北斗gps Android hal层so库代码

网上下载的代码，自己编辑修改，加入了北斗定位功能，主要是修改了GSV，GSA语句的解析，在A10平台上测试良好：

北斗双模下的LOG：

$GPGSV,3,3,10,31,46,012,,32,39,287,40*79
$BDGSV,1,1,04,02,45,242,43,03,00,000,34,06,00,000,32,09,38,216,37*6C
$GNRMC,040059.080,A,2230.8804,N,11354.9920,E,0.83,0.00,040613,,,A*7C
$GNVTG,0.00,T,,M,0.83,N,1.54,K,A*28
$GNZDA,040059.080,04,06,2013,00,00*4A
$GNGGA,040100.000,2230.8897,N,11355.0128,E,1,06,28.3,79.2,M,0.0,M,,*71
$GNGLL,2230.8897,N,11355.0128,E,040100.000,A,0*36
$GPGSA,A,3,16,20,06,32,,,,,,,,,30.4,28.3,11.2*0C
$BDGSA,A,3,02,09,,,,,,,,,,,30.4,28.3,11.2*14
$GPGSV,3,1,10,03,06,197,,06,19,182,33,14,50,109,,16,48,230,46*75
$GPGSV,3,2,10,20,16,305,41,22,15,171,,29,23,066,22,30,00,000,25*72
$GPGSV,3,3,10,31,46,012,,32,39,287,40*79
$BDGSV,1,1,04,02,45,242,43,03,00,000,34,06,00,000,32,09,38,216,37*6C
$GNRMC,040100.000,A,2230.8897,N,11355.0128,E,0.64,0.00,040613,,,A*72
$GNVTG,0.00,T,,M,0.64,N,1.19,K,A*28
$GNZDA,040100.000,04,06,2013,00,00*4F

一些命令的解释：

$GNRMC,091356.000,V,2230.8777,N,11354.9659,E,7.88,270.95,040613,,,N*63
|
这里V变成A时候表示定位成功
$GPGSV,3,1,11,01,46,169,,03,29,038,,06,13,045,,07,55,322,*74
$GPGSV,3,2,11,08,24,325,,11,72,159,,13,32,226,,16,17,081,*77
$GPGSV,3,3,11,19,49,022,,23,20,200,,28,07,296,*4D
$BDGSV,1,1,04,02,44,240,,07,64,173,,08,60,343,,10,77,244,*61
GPGSV表示GPS的GSV，BDGSV表示北斗的GSV
第一列3表示有3行GPGSV语句输出；紧接着第二列的1、2、3表示当前是第几行GSV；接着的11表示一共11颗星，接着的是4个数字为一组的信号值

$GPGSA,A,3,16,20,06,32,,,,,,,,,30.4,28.3,11.2*0C
$BDGSA,A,3,02,09,,,,,,,,,,,30.4,28.3,11.2*14

这里第3～14位，一共12位表示已经定位的卫星号，它们和GSV中可见卫星信息组中的卫星号一致，上层要判断这两个数值一致才表示可用卫星，可见

GSV中得到的是可见卫星数量，GSA中得到的是可用卫星数量，可见卫星数量>=可用卫星数量，他们就是GPS测试软件中的in view和in use数值

北斗的一些发送命令：

    char *str_B115200 = "$PCAS01,5*19\r\n";
    char *str_B9600 = "$PCAS01,1*1D\r\n";
    char *str_save = "$PCAS00*01\r\n";//将当前配置写入flash,否则断电后恢复为默认的
    char *str_beidou    = "$PCAS04,2*1B\r\n"; //北斗模式
    char *str_shuangmo = "$PCAS04,3*1A\r\n"; //北斗和GPS共存模式
这里的*后面的数字是异或校验，如$PCAS01,5*19这一行，'P' ^ 'C' ^ 'A' ^ 'S'^ '0' ^ '1' ^ ',' ^ '5' == 0x19；

详细的命令参考厂商的手册

下面是源代码：

Android.mk

LOCAL_PATH := $(call my-dir)#ifneq ($(TARGET_PRODUCT),sim)
# HAL module implemenation, not prelinked and stored in
# hw/<GPS_HARDWARE_MODULE_ID>.<ro.hardware>.so
include $(CLEAR_VARS)
LOCAL_PRELINK_MODULE := false
LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)/hw
LOCAL_CFLAGS += -DQEMU_HARDWARE
LOCAL_SHARED_LIBRARIES := liblog libcutils libhardware
LOCAL_SRC_FILES := gps.c
LOCAL_MODULE := gps.default
LOCAL_MODULE_TAGS := optional
include $(BUILD_SHARED_LIBRARY)
#endif

gps.c:

