void update()
{
//Calculate time step
float timeStep = stepTimer.getTicks()/1000.f;
//pseudo:
//update any world stuff (background objects, etc)
//NPC AI
//for each npc
//npc.strategize
//for each object in the world
//object.framenumber++
//object.move (x += xv, y += yv)
//handle collisions
//Move for time step
stepTimer.start();
//Calculate FPS
timeText.str("");
SDL_AtomicLock( &gDataLock );
timeText << "FPS: " << framesThisSecond;
SDL_AtomicUnlock( &gDataLock );
if(!gFPSTextTexture.loadFromRenderedText(timeText.str().c_str(), fpsColor))
{
printf("Unable to render FPS texture.\n");
}
}
int fpsworker( void* data )
{
//Work continuously
SDL_AtomicLock( &gDataLock );
bool fpsquit = quit;
SDL_AtomicUnlock( &gDataLock );
while(!fpsquit)
{
SDL_AtomicLock( &gDataLock );
framesThisSecond = countedFrames;
countedFrames = 0;
SDL_AtomicUnlock( &gDataLock );
//Wait one second
SDL_Delay(1000);
}
return 0;
}
/* Routine to get the thread-specific error variable */
SDL_error *
SDL_GetErrBuf(void)
{
static SDL_SpinLock tls_lock;
static SDL_bool tls_being_created;
static SDL_TLSID tls_errbuf;
static SDL_error SDL_global_errbuf;
const SDL_error *ALLOCATION_IN_PROGRESS = (SDL_error *)-1;
SDL_error *errbuf;
/* tls_being_created is there simply to prevent recursion if SDL_TLSCreate() fails.
It also means it's possible for another thread to also use SDL_global_errbuf,
but that's very unlikely and hopefully won't cause issues.
*/
if (!tls_errbuf && !tls_being_created) {
SDL_AtomicLock(&tls_lock);
if (!tls_errbuf) {
SDL_TLSID slot;
tls_being_created = SDL_TRUE;
slot = SDL_TLSCreate();
tls_being_created = SDL_FALSE;
SDL_MemoryBarrierRelease();
tls_errbuf = slot;
}
SDL_AtomicUnlock(&tls_lock);
}
if (!tls_errbuf) {
return &SDL_global_errbuf;
}
SDL_MemoryBarrierAcquire();
errbuf = (SDL_error *)SDL_TLSGet(tls_errbuf);
if (errbuf == ALLOCATION_IN_PROGRESS) {
return &SDL_global_errbuf;
}
if (!errbuf) {
/* Mark that we're in the middle of allocating our buffer */
SDL_TLSSet(tls_errbuf, ALLOCATION_IN_PROGRESS, NULL);
errbuf = (SDL_error *)SDL_malloc(sizeof(*errbuf));
if (!errbuf) {
SDL_TLSSet(tls_errbuf, NULL, NULL);
return &SDL_global_errbuf;
}
SDL_zerop(errbuf);
SDL_TLSSet(tls_errbuf, errbuf, SDL_free);
}
return errbuf;
}
static SDL_bool DequeueEvent_LockFree(SDL_EventQueue *queue, SDL_Event *event)
{
SDL_EventQueueEntry *entry;
unsigned queue_pos;
unsigned entry_seq;
int delta;
SDL_bool status;
#ifdef TEST_SPINLOCK_FIFO
/* This is a gate so an external thread can lock the queue */
SDL_AtomicLock(&queue->lock);
SDL_assert(SDL_AtomicGet(&queue->watcher) == 0);
SDL_AtomicIncRef(&queue->rwcount);
SDL_AtomicUnlock(&queue->lock);
#endif
queue_pos = (unsigned)SDL_AtomicGet(&queue->dequeue_pos);
for ( ; ; ) {
entry = &queue->entries[queue_pos & WRAP_MASK];
entry_seq = (unsigned)SDL_AtomicGet(&entry->sequence);
delta = (int)(entry_seq - (queue_pos + 1));
if (delta == 0) {
/* The entry and the queue position match, try to increment the queue position */
if (SDL_AtomicCAS(&queue->dequeue_pos, (int)queue_pos, (int)(queue_pos+1))) {
/* We own the object, fill it! */
*event = entry->event;
