我是从Android的GPS模拟器代码中看到的,觉得很有意思,就记录下来了
首先是结构体的定义:
[cpp]
/* 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 ;
} GpsState;
/* 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 ;
} GpsState;
然后声明结构体指针变量
static GpsState _gps_state ;
正常使用:
[cpp]
static int
qemu_gps_init(GpsCallbacks* callbacks)
{
GpsState* s = _gps_state;
if (!s->init)
gps_state_init(s, callbacks);
if (s->fd < 0)
return -1;
return 0;
}
static int
qemu_gps_init(GpsCallbacks* callbacks)
{
GpsState* s = _gps_state;
if (!s->init)
gps_state_init(s, callbacks);
if (s->fd < 0)
return -1;
return 0;
}