/** Copyright (C) 2010 The Android Open Source Project** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**      http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*//* this implements a GPS hardware library for the Android emulator.* the following code should be built as a shared library that will be* placed into /system/lib/hw/gps.goldfish.so** it will be loaded by the code in hardware/libhardware/hardware.c* which is itself called from android_location_GpsLocationProvider.cpp*/#include <errno.h>
#include <pthread.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <math.h>
#include <time.h>#include <stdio.h> /*????????*/#include <stdlib.h> /*???????*/#include <unistd.h> /*Unix ??????*/#include <sys/types.h> #include <sys/stat.h> #include <termios.h> /*PPSIX ??????*/#include <errno.h> /*?????*/#define  LOG_TAG  "gps_qemu"
#include <cutils/log.h>
#include <cutils/sockets.h>
#include <hardware/gps.h>
#include <hardware/qemud.h>
#include <hardware/hardware.h>
/* the name of the qemud-controlled socket */
#define  QEMU_CHANNEL_NAME  "gps"#define  GPS_DEBUG  0
#define Ublox_6M 1
#if GPS_DEBUG
#  define  D(...)   LOGE(__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  20typedef struct {int     count;Token   tokens[ MAX_NMEA_TOKENS ];
} NmeaTokenizer;/*********************************************************************/
GpsStatus g_status;static int
nmea_tokenizer_init( NmeaTokenizer*  t, const char*  p, const char*  end )
{int    count = 0;char*  q;// the initial '$' is optionalif (p < end && p[0] == '$')p += 1;// remove trailing newlineif (end > p && end[-1] == '\n') {end -= 1;if (end > p && end[-1] == '\r')end -= 1;}// get rid of checksum at the end of the sentecneif (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;} elsetok = 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  83typedef struct {int     pos;int     overflow;int     utc_year;int     utc_mon;int     utc_day;int     utc_diff;GpsLocation  fix;//********************************GpsSvStatus  sv_status;int     sv_status_changed;
#ifdef Ublox_6MGpsCallbacks callback;#else//*********************************gps_location_callback  callback;
#endifchar    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_local - time_utc;
}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;
#ifdef Ublox_6Mr->callback.sv_status_cb = NULL;//r->callback.nmea_cb = NULL;r->callback.location_cb = NULL;r->callback.status_cb = NULL;
#elser->callback = NULL;
#endifr->fix.size = sizeof(r->fix);nmea_reader_update_utc_diff( r );
}static void
nmea_reader_set_callback( NmeaReader*  r, gps_location_callback  cb )
{
#ifdef Ublox_6Mr->callback.location_cb  = cb;//
#elser->callback  = cb;
#endifif (cb != NULL && r->fix.flags != 0) {D("%s: sending latest fix to new callback", __FUNCTION__);
#ifdef Ublox_6Mr->callback.location_cb( &r->fix );/
#elser->fix.flags = 0;
#endif}
}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 onetime_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;tm.tm_isdst = -1;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 int nmea_reader_update_accuracy(NmeaReader * r,  Token accuracy)
{double acc;Token  tok = accuracy;if(tok.p >= tok.end)return -1;r->fix.accuracy = str2float(tok.p, tok.end);if(r->fix.accuracy == 99.99){return 0;}r->fix.flags |= GPS_LOCATION_HAS_ACCURACY;return 0;
}/* this is the state of our connection to the qemu_gpsd daemon */
typedef struct {int                     init;int                     fd;GpsCallbacks            callbacks;pthread_t               thread;int                     control[2];
} GpsState;static GpsState  _gps_state[1];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;char *ptr;D("Received: '%.*s'", r->pos, r->in);/*********add by jhuang for call back NMEA***************/ /*     if(r->callback.nmea_cb) { r->callback.nmea_cb(r->fix.timestamp,r->in,r->pos); }*//***************************************************/ 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);}}
#endiftok = 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.ptr = tok.p;tok.p += 2;if ( !memcmp(tok.p, "GGA", 3) ) {// GPS fixToken  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 ?int is_beidou = !memcmp(ptr, "BD", 2);#ifdef Ublox_6M   /* do something ? */  {  D("may%s,%d,%s,gsa\n",__FILE__,__LINE__,__FUNCTION__);  Token tok_fixStatus = nmea_tokenizer_get(tzer, 2);  int i;  if (tok_fixStatus.p[0] != '\0' && tok_fixStatus.p[0] != '1') {//等于'1'的话表示定位不可用模式  Token tok_accuracy = nmea_tokenizer_get(tzer, 15);//position dilution of precision dop   nmea_reader_update_accuracy(r, tok_accuracy);  if(!is_beidou)//因为GPGSA在BDGSA前面，所以第一次进来为GPGSA，这时要清零r->sv_status.used_in_fix_mask = 0ul;  D("\n");  for (i = 3; i <= 14; ++i){  Token tok_prn = nmea_tokenizer_get(tzer, i);  int prn = str2int(tok_prn.p, tok_prn.end);  D("gsa,prn=%d,",prn);  if (prn > 0){  r->sv_status.used_in_fix_mask |= (1ul << ( prn-1)); //这里有可能BD和GP的PRN号一样，就覆盖了，暂时不修改了,这里要prn-1,是因为//prn最大值为32，所以要减1，否则左移会溢出啊, 要完善的支持BD和GP，还要在//framework的GpsStatus.java-> setStatus方法中处理可用卫星的问题  r->sv_status_changed = 1;  }  }D("\n");  D("%s: fix mask is %x", __FUNCTION__, r->sv_status.used_in_fix_mask);  //   D(" [log hit][%s:%d] fix.flags=0x%x ", __FUNCTION__, __LINE__, r->fix.flags);    }  D(" [log hit][%s:%d] fix.flags=0x%x ", __FUNCTION__, __LINE__, r->fix.flags);  }
#endif   } //
#ifdef Ublox_6M   else if ( !memcmp(tok.p, "GSV", 3) ) {  int is_beidou = !memcmp(ptr, "BD", 2);D("sclu is_Beidou = %d", is_beidou);D("may%s,%d,%s,gsV\n",__FILE__,__LINE__,__FUNCTION__);  Token tok_noSatellites = nmea_tokenizer_get(tzer, 3);  int noSatellites = str2int(tok_noSatellites.p, tok_noSatellites.end);  D("%d,inview=%d,\n",__LINE__,noSatellites);    if (noSatellites > 0) {  Token tok_noSentences = nmea_tokenizer_get(tzer, 1); // Token tok_sentence     = nmea_tokenizer_get(tzer, 2);  int sentence = str2int(tok_sentence.p, tok_sentence.end);//当前解析的是第几个GSV语句  int totalSentences = str2int(tok_noSentences.p, tok_noSentences.end);//一共有多少个GSV语句  D("%d,gsv_index=%d,gsv_total=%d\n",__LINE__,sentence,totalSentences);    int curr;  int i;  if ((sentence == 1) && !is_beidou) {  D("msg_index=%d\n",sentence);  //  r->sv_status_changed = 0;   r->sv_status.num_svs = 0; //sv_list的下标，只有$GPGSV当前语句序号为1时候才会清零，$BDGSV时候不会，而是继续递增 r->sv_status.ephemeris_mask=0ul;  r->sv_status.almanac_mask=0ul;  }  curr = r->sv_status.num_svs;  i = 0;  if(is_beidou && (sentence == 1)){noSatellites += r->sv_status.num_svs;D("sclu add beidou total num");}while (i < 4 && r->sv_status.num_svs < noSatellites){  Token    tok_prn = nmea_tokenizer_get(tzer, i * 4 + 4);  Token    tok_elevation = nmea_tokenizer_get(tzer, i * 4 + 5);  Token    tok_azimuth = nmea_tokenizer_get(tzer, i * 4 + 6);  Token    tok_snr = nmea_tokenizer_get(tzer, i * 4 + 7);  r->sv_status.sv_list[curr].prn = str2int(tok_prn.p, tok_prn.end);  if(is_beidou){//北斗卫星编号加上偏移量，避免与GPS冲突D("sclu, number = %d", r->sv_status.sv_list[curr].prn);//r->sv_status.sv_list[curr].prn += 100;}r->sv_status.sv_list[curr].elevation = str2float(tok_elevation.p, tok_elevation.end);  r->sv_status.sv_list[curr].azimuth = str2float(tok_azimuth.p, tok_azimuth.end);  r->sv_status.sv_list[curr].snr = str2float(tok_snr.p, tok_snr.end);  r->sv_status.ephemeris_mask|=(1ul << (r->sv_status.sv_list[curr].prn-1));  r->sv_status.almanac_mask|=(1ul << (r->sv_status.sv_list[curr].prn-1));           r->sv_status.num_svs += 1;  D("**********curr=%d\n",curr);  D("%d,prn=%d:snr=%f\n",__LINE__,r->sv_status.sv_list[curr].prn,r->sv_status.sv_list[curr].snr);  curr += 1;  i += 1;  }  if ((sentence == totalSentences) && is_beidou) { // $GPGSV和$BDGSV一起解析完了才可以上报D("msg=%d,msgindex=%d, curr=%d",totalSentences,sentence, curr);