SDL_AtomicSet(&entry->sequence, (int)(queue_pos+MAX_ENTRIES));
status = SDL_TRUE;
break;
}
} else if (delta < 0) {
/* We ran into an old queue entry, which means we've hit empty */
status = SDL_FALSE;
break;
} else {
/* We ran into a new queue entry, get the new queue position */
queue_pos = (unsigned)SDL_AtomicGet(&queue->dequeue_pos);
}
}
#ifdef TEST_SPINLOCK_FIFO
SDL_AtomicDecRef(&queue->rwcount);
#endif
return status;
}
void processInput(SDL_Event e)
{
while(SDL_PollEvent(&e) != 0)
{
if(e.type == SDL_QUIT)
{
SDL_AtomicLock( &gDataLock );
quit = true;
SDL_AtomicUnlock( &gDataLock );
}
}
const Uint8* currentKeyStates = SDL_GetKeyboardState(NULL);
if(currentKeyStates[SDL_SCANCODE_UP])
{
//do something
}
}
/* This thread periodically locks the queue for no particular reason */
static int FIFO_Watcher(void* _data)
{
SDL_EventQueue *queue = (SDL_EventQueue *)_data;
while (queue->active) {
SDL_AtomicLock(&queue->lock);
SDL_AtomicIncRef(&queue->watcher);
while (SDL_AtomicGet(&queue->rwcount) > 0) {
SDL_Delay(0);
}
/* Do queue manipulation here... */
SDL_AtomicDecRef(&queue->watcher);
SDL_AtomicUnlock(&queue->lock);
/* Wait a bit... */
SDL_Delay(1);
}
return 0;
}
static
void RunBasicTest()
{
int value;
SDL_SpinLock lock = 0;
SDL_atomic_t v;
SDL_bool tfret = SDL_FALSE;
printf("\nspin lock---------------------------------------\n\n");
SDL_AtomicLock(&lock);
printf("AtomicLock lock=%d\n", lock);
SDL_AtomicUnlock(&lock);
printf("AtomicUnlock lock=%d\n", lock);
printf("\natomic -----------------------------------------\n\n");
SDL_AtomicSet(&v, 0);
tfret = SDL_AtomicSet(&v, 10) == 0;
printf("AtomicSet(10) tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
tfret = SDL_AtomicAdd(&v, 10) == 10;
printf("AtomicAdd(10) tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
SDL_AtomicSet(&v, 0);
SDL_AtomicIncRef(&v);
tfret = (SDL_AtomicGet(&v) == 1);
printf("AtomicIncRef() tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
SDL_AtomicIncRef(&v);
tfret = (SDL_AtomicGet(&v) == 2);
printf("AtomicIncRef() tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
tfret = (SDL_AtomicDecRef(&v) == SDL_FALSE);
printf("AtomicDecRef() tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
tfret = (SDL_AtomicDecRef(&v) == SDL_TRUE);
printf("AtomicDecRef() tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
SDL_AtomicSet(&v, 10);
tfret = (SDL_AtomicCAS(&v, 0, 20) == SDL_FALSE);
printf("AtomicCAS() tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
value = SDL_AtomicGet(&v);
tfret = (SDL_AtomicCAS(&v, value, 20) == SDL_TRUE);
printf("AtomicCAS() tfret=%s val=%d\n", tf(tfret), SDL_AtomicGet(&v));
}
void render()
{
//Clear screen
SDL_SetRenderDrawColor(gRenderer, 0xFF, 0xFF, 0xFF, 0xFF);
SDL_RenderClear(gRenderer);
//draw background
//draw background objects
//draw bullets
//draw npcs
//draw player
//draw asteroids/explosions/effects
//draw FPS number (framesThisSecond)
gFPSTextTexture.render((SCREEN_WIDTH - gFPSTextTexture.getWidth())/2, (SCREEN_HEIGHT - gFPSTextTexture.getHeight())/2);
//flip
SDL_RenderPresent(gRenderer);
//Increment frame counter
SDL_AtomicLock( &gDataLock );
