);
        struct tm   utc;