#ifdef Ublox_6M   r->callback.sv_status_cb=_gps_state->callbacks.sv_status_cb;  if (r->sv_status_changed !=0) {  if (r->callback.sv_status_cb) {  #if GPS_DEBUG   D("%d,SV_STATSU,change=%d\n",__LINE__,r->sv_status_changed);  int nums=r->sv_status.num_svs;  D("num_svs=%d,emask=%x,amask=%x,inusemask=%x\n",r->sv_status.num_svs,r->sv_status.ephemeris_mask,r->sv_status.almanac_mask,r->sv_status.used_in_fix_mask);  D("************88\n");        while(nums)  {  nums--;  D("prn=%d:snr=%f\n",r->sv_status.sv_list[nums].prn,r->sv_status.sv_list[nums].snr);  }D("************88\n");
#endif   r->callback.sv_status_cb( &(r->sv_status) );  r->sv_status_changed = 0;  }else {  D("no callback, keeping status data until needed !");  }  }
#endif   }  D("%s: GSV message with total satellites %d", __FUNCTION__, noSatellites);   }           }
#endifelse if ( !memcmp(tok.p, "GLL", 3) ) {  Token tok_fixstaus = nmea_tokenizer_get(tzer,6);  if (tok_fixstaus.p[0] == 'A') {  Token tok_latitude = nmea_tokenizer_get(tzer,1);  Token tok_latitudeHemi = nmea_tokenizer_get(tzer,2);  Token tok_longitude = nmea_tokenizer_get(tzer,3);  Token tok_longitudeHemi = nmea_tokenizer_get(tzer,4);  Token tok_time = nmea_tokenizer_get(tzer,5);  nmea_reader_update_time(r, tok_time);  nmea_reader_update_latlong(r, tok_latitude, tok_latitudeHemi.p[0], tok_longitude, tok_longitudeHemi.p[0]);  }  }  /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 );}*/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 );
#ifdef Ublox_6M   r->callback.location_cb=_gps_state->callbacks.location_cb;  r->callback.nmea_cb=_gps_state->callbacks.nmea_cb;  r->callback.status_cb=_gps_state->callbacks.status_cb;  if (r->callback.status_cb) {  D("report,status,flags=%d\n",r->fix.flags);  r->callback.status_cb( (struct GpsStatus *)&(r->fix.flags) );  }  if (r->callback.location_cb) {  D("location_cb report:r->fix.flags=%d,r->latitude=%f,r->longitude=%f,r->altitude=%f,r->speed=%f,r->bearing=%f,r->accuracy=%f\n",r->fix.flags,r->fix.latitude,r->fix.longitude,r->fix.altitude,r->fix.speed,r->fix.bearing,r->fix.accuracy);  r->callback.location_cb( &r->fix );  r->fix.flags = 0;  }  if (r->callback.nmea_cb) {  D("report,timestamp=%llx,%llu\n",r->fix.timestamp,r->fix.timestamp);  r->callback.nmea_cb( r->fix.timestamp,r->in,r->pos );  }  #else   r->callback=_gps_state.callbacks->location_cb;  //r->callback.nmea_cb=_gps_state->callbacks.nmea_cb;   if (r->callback) {D("if2 (r->callback.location_cb)\n");  r->callback( &r->fix );  r->fix.flags = 0;  }
#endif   }  }  else {tok.p -= 2;D("unknown sentence '%.*s", tok.end-tok.p, tok.p);}if (r->fix.flags != 0) {
#if GPS_DEBUGchar   temp[256];char*  p   = temp;char*  end = p + sizeof(temp);struct tm   utc;p += snprintf( p, end-p, "sending fix" );if (r->fix.flags & GPS_LOCATION_HAS_LAT_LONG) {p += snprintf(p, end-p, " lat=%g lon=%g", r->fix.latitude, r->fix.longitude);}if (r->fix.flags & GPS_LOCATION_HAS_ALTITUDE) {p += snprintf(p, end-p, " altitude=%g", r->fix.altitude);}if (r->fix.flags & GPS_LOCATION_HAS_SPEED) {p += snprintf(p, end-p, " speed=%g", r->fix.speed);}if (r->fix.flags & GPS_LOCATION_HAS_BEARING) {p += snprintf(p, end-p, " bearing=%g", r->fix.bearing);}if (r->fix.flags & GPS_LOCATION_HAS_ACCURACY) {p += snprintf(p,end-p, " accuracy=%g", r->fix.accuracy);}gmtime_r( (time_t*) &r->fix.timestamp, &utc );p += snprintf(p, end-p, " time=%s", asctime( &utc ) );LOGD("%s",temp);
#endif/*    if (r->callback ) {r->callback( &r->fix );r->fix.flags = 0;}*///else {//  D("no callback, keeping data until needed !");// }}
}static void
nmea_reader_addc( NmeaReader*  r, int  c )
{if (r->overflow) {r->overflow = (c != '\n');return;}if (r->pos >= (int) sizeof(r->in)-1 ) {r->overflow = 1;r->pos      = 0;return;}r->in[r->pos] = (char)c;r->pos       += 1;if (c == '\n') {nmea_reader_parse( r );r->pos = 0;}
}/*****************************************************************/
/*****************************************************************/
/*****                                                       *****/
/*****       C O N N E C T I O N   S T A T E                 *****/
/*****                                                       *****/
/*****************************************************************/
/*****************************************************************//* commands sent to the gps thread */
enum {CMD_QUIT  = 0,CMD_START = 1,CMD_STOP  = 2
};static void
gps_state_done( GpsState*  s )
{// tell the thread to quit, and wait for itchar   cmd = CMD_QUIT;void*  dummy;write( s->control[0], &cmd, 1 );pthread_join(s->thread, &dummy);// close the control socket pairclose( s->control[0] ); s->control[0] = -1;close( s->control[1] ); s->control[1] = -1;// close connection to the QEMU GPS daemonclose( s->fd ); s->fd = -1;s->init = 0;
}static void
gps_state_start( GpsState*  s )
{char  cmd = CMD_START;int   ret;do { ret=write( s->control[0], &cmd, 1 ); }while (ret < 0 && errno == EINTR);if (ret != 1)D("%s: could not send CMD_START command: ret=%d: %s",__FUNCTION__, ret, strerror(errno));
}static void
gps_state_stop( GpsState*  s )
{char  cmd = CMD_STOP;int   ret;do { ret=write( s->control[0], &cmd, 1 ); }while (ret < 0 && errno == EINTR);if (ret != 1)D("%s: could not send CMD_STOP command: ret=%d: %s",__FUNCTION__, ret, strerror(errno));
}static int
epoll_register( int  epoll_fd, int  fd )
{struct epoll_event  ev;int                 ret, flags;/* important: make the fd non-blocking */flags = fcntl(fd, F_GETFL);fcntl(fd, F_SETFL, flags | O_NONBLOCK);ev.events  = EPOLLIN;ev.data.fd = fd;do {ret = epoll_ctl( epoll_fd, EPOLL_CTL_ADD, fd, &ev );} while (ret < 0 && errno == EINTR);return ret;
}static int
epoll_deregister( int  epoll_fd, int  fd )
{int  ret;do {ret = epoll_ctl( epoll_fd, EPOLL_CTL_DEL, fd, NULL );} while (ret < 0 && errno == EINTR);return ret;
}/* this is the main thread, it waits for commands from gps_state_start/stop and,* when started, messages from the QEMU GPS daemon. these are simple NMEA sentences* that must be parsed to be converted into GPS fixes sent to the framework*/static void
gps_state_thread( void*  arg )
