static void OPL_AdvanceTime(unsigned int nsamples)
{
opl_callback_t callback;
void *callback_data;
// Advance time.
current_time += nsamples;
if (opl_paused)
{
pause_offset += nsamples;
}
// Are there callbacks to invoke now? Keep invoking them
// until there are none more left.
while (!OPL_Queue_IsEmpty(callback_queue)
&& current_time >= OPL_Queue_Peek(callback_queue) + pause_offset)
{
// Pop the callback from the queue to invoke it.
if (!OPL_Queue_Pop(callback_queue, &callback, &callback_data))
{
break;
}
callback(callback_data);
}
}
static int CallbackWaiting(uint64_t *next_time)
{
// If paused, just wait in 50ms increments until unpaused.
// Update pause_offset so after we unpause, the callback
// times will be right.
if (opl_timer_paused)
{
*next_time = current_time + 50 * OPL_MS;
pause_offset += 50 * OPL_MS;
return 0;
}
// If there are no queued callbacks, sleep for 50ms at a time
// until a callback is added.
if (OPL_Queue_IsEmpty(callback_queue))
{
*next_time = current_time + 50 * OPL_MS;
return 0;
}
// Read the time of the first callback in the queue.
// If the time for the callback has not yet arrived,
// we must sleep until the callback time.
*next_time = OPL_Queue_Peek(callback_queue) + pause_offset;
return *next_time <= current_time;
}
static void OPL_Mix_Callback(void *udata,
Uint8 *byte_buffer,
int buffer_bytes)
{
int16_t *buffer;
unsigned int buffer_len;
unsigned int filled = 0;
// Buffer length in samples (quadrupled, because of 16-bit and stereo)
buffer = (int16_t *) byte_buffer;
buffer_len = buffer_bytes / 4;
// Repeatedly call the OPL emulator update function until the buffer is
// full.
while (filled < buffer_len)
{
uint64_t next_callback_time;
uint64_t nsamples;
SDL_LockMutex(callback_queue_mutex);
// Work out the time until the next callback waiting in
// the callback queue must be invoked. We can then fill the
// buffer with this many samples.
if (opl_sdl_paused || OPL_Queue_IsEmpty(callback_queue))
{
nsamples = buffer_len - filled;
}
else
{
next_callback_time = OPL_Queue_Peek(callback_queue) + pause_offset;
nsamples = (next_callback_time - current_time) * mixing_freq;
nsamples = (nsamples + OPL_SECOND - 1) / OPL_SECOND;
if (nsamples > buffer_len - filled)
{
nsamples = buffer_len - filled;
}
}
SDL_UnlockMutex(callback_queue_mutex);
// Add emulator output to buffer.
FillBuffer(buffer + filled * 2, nsamples);
filled += nsamples;
// Invoke callbacks for this point in time.
AdvanceTime(nsamples);
}
}
void OPL_Render_Samples(void *dest, unsigned buffer_len)
{
unsigned int filled = 0;
short *buffer = (short *)dest;
// Repeatedly call the OPL emulator update function until the buffer is
// full.
while (filled < buffer_len)
{
unsigned int next_callback_time;
unsigned int nsamples;
// Work out the time until the next callback waiting in
// the callback queue must be invoked. We can then fill the
// buffer with this many samples.
if (opl_paused || OPL_Queue_IsEmpty(callback_queue))
{
nsamples = buffer_len - filled;
}
else
{
next_callback_time = OPL_Queue_Peek(callback_queue) + pause_offset;
nsamples = next_callback_time - current_time;
if (nsamples > buffer_len - filled)
{
nsamples = buffer_len - filled;
}
}
// Add emulator output to buffer.
#ifdef STEREO
FillBuffer(buffer + filled * 2, nsamples);
#else
FillBuffer(buffer + filled, nsamples);
#endif
filled += nsamples;
// Invoke callbacks for this point in time.
OPL_AdvanceTime(nsamples);
}
}
int main()
{
opl_callback_queue_t *queue;
int iteration;
queue = OPL_Queue_Create();
for (iteration=0; iteration<5000; ++iteration)
{
opl_callback_t callback;
void *data;
unsigned int time;
unsigned int newtime;
int i;
for (i=0; i<MAX_OPL_QUEUE; ++i)
{
time = rand() % 0x10000;
OPL_Queue_Push(queue, NULL, NULL, time);
}
time = 0;
for (i=0; i<MAX_OPL_QUEUE; ++i)
{
assert(!OPL_Queue_IsEmpty(queue));
newtime = OPL_Queue_Peek(queue);
assert(OPL_Queue_Pop(queue, &callback, &data));
assert(newtime >= time);
time = newtime;
}
assert(OPL_Queue_IsEmpty(queue));
assert(!OPL_Queue_Pop(queue, &callback, &data));
}
}
static void AdvanceTime(unsigned int nsamples)
{
opl_callback_t callback;
void *callback_data;
uint64_t us;
SDL_LockMutex(callback_queue_mutex);
// Advance time.
us = ((uint64_t) nsamples * OPL_SECOND) / mixing_freq;
current_time += us;
if (opl_sdl_paused)
{
pause_offset += us;
}
// Are there callbacks to invoke now? Keep invoking them
// until there are no more left.
while (!OPL_Queue_IsEmpty(callback_queue)
&& current_time >= OPL_Queue_Peek(callback_queue) + pause_offset)
{
// Pop the callback from the queue to invoke it.
if (!OPL_Queue_Pop(callback_queue, &callback, &callback_data))
{
break;
}
// The mutex stuff here is a bit complicated. We must
// hold callback_mutex when we invoke the callback (so that
// the control thread can use OPL_Lock() to prevent callbacks
// from being invoked), but we must not be holding
// callback_queue_mutex, as the callback must be able to
// call OPL_SetCallback to schedule new callbacks.
SDL_UnlockMutex(callback_queue_mutex);
SDL_LockMutex(callback_mutex);
callback(callback_data);
SDL_UnlockMutex(callback_mutex);
SDL_LockMutex(callback_queue_mutex);
}
SDL_UnlockMutex(callback_queue_mutex);
}