countedFrames++;
SDL_AtomicUnlock( &gDataLock );
}
SDL_TLSData *
SDL_Generic_GetTLSData()
{
SDL_threadID thread = SDL_ThreadID();
SDL_TLSEntry *entry;
SDL_TLSData *storage = NULL;
#if !SDL_THREADS_DISABLED
if (!SDL_generic_TLS_mutex) {
static SDL_SpinLock tls_lock;
SDL_AtomicLock(&tls_lock);
if (!SDL_generic_TLS_mutex) {
SDL_mutex *mutex = SDL_CreateMutex();
SDL_MemoryBarrierRelease();
SDL_generic_TLS_mutex = mutex;
if (!SDL_generic_TLS_mutex) {
SDL_AtomicUnlock(&tls_lock);
return NULL;
}
}
SDL_AtomicUnlock(&tls_lock);
}
#endif /* SDL_THREADS_DISABLED */
SDL_MemoryBarrierAcquire();
SDL_LockMutex(SDL_generic_TLS_mutex);
for (entry = SDL_generic_TLS; entry; entry = entry->next) {
if (entry->thread == thread) {
storage = entry->storage;
break;
}
}
#if !SDL_THREADS_DISABLED
SDL_UnlockMutex(SDL_generic_TLS_mutex);
#endif
return storage;
}
SDL_TLSData *
SDL_SYS_GetTLSData()
{
if (thread_local_storage == TLS_OUT_OF_INDEXES && !generic_local_storage) {
static SDL_SpinLock lock;
SDL_AtomicLock(&lock);
if (thread_local_storage == TLS_OUT_OF_INDEXES && !generic_local_storage) {
DWORD storage = TlsAlloc();
if (storage != TLS_OUT_OF_INDEXES) {
SDL_MemoryBarrierRelease();
thread_local_storage = storage;
} else {
generic_local_storage = SDL_TRUE;
}
}
SDL_AtomicUnlock(&lock);
}
if (generic_local_storage) {
return SDL_Generic_GetTLSData();
}
SDL_MemoryBarrierAcquire();
return (SDL_TLSData *)TlsGetValue(thread_local_storage);
}
SDL_TLSData *
SDL_SYS_GetTLSData()
{
if (thread_local_storage == INVALID_PTHREAD_KEY && !generic_local_storage) {
static SDL_SpinLock lock;
SDL_AtomicLock(&lock);
if (thread_local_storage == INVALID_PTHREAD_KEY && !generic_local_storage) {
pthread_key_t storage;
if (pthread_key_create(&storage, NULL) == 0) {
SDL_MemoryBarrierRelease();
thread_local_storage = storage;
} else {
generic_local_storage = SDL_TRUE;
}
}
SDL_AtomicUnlock(&lock);
}
if (generic_local_storage) {
return SDL_Generic_GetTLSData();
}
SDL_MemoryBarrierAcquire();
return (SDL_TLSData *)pthread_getspecific(thread_local_storage);
}
int worker( void* data )
{
printf( "%s starting...\n", data );
//Pre thread random seeding
srand( SDL_GetTicks() );
//Work 5 times
for( int i = 0; i < 5; ++i )
{
//Wait randomly
SDL_Delay( 16 + rand() % 32 );
//Lock
SDL_AtomicLock( &gDataLock );
//Print pre work data
printf( "%s gets %d\n", data, gData );
//"Work"
gData = rand() % 256;
//Print post work data
printf( "%s sets %d\n\n", data, gData );
//Unlock
SDL_AtomicUnlock( &gDataLock );
//Wait randomly
SDL_Delay( 16 + rand() % 640 );
}
printf( "%s finished!\n\n", data );
return 0;
}
SDL_assert_state
SDL_ReportAssertion(SDL_assert_data *data, const char *func, const char *file,
int line)
{
static int assertion_running = 0;
static SDL_SpinLock spinlock = 0;
SDL_assert_state state = SDL_ASSERTION_IGNORE;
SDL_AtomicLock(&spinlock);
if (assertion_mutex == NULL) { /* never called SDL_Init()? */
assertion_mutex = SDL_CreateMutex();
if (assertion_mutex == NULL) {
SDL_AtomicUnlock(&spinlock);
return SDL_ASSERTION_IGNORE; /* oh well, I guess. */
}
}
SDL_AtomicUnlock(&spinlock);
if (SDL_LockMutex(assertion_mutex) < 0) {