{GpsState*   state = (GpsState*) arg;NmeaReader  reader[1];int         epoll_fd   = epoll_create(2);int         started    = 0;int         gps_fd     = state->fd;int         control_fd = state->control[1];nmea_reader_init( reader );// register control file descriptors for pollingepoll_register( epoll_fd, control_fd );epoll_register( epoll_fd, gps_fd );D("gps thread running");// now loopfor (;;) {struct epoll_event   events[2];int                  ne, nevents;nevents = epoll_wait( epoll_fd, events, 2, -1 );if (nevents < 0) {if (errno != EINTR)LOGE("epoll_wait() unexpected error: %s", strerror(errno));continue;}D("gps thread received %d events", nevents);for (ne = 0; ne < nevents; ne++) {if ((events[ne].events & (EPOLLERR|EPOLLHUP)) != 0) {LOGE("EPOLLERR or EPOLLHUP after epoll_wait() !?");goto Exit;}if ((events[ne].events & EPOLLIN) != 0) {int  fd = events[ne].data.fd;if (fd == control_fd){char  cmd = 255;int   ret;D("gps control fd event");do {ret = read( fd, &cmd, 1 );} while (ret < 0 && errno == EINTR);if (cmd == CMD_QUIT) {D("gps thread quitting on demand");goto Exit;}else if (cmd == CMD_START) {if (!started) {D("gps thread starting  location_cb=%p", state->callbacks.location_cb);started = 1;//******************************************************************g_status.status=GPS_STATUS_SESSION_BEGIN;//??ʼ????state->callbacks.status_cb(&g_status); //******************************************************************    nmea_reader_set_callback( reader, state->callbacks.location_cb );LOGE("%d",gps_fd);}}else if (cmd == CMD_STOP) {if (started) {D("gps thread stopping");started = 0;//********************************************************************g_status.status=GPS_STATUS_SESSION_END; //ֹͣstate->callbacks.status_cb(&g_status); //********************************************************************nmea_reader_set_callback( reader, NULL );}}}else if (fd == gps_fd){char  buff[32];D("gps fd event");for (;;) {int  nn, ret;ret = read( fd, buff, sizeof(buff) );if (ret < 0) {if (errno == EINTR)continue;if (errno != EWOULDBLOCK)LOGE("error while reading from gps daemon socket: %s:", strerror(errno));break;}D("received %d bytes: %.*s", ret, ret, buff);for (nn = 0; nn < ret; nn++)nmea_reader_addc( reader, buff[nn] );}D("gps fd event end");}else{LOGE("epoll_wait() returned unkown fd %d ?", fd);}}}}
Exit:return ;
}static void
gps_state_init( GpsState*  state )
{state->init       = 1;state->control[0] = -1;state->control[1] = -1;state->fd         = -1;int ret = -1;struct termios gps_termios;//*****************************************************************************state->fd= open("/dev/ttyS3",O_RDWR|O_NOCTTY|O_NDELAY);//?????õ???UART1if( state->fd < 0){LOGE("open port /dev/ttyS3 ERROR..state->fd=%s\n",strerror(state->fd)); exit(0);}elseLOGE("open port:/dev/ttyS3 succceed..state->fd=%d\n",state->fd);if(fcntl( state->fd,F_SETFL,0)<0)LOGE("fcntl F_SETFL\n");{LOGI(">>>> Port setup..\n");int err;tcflush(state->fd, TCIOFLUSH);if ((err = tcgetattr(state->fd,&gps_termios)) != 0){LOGI("tcgetattr(%d) = %d,errno %d\r\n",state->fd,err,errno);close(state->fd);}gps_termios.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IXON);gps_termios.c_oflag &= ~OPOST;gps_termios.c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);gps_termios.c_cflag &= ~(CSIZE|PARENB);gps_termios.c_cflag |= CS8;gps_termios.c_cflag &= ~CRTSCTS;//no flow controltcsetattr(state->fd, TCSANOW, &gps_termios);tcflush(state->fd, TCIOFLUSH);tcsetattr(state->fd, TCSANOW, &gps_termios);tcflush(state->fd, TCIOFLUSH);tcflush(state->fd, TCIOFLUSH);if (cfsetispeed(&gps_termios,B115200)){LOGE("cfsetispeed.. errno..\r\n");close(state->fd);//return(-1);}// Set the output baud rates in the termios.if (cfsetospeed(&gps_termios,B115200)){LOGE("cfsetispeed.. errno..\r\n");close(state->fd);//return(-1);}tcsetattr(state->fd,TCSANOW,&gps_termios);LOGE("Port setup finished..\n");}if (state->fd < 0) {LOGD("no gps emulation detected");return;}//**********************************************************************if ( socketpair( AF_LOCAL, SOCK_STREAM, 0, state->control ) < 0 ) {LOGE("could not create thread control socket pair: %s", strerror(errno));goto Fail;}/* if ( pthread_create( &state->thread, NULL, gps_state_thread, state ) != 0 ) {LOGE("could not create gps thread: %s", strerror(errno));goto Fail;}*///***********************************************************************LOGE("gps state initialized before");state->thread=state->callbacks.create_thread_cb("gps_state_thread",gps_state_thread,state);//**************************************************************************//    D("gps state initialized");LOGE("gps state initialized");return;Fail:gps_state_done( state );
}/*****************************************************************/
/*****************************************************************/
/*****                                                       *****/
/*****       I N T E R F A C E                               *****/
/*****                                                       *****/
/*****************************************************************/
/*****************************************************************/static int
qemu_gps_init(GpsCallbacks* callbacks)
{system("echo 1 > /sys/devices/platform/gps_power/bcm_gps_power_state");GpsState*  s = _gps_state;D("%s", __FUNCTION__);/**************************************************/s->callbacks = *callbacks; //ע???ص?????,JNI????\C0\B4?Ļص?????g_status.status=GPS_STATUS_ENGINE_ON;//????״̬ ͨ?絫??û??ʼ????s->callbacks.status_cb(&g_status);/******************************************************/if (!s->init)gps_state_init(s);if (s->fd < 0)return -1;// s->callbacks = *callbacks;return 0;
}static void
qemu_gps_cleanup(void)
{GpsState*  s = _gps_state;D("%s", __FUNCTION__);if (s->init)gps_state_done(s);system("echo 0 > /sys/devices/platform/gps_power/bcm_gps_power_state");
}static int
qemu_gps_start()
{GpsState*  s = _gps_state;D("%s", __FUNCTION__);if (!s->init) {D("%s: called with uninitialized state !!", __FUNCTION__);return -1;}gps_state_start(s);return 0;
}static int
qemu_gps_stop()
{GpsState*  s = _gps_state;D("%s", __FUNCTION__);if (!s->init) {D("%s: called with uninitialized state !!", __FUNCTION__);return -1;}D("%s: called", __FUNCTION__);gps_state_stop(s);return 0;
}static int
qemu_gps_inject_time(GpsUtcTime time, int64_t timeReference, int uncertainty)
{return 0;
}static int
qemu_gps_inject_location(double latitude, double longitude, float accuracy)
{return 0;
}static void
qemu_gps_delete_aiding_data(GpsAidingData flags)
{
}static int qemu_gps_set_position_mode(GpsPositionMode mode, GpsPositionRecurrence recurrence,uint32_t min_interval, uint32_t preferred_accuracy, uint32_t preferred_time)//(GpsPositionMode mode, int fix_frequency)
{// FIXME - support fix_frequencyreturn 0;
}static const void*
qemu_gps_get_extension(const char* name)
{// no extensions supportedreturn NULL;
}static const GpsInterface  qemuGpsInterface = {sizeof(GpsInterface),qemu_gps_init,qemu_gps_start,qemu_gps_stop,qemu_gps_cleanup,qemu_gps_inject_time,qemu_gps_inject_location,qemu_gps_delete_aiding_data,qemu_gps_set_position_mode,qemu_gps_get_extension,
};const GpsInterface* gps__get_gps_interface(struct gps_device_t* dev)
{return &qemuGpsInterface;
}static int open_gps(const struct hw_module_t* module, char const* name,struct hw_device_t** device)
{struct gps_device_t *dev = malloc(sizeof(struct gps_device_t));memset(dev, 0, sizeof(*dev));dev->common.tag = HARDWARE_DEVICE_TAG;dev->common.version = 0;dev->common.module = (struct hw_module_t*)module;//    dev->common.close = (int (*)(struct hw_device_t*))close_lights;dev->get_gps_interface = gps__get_gps_interface;*device = (struct hw_device_t*)dev;return 0;
}static struct hw_module_methods_t gps_module_methods = {.open = open_gps
};const struct hw_module_t HAL_MODULE_INFO_SYM = {.tag = HARDWARE_MODULE_TAG,.version_major = 1,.version_minor = 0,.id = GPS_HARDWARE_MODULE_ID,.name = "Goldfish GPS Module",.author = "The Android Open Source Project",.methods = &gps_module_methods,
};

