Simple analysis of Android Qemu GPS module

Android GPS module is gps.default.so in the system/lib/hw/directory, general GPS-enabled mobile phones should implement this module and real GPS hardware interaction

the GPS in QEMU is to construct a gps.default.so, but this so does not deal with real hardware, just an analog interface, its code in in Sdk/emulator/gps/gps_qemu.c

The Qemu container implements a GPS device externally, but this device and Android interaction can only be piped, so Gps_qemu.c's function is to work with the pipeline and provide the Android required GPS functions, as follows:

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,};

QEMU external GPS sends data to the GPS module via the Qemu_channel_name pipeline, format NMEA, so the GPS module has several functions responsible for the parse of these data

The GPS module has a requirement that it must use its callback to create the thread (Gps_state_thread), while the position information callback is only approached (Gps_state_thread) on this line, because the framework Need a VM visible Java thread, Gps_state_thread will be attach to the VM, never callback Java layer function

"Gps_state_thread", Gps_state_thread, state);

So when Qemu_channel_nameGps_state_thread sent to Android framework

Gps.default.so call Epoll function to listen to the file FD, the implementation of the location information in the Gps_state_thread returned

Simple analysis of Android Qemu GPS module