return SDL_ASSERTION_IGNORE; /* oh well, I guess. */
}
/* doing this because Visual C is upset over assigning in the macro. */
if (data->trigger_count == 0) {
data->function = func;
data->filename = file;
data->linenum = line;
}
SDL_AddAssertionToReport(data);
assertion_running++;
if (assertion_running > 1) { /* assert during assert! Abort. */
if (assertion_running == 2) {
SDL_AbortAssertion();
} else if (assertion_running == 3) { /* Abort asserted! */
SDL_ExitProcess(42);
} else {
while (1) { /* do nothing but spin; what else can you do?! */ }
}
}
if (!data->always_ignore) {
state = assertion_handler(data, assertion_userdata);
}
switch (state)
{
case SDL_ASSERTION_ABORT:
SDL_AbortAssertion();
return SDL_ASSERTION_IGNORE; /* shouldn't return, but oh well. */
case SDL_ASSERTION_ALWAYS_IGNORE:
state = SDL_ASSERTION_IGNORE;
data->always_ignore = 1;
break;
case SDL_ASSERTION_IGNORE:
case SDL_ASSERTION_RETRY:
case SDL_ASSERTION_BREAK:
break; /* macro handles these. */
}
assertion_running--;
SDL_UnlockMutex(assertion_mutex);
return state;
}
SDL_TimerID
SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *param)
{
SDL_TimerData *data = &SDL_timer_data;
SDL_Timer *timer;
SDL_TimerMap *entry;
if (!data->active) {
int status = 0;
SDL_AtomicLock(&data->lock);
if (!data->active) {
status = SDL_TimerInit();
}
SDL_AtomicUnlock(&data->lock);
if (status < 0) {
return 0;
}
}
SDL_AtomicLock(&data->lock);
timer = data->freelist;
if (timer) {
data->freelist = timer->next;
}
SDL_AtomicUnlock(&data->lock);
if (timer) {
SDL_RemoveTimer(timer->timerID);
} else {
timer = (SDL_Timer *)SDL_malloc(sizeof(*timer));
if (!timer) {
SDL_OutOfMemory();
return 0;
}
}
timer->timerID = SDL_AtomicIncRef(&data->nextID);
timer->callback = callback;
timer->param = param;
timer->interval = interval;
timer->scheduled = SDL_GetTicks() + interval;
timer->canceled = SDL_FALSE;
entry = (SDL_TimerMap *)SDL_malloc(sizeof(*entry));
if (!entry) {
SDL_free(timer);
SDL_OutOfMemory();
return 0;
}
entry->timer = timer;
entry->timerID = timer->timerID;
SDL_mutexP(data->timermap_lock);
entry->next = data->timermap;
data->timermap = entry;
SDL_mutexV(data->timermap_lock);
/* Add the timer to the pending list for the timer thread */
SDL_AtomicLock(&data->lock);
timer->next = data->pending;
data->pending = timer;
SDL_AtomicUnlock(&data->lock);
/* Wake up the timer thread if necessary */
SDL_SemPost(data->sem);
return entry->timerID;
}
static int
SDL_TimerThread(void *_data)
{
SDL_TimerData *data = (SDL_TimerData *)_data;
SDL_Timer *pending;
SDL_Timer *current;
SDL_Timer *freelist_head = NULL;
SDL_Timer *freelist_tail = NULL;
Uint32 tick, now, interval, delay;
/* Threaded timer loop:
* 1. Queue timers added by other threads
* 2. Handle any timers that should dispatch this cycle
* 3. Wait until next dispatch time or new timer arrives
*/
for ( ; ; ) {
/* Pending and freelist maintenance */
SDL_AtomicLock(&data->lock);
{
/* Get any timers ready to be queued */
pending = data->pending;
data->pending = NULL;
/* Make any unused timer structures available */
if (freelist_head) {
freelist_tail->next = data->freelist;