下面简单分析GPS源代码的上报过程，流程图如下所示：

应用：

    lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);lm.addGpsStatusListener(statuslistener);
private GpsStatus.Listener statuslistener = new GpsStatus.Listener(){//实现public interface Listener 接口public void onGpsStatusChanged(int event){}
};

调用LocationManager.java：

    1331             GpsStatusListenerTransport transport = new GpsStatusListenerTransport(listener);1332             result = mService.addGpsStatusListener(transport);1333             if (result) {1334                 mGpsStatusListeners.put(listener, transport);1335             }

1331行：

    1228         GpsStatusListenerTransport(GpsStatus.Listener listener) {                                                 1229             mListener = listener;1230             mNmeaListener = null;1231         }

GpsStatusListenerTransport类提供了几个方法如onGpsStarted，onGpsStopped，onFirstFix，onSvStatusChanged，onNmeaReceived等，而在这些方法中，会调用
mGpsHandler.sendMessage(msg)，将消息发送给mListener，这样前面应用中实现的接口onGpsStatusChanged就会接收到消息了；
现在回到谁会调用这些方法来发送消息的问题上？当然是LocationManagerService.java，所以要将GpsStatusListenerTransport注册到服务中，这是在1332行中实现的，所以看
LocationManagerService.java的addGpsStatusListener方法：

    1303         try {1304             mGpsStatusProvider.addGpsStatusListener(listener);1305         } catch (RemoteException e) {1306             Slog.e(TAG, "mGpsStatusProvider.addGpsStatusListener failed", e);1307             return false;1308         }

mGpsStatusProvider是什么？
mGpsStatusProvider = gpsProvider.getGpsStatusProvider();
gpsProvider又是什么?
GpsLocationProvider gpsProvider = new GpsLocationProvider(mContext, this);
看来要进入GpsLocationProvider类了，这个类是和GPS的JNI层打交道的地方，看他的getGpsStatusProvider方法：

     343     public IGpsStatusProvider getGpsStatusProvider() {344         return mGpsStatusProvider;                                                                                 345     }

mGpsStatusProvider是：

     296     private final IGpsStatusProvider mGpsStatusProvider = new IGpsStatusProvider.Stub() {297         public void addGpsStatusListener(IGpsStatusListener listener) throws RemoteException {298             if (listener == null) {299                 throw new NullPointerException("listener is null in addGpsStatusListener");300             }301 302             synchronized(mListeners) {303                 IBinder binder = listener.asBinder();304                 int size = mListeners.size();305                 for (int i = 0; i < size; i++) {306                     Listener test = mListeners.get(i);307                     if (binder.equals(test.mListener.asBinder())) {308                         // listener already added309                         return;310                     }311                 }312 313                 Listener l = new Listener(listener);314                 binder.linkToDeath(l, 0);315                 mListeners.add(l);316             }317         }

看来是实现了IGpsStatusProvider接口的一个服务类啊，所以1304行就是调用这里297行的addGpsStatusListener方法把客户端LocationManager中的listener添加到这里来啊。
307行先判断listener是否已经添加，接着313行，new Listener，315行的mListeners是ArrayList类型，就是把313创建的Listener加到动态数组中。
想想看，在GpsStatusProvider类中肯顶在某个地方会遍历mListeners中的成员，以便回调里面的方法，将数据发送出去；也就是说存在某个机制，已经运行起来了？这是什么机制？
其实没有什么机制，只不过GpsStatusProvider类实现了reportStatus和reportSvStatus方法，这些方法会提供给JNI层，也就是JNI主动调用java层的方法？那什么时候调用呢，进入
JNI层看看就知道了：
method_reportSvStatus = env->GetMethodID(clazz, "reportSvStatus", "()V");//看名字就知道是对应java的reportSvStatus方法了

     90 static void sv_status_callback(GpsSvStatus* sv_status)91 {92     JNIEnv* env = AndroidRuntime::getJNIEnv();93     memcpy(&sGpsSvStatus, sv_status, sizeof(sGpsSvStatus));94     env->CallVoidMethod(mCallbacksObj, method_reportSvStatus);//这里CallVoidMethod就是调用method_reportSvStatus方法，即java层的reportSvStatus95     checkAndClearExceptionFromCallback(env, __FUNCTION__);96 }

sv_status_callback则在函数指针数组中被赋值：

    139 GpsCallbacks sGpsCallbacks = {140     sizeof(GpsCallbacks),141     location_callback,142     status_callback,143     sv_status_callback,                                                                                            144     nmea_callback,145     set_capabilities_callback,146     acquire_wakelock_callback,147     release_wakelock_callback,148     create_thread_callback,149     request_utc_time_callback,150 };

GpsCallbacks类在libhardware/include/hardware/gps.h定义：

    368 typedef struct {369     /** set to sizeof(GpsCallbacks) */                                                                                      370     size_t      size;371     gps_location_callback location_cb;372     gps_status_callback status_cb;373     gps_sv_status_callback sv_status_cb;374     gps_nmea_callback nmea_cb;375     gps_set_capabilities set_capabilities_cb;376     gps_acquire_wakelock acquire_wakelock_cb;377     gps_release_wakelock release_wakelock_cb;378     gps_create_thread create_thread_cb;379     gps_request_utc_time request_utc_time_cb;380 } GpsCallbacks;

这里是HAL层主动调用JNI层的方法，看看是怎么回事，在JNI的android_location_GpsLocationProvider_is_supported中：
   if (!sGpsInterface || sGpsInterface->init(&sGpsCallbacks) != 0)
就是这一句，把sGpsCallbacks的地址传递了给HAL层，这里的sGpsInterface当然是在经过
   hw_get_module(GPS_HARDWARE_MODULE_ID, (hw_module_t const**)&module);
   module->methods->open(module, GPS_HARDWARE_MODULE_ID, &device);
   sGpsInterface = gps_device->get_gps_interface(gps_device);
之后得到的。
所以进入HAL层看看吧：

    1300 static const GpsInterface  qemuGpsInterface = {1301     sizeof(GpsInterface),1302     qemu_gps_init,1303     qemu_gps_start,1304     qemu_gps_stop,1305     qemu_gps_cleanup,1306     qemu_gps_inject_time,1307     qemu_gps_inject_location,1308     qemu_gps_delete_aiding_data,1309     qemu_gps_set_position_mode,1310     qemu_gps_get_extension,1311 };1312 1313 const GpsInterface* gps__get_gps_interface(struct gps_device_t* dev)1314 {1315     return &qemuGpsInterface;//返回给JNI层的地址1316 }

GpsInterface类的定义：

    384 typedef struct {386     size_t          size;391     int   (*init)( GpsCallbacks* callbacks );394     int   (*start)( void );397     int   (*stop)( void );400     void  (*cleanup)( void );403     int   (*inject_time)(GpsUtcTime time, int64_t timeReference,404                          int uncertainty);411     int  (*inject_location)(double latitude, double longitude, float accuracy);418     void  (*delete_aiding_data)(GpsAidingData flags);425     int   (*set_position_mode)(GpsPositionMode mode, GpsPositionRecurrence recurrence,426             uint32_t min_interval, uint32_t preferred_accuracy, uint32_t preferred_time);429     const void* (*get_extension)(const char* name);430 } GpsInterface;