data->freelist = freelist_head;
}
}
SDL_AtomicUnlock(&data->lock);
/* Sort the pending timers into our list */
while (pending) {
current = pending;
pending = pending->next;
SDL_AddTimerInternal(data, current);
}
freelist_head = NULL;
freelist_tail = NULL;
/* Check to see if we're still running, after maintenance */
if (!data->active) {
break;
}
/* Initial delay if there are no timers */
delay = SDL_MUTEX_MAXWAIT;
tick = SDL_GetTicks();
/* Process all the pending timers for this tick */
while (data->timers) {
current = data->timers;
if ((Sint32)(tick-current->scheduled) < 0) {
/* Scheduled for the future, wait a bit */
delay = (current->scheduled - tick);
break;
}
/* We're going to do something with this timer */
data->timers = current->next;
if (current->canceled) {
interval = 0;
} else {
interval = current->callback(current->interval, current->param);
}
if (interval > 0) {
/* Reschedule this timer */
current->scheduled = tick + interval;
SDL_AddTimerInternal(data, current);
} else {
if (!freelist_head) {
freelist_head = current;
}
if (freelist_tail) {
freelist_tail->next = current;
}
freelist_tail = current;
current->canceled = SDL_TRUE;
}
}
/* Adjust the delay based on processing time */
now = SDL_GetTicks();
interval = (now - tick);
if (interval > delay) {
delay = 0;
} else {
delay -= interval;
}
/* Note that each time a timer is added, this will return
immediately, but we process the timers added all at once.
That's okay, it just means we run through the loop a few
extra times.
*/
SDL_SemWaitTimeout(data->sem, delay);
}
return 0;
}
void fe_mt_spinlock_lock (fe_mt_spinlock *spinlock) {
SDL_AtomicLock(spinlock);
}
int main( int argc, char* args[] )
{
//The window being rendered to
SDL_Window* window = NULL;
//THe surface contained by the window
SDL_Surface* screenSurface = NULL;
//Initialize SDL
if( SDL_Init( SDL_INIT_VIDEO ) < 0 )
{
printf( "SDL could not initialize! SDL_Error: %s\n", SDL_GetError() );
}
else
{
//Create window
window = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN );
if( window == NULL)
{
printf( "Window could not be created! SDL_Error: %s\n", SDL_GetError() );
}
else
{
//Get window surface
screenSurface= SDL_GetWindowSurface( window );
//Fill the surface white
SDL_FillRect( screenSurface, NULL, SDL_MapRGB( screenSurface->format, 0xFF, 0xFF, 0xFF ) );
//Update the surface
SDL_UpdateWindowSurface( window );
//Wait 2 seconds
SDL_Delay(2000);
}
}
quit = false;
countedFrames = 0;
framesThisSecond = 0;
//Start fps counting thread
SDL_Thread* fpsThread = SDL_CreateThread(fpsworker, "FPSThread", NULL);
//FPS text
std::stringstream timeText;
SDL_Color fpsColor = {0,0,0,255};
#MAIN GAME LOOP
SDL_AtomicLock( &gDataLock );
bool mainquit = quit;
SDL_AtomicUnlock( &gDataLock );
while(!mainquit)
{
//Get/process input from user
processInput();
//Make all input-independent updates (game world, physics, AI, etc)
update();
//Draw world + objects
render();
//Delay (goal: 120 fps with vsync)
delay();
}
SDL_WaitThread(fpsThread, NULL);
//Destroy window
SDL_DestroyWindow( window );
//Quit SDL subsystems
SDL_Quit();
return 0;
}