看到了没，看来不用多说，JNI调用了qemu_gps_init方法：

    1198 qemu_gps_init(GpsCallbacks* callbacks)                                                                                   1199 {1201     GpsState*  s = _gps_state;1206     s->callbacks = *callbacks;1208     g_status.status=GPS_STATUS_ENGINE_ON;1210     s->callbacks.status_cb(&g_status);1214     if (!s->init)1215         gps_state_init(s);1217     if (s->fd < 0)1218         return -1;1222     return 0;1223 }

这样1206行就得到了JNI层的sv_status_callback结构体地址，然后就可以调用它了，什么时候调用啊？在线程中检测到串口有GPS数据上报了就会调用，在线程中解析GPS的GSV数据
后会调用r->callback.sv_status_cb( &(r->sv_status) )：

     90 static void sv_status_callback(GpsSvStatus* sv_status)91 {92     JNIEnv* env = AndroidRuntime::getJNIEnv();93     memcpy(&sGpsSvStatus, sv_status, sizeof(sGpsSvStatus));                                                                              94     env->CallVoidMethod(mCallbacksObj, method_reportSvStatus);95     checkAndClearExceptionFromCallback(env, __FUNCTION__);96 }

93行把数据保存到JNI层，94行调用JAVA层的reportSvStatus方法：

    1209     private void reportSvStatus() {1210 1211         int svCount = native_read_sv_status(mSvs, mSnrs, mSvElevations, mSvAzimuths, mSvMasks);1212 1213         synchronized(mListeners) {1214             int size = mListeners.size();1215             for (int i = 0; i < size; i++) {1216                 Listener listener = mListeners.get(i);1217                 try {1218                     listener.mListener.onSvStatusChanged(svCount, mSvs, mSnrs,1219                             mSvElevations, mSvAzimuths, mSvMasks[EPHEMERIS_MASK],                          1220                             mSvMasks[ALMANAC_MASK], mSvMasks[USED_FOR_FIX_MASK]);1221                 } catch (RemoteException e) {1222                     Log.w(TAG, "RemoteException in reportSvInfo");1223                     mListeners.remove(listener);1224                     // adjust for size of list changing1225                     size--;1226                 }1227             }1228         }

1211行它又调用JNI的native_read_sv_status，它不做别的事情，就是读取前面保存在HAL层的数据，因为前面HAL层只是把数据拷贝到JNI层的变量中：

    346 static jint android_location_GpsLocationProvider_read_sv_status(JNIEnv* env, jobject obj,347         jintArray prnArray, jfloatArray snrArray, jfloatArray elevArray, jfloatArray azumArray,348         jintArray maskArray)349 {350     // this should only be called from within a call to reportSvStatus351 352     jint* prns = env->GetIntArrayElements(prnArray, 0);353     jfloat* snrs = env->GetFloatArrayElements(snrArray, 0);354     jfloat* elev = env->GetFloatArrayElements(elevArray, 0);355     jfloat* azim = env->GetFloatArrayElements(azumArray, 0);356     jint* mask = env->GetIntArrayElements(maskArray, 0);357 358     int num_svs = sGpsSvStatus.num_svs;359     for (int i = 0; i < num_svs; i++) {360         prns[i] = sGpsSvStatus.sv_list[i].prn;361         snrs[i] = sGpsSvStatus.sv_list[i].snr;362         elev[i] = sGpsSvStatus.sv_list[i].elevation;363         azim[i] = sGpsSvStatus.sv_list[i].azimuth;364     }365     mask[0] = sGpsSvStatus.ephemeris_mask;366     mask[1] = sGpsSvStatus.almanac_mask;367     mask[2] = sGpsSvStatus.used_in_fix_mask;                                                                          368 369     env->ReleaseIntArrayElements(prnArray, prns, 0);370     env->ReleaseFloatArrayElements(snrArray, snrs, 0);371     env->ReleaseFloatArrayElements(elevArray, elev, 0);372     env->ReleaseFloatArrayElements(azumArray, azim, 0);373     env->ReleaseIntArrayElements(maskArray, mask, 0);374     return num_svs;375 }

最终我们的应用也就在onGpsStatusChanged方法中得到了要处理的数据啦

2013.08.22续：

由于要做一个测试软件来测试GPS性能，但是多加了一个北斗的数据，android标准只支持1～32号星，大于32将无法校验该卫星是否用来定位。所以只能增加一个int型来保存北斗的校验值，具体修改的地方如下：

1. hardware/libhardware中：

diff --git a/include/hardware/gps.h b/include/hardware/gps.h
index 69bfd50..895ee4f 100755
--- a/include/hardware/gps.h
+++ b/include/hardware/gps.h
@@ -298,6 +298,11 @@ typedef struct {* were used for computing the most recent position fix.*/uint32_t    used_in_fix_mask;
+
+    /*
+       add for beidou gps
+    */
+    uint32_t    bd_used_in_fix_mask;} GpsSvStatus;

2.beidou_gps.c中：

diff --git a/hardware/libhardware/gps/beidou_gps.c b/hardware/libhardware/gps/beidou_gps.c
index 131a16e..d6001f9 100644
--- a/hardware/libhardware/gps/beidou_gps.c
+++ b/hardware/libhardware/gps/beidou_gps.c
-                if(!is_beidou)
+                if(!is_beidou){r->sv_status.used_in_fix_mask = 0ul;
+                    r->sv_status.bd_used_in_fix_mask = 0ul;
+                }D("\n");  for (i = 3; i <= 14; ++i){  @@ -571,9 +573,13 @@ nmea_reader_parse( NmeaReader*  r )int prn = str2int(tok_prn.p, tok_prn.end);  D("gsa,prn=%d,",prn);  if (prn > 0){
-                        r->sv_status.used_in_fix_mask |= (1ul << ( prn-1));
-                        r->sv_status_changed = 1;
+                        if(is_beidou){
+                            D("sclu %d, prn=%d", __LINE__, prn);
+                            r->sv_status.bd_used_in_fix_mask |= (1ul << ( prn-1));
+                        }else
+                            r->sv_status.used_in_fix_mask |= (1ul << ( prn-1));  +                        r->sv_status_changed = 1;  }

3.frameworks/base中:

diff --git a/location/java/android/location/GpsStatus.java b/location/java/android/location/GpsStatus.java
index 4af55a6..73e3bcc 100644
--- a/location/java/android/location/GpsStatus.java
+++ b/location/java/android/location/GpsStatus.java
@@ -18,6 +18,7 @@ package android.location;import java.util.Iterator;import java.util.NoSuchElementException;
+import android.util.Log;/**
@@ -140,26 +141,35 @@ public final class GpsStatus {*/synchronized void setStatus(int svCount, int[] prns, float[] snrs,float[] elevations, float[] azimuths, int ephemerisMask,
-            int almanacMask, int usedInFixMask) {
+            int almanacMask, int usedInFixMask, int bdusedInFixMask) {int i;for (i = 0; i < mSatellites.length; i++) {mSatellites[i].mValid = false;}
-
+       Log.e("sclu", "ephemeris = " + Integer.toBinaryString(ephemerisMask) + ", almanac = " + Integer.toBinaryString(almanacMask) + ", usedinfix = " + Integefor (i = 0; i < svCount; i++) {
+    int prn = prns[i] - 1;
-            int prnShift = (1 << prn);
+            int prnShift;
+            if(prns[i] <= 32)
+                prnShift = (1 << (prn));
+            else
+                prnShift = (1 << (prn - 100));if (prn >= 0 && prn < mSatellites.length) {GpsSatellite satellite = mSatellites[prn];
-
+                Log.e("sclu", "prns[" + i + "] = " + prns[i]); satellite.mValid = true;satellite.mSnr = snrs[i];satellite.mElevation = elevations[i];satellite.mAzimuth = azimuths[i];satellite.mHasEphemeris = ((ephemerisMask & prnShift) != 0);satellite.mHasAlmanac = ((almanacMask & prnShift) != 0);
-                satellite.mUsedInFix = ((usedInFixMask & prnShift) != 0);
+                if(prns[i] <= 32){
+                    satellite.mUsedInFix = ((usedInFixMask & prnShift) != 0);
+                }else{
+                    satellite.mUsedInFix = ((bdusedInFixMask & prnShift) != 0);
+                }}}}
diff --git a/location/java/android/location/IGpsStatusListener.aidl b/location/java/android/location/IGpsStatusListener.aidl
index 62b1c6b..6a6bac9 100644
--- a/location/java/android/location/IGpsStatusListener.aidl
+++ b/location/java/android/location/IGpsStatusListener.aidl
@@ -28,6 +28,6 @@ oneway interface IGpsStatusListenervoid onFirstFix(int ttff);void onSvStatusChanged(int svCount, in int[] prns, in float[] snrs, in float[] elevations, in float[] azimuths,
-            int ephemerisMask, int almanacMask, int usedInFixMask);
+            int ephemerisMask, int almanacMask, int usedInFixMask, int bdusedInFixMask);void onNmeaReceived(long timestamp, String nmea);}
diff --git a/location/java/android/location/LocationManager.java b/location/java/android/location/LocationManager.java
index 91d8bc1..5c1cfa9 100644
--- a/location/java/android/location/LocationManager.java
+++ b/location/java/android/location/LocationManager.java
@@ -1263,10 +1263,10 @@ public class LocationManager {public void onSvStatusChanged(int svCount, int[] prns, float[] snrs,float[] elevations, float[] azimuths, int ephemerisMask,
-                int almanacMask, int usedInFixMask) {
+                int almanacMask, int usedInFixMask, int bdusedInFixMask) {if (mListener != null) {mGpsStatus.setStatus(svCount, prns, snrs, elevations, azimuths,
-                        ephemerisMask, almanacMask, usedInFixMask);
+                        ephemerisMask, almanacMask, usedInFixMask, bdusedInFixMask);Message msg = Message.obtain();msg.what = GpsStatus.GPS_EVENT_SATELLITE_STATUS;
diff --git a/services/java/com/android/server/location/GpsLocationProvider.java b/services/java/com/android/server/location/GpsLocationProvider.java
index bad57d5..82159a1 100755
--- a/services/java/com/android/server/location/GpsLocationProvider.java
+++ b/services/java/com/android/server/location/GpsLocationProvider.java
@@ -1217,7 +1217,7 @@ public class GpsLocationProvider implements LocationProviderInterface {try {listener.mListener.onSvStatusChanged(svCount, mSvs, mSnrs, mSvElevations, mSvAzimuths, mSvMasks[EPHEMERIS_MASK],
-                            mSvMasks[ALMANAC_MASK], mSvMasks[USED_FOR_FIX_MASK]);
+                            mSvMasks[ALMANAC_MASK], mSvMasks[USED_FOR_FIX_MASK], mSvMasks[BD_USED_FOR_FIX_MASK]); } catch (RemoteException e) {Log.w(TAG, "RemoteException in reportSvInfo");mListeners.remove(listener);
@@ -1649,13 +1649,15 @@ public class GpsLocationProvider implements LocationProviderInterface {private static final int EPHEMERIS_MASK = 0;private static final int ALMANAC_MASK = 1;private static final int USED_FOR_FIX_MASK = 2;
+    //add for beidou gps
+    private static final int BD_USED_FOR_FIX_MASK = 3;// preallocated arrays, to avoid memory allocation in reportStatus()private int mSvs[] = new int[MAX_SVS];private float mSnrs[] = new float[MAX_SVS];private float mSvElevations[] = new float[MAX_SVS];private float mSvAzimuths[] = new float[MAX_SVS];
-    private int mSvMasks[] = new int[3];
+    private int mSvMasks[] = new int[4];private int mSvCount;// preallocated to avoid memory allocation in reportNmea()private byte[] mNmeaBuffer = new byte[120];
diff --git a/services/jni/com_android_server_location_GpsLocationProvider.cpp b/services/jni/com_android_server_location_GpsLocationProvider.cpp
index c823da5..88abf23 100755
--- a/services/jni/com_android_server_location_GpsLocationProvider.cpp
+++ b/services/jni/com_android_server_location_GpsLocationProvider.cpp
@@ -361,6 +361,7 @@ static jint android_location_GpsLocationProvider_read_sv_status(JNIEnv* env, jobmask[0] = sGpsSvStatus.ephemeris_mask;mask[1] = sGpsSvStatus.almanac_mask;mask[2] = sGpsSvStatus.used_in_fix_mask;
+    mask[3] = sGpsSvStatus.bd_used_in_fix_mask;env->ReleaseIntArrayElements(prnArray, prns, 0);env->ReleaseFloatArrayElements(snrArray, snrs, 0);

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