aiie/sdl/sdl-speaker.cpp

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#include "sdl-speaker.h"
#include <pthread.h>
extern "C"
{
#include <SDL.h>
#include <SDL_thread.h>
};
#include "timeutil.h"
// FIXME: Globals; ick.
static pthread_t speakerThreadID;
static uint8_t curSpeakerData = 0x00;
static volatile uint16_t bufIdx = 0;
static uint8_t soundBuf[4096];
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static uint64_t hitcount;
static uint64_t misscount;
static uint64_t copycount = 0;
static void audioCallback(void *unused, Uint8 *stream, int len)
{
pthread_mutex_lock(&mutex);
if (bufIdx >= len) {
memcpy(stream, soundBuf, len);
if (bufIdx > len) {
// move the remaining data down
memcpy(soundBuf, &soundBuf[len], bufIdx - len);
bufIdx -= len;
copycount += len;
}
} else {
// Audio underrun
memset(stream, 0, len);
}
pthread_mutex_unlock(&mutex);
}
static void *speaker_thread(void *dummyptr) {
struct timespec currentTime;
struct timespec startTime;
struct timespec nextSampleTime;
pthread_mutex_init(&mutex, NULL);
SDL_AudioSpec audioDevice;
SDL_AudioSpec audioActual;
SDL_memset(&audioDevice, 0, sizeof(audioDevice));
audioDevice.freq = 22050;
audioDevice.format = AUDIO_U8;
audioDevice.channels = 1;
audioDevice.samples = 2048; // 2048 bytes @ 22050Hz is about 1/10th second out of sync - should be okay for this testing
audioDevice.callback = audioCallback;
audioDevice.userdata = NULL;
SDL_OpenAudio(&audioDevice, &audioActual); // FIXME retval
printf("Actual: freq %d channels %d samples %d\n",
audioActual.freq, audioActual.channels, audioActual.samples);
_init_darwin_shim();
do_gettime(&startTime);
do_gettime(&nextSampleTime);
SDL_PauseAudio(0);
uint64_t sampleCount = 0;
while (1) {
do_gettime(&currentTime);
struct timespec diff = tsSubtract(nextSampleTime, currentTime);
if (diff.tv_sec >= 0 && diff.tv_nsec >= 0) {
nanosleep(&diff, NULL);
hitcount++;
} else
misscount++;
if ((sampleCount & 0xFFFF) == 0) {
printf("sound hit: %lld miss: %lld copy: %lld\n", hitcount, misscount, copycount);
}
pthread_mutex_lock(&mutex);
soundBuf[bufIdx++] = curSpeakerData & 0xFF;
if (bufIdx >= sizeof(soundBuf)) {
// Audio overrun; start dropping data
bufIdx--;
}
pthread_mutex_unlock(&mutex);
// set nextSampleTime to the absolute reference time of when the
// next sample should start (based on our start time).
timespec_add_us(&startTime, (sampleCount * 1000000) / 22050 , &nextSampleTime);
sampleCount++;
}
}
SDLSpeaker::SDLSpeaker()
{
toggleState = false;
needsToggle = false;
mixerValue = 0;
_init_darwin_shim(); // set up the clock interface
if (!pthread_create(&speakerThreadID, NULL, &speaker_thread, (void *)NULL)) {
printf("speaker thread created\n");
}
}
SDLSpeaker::~SDLSpeaker()
{
pclose(f);
}
void SDLSpeaker::toggle()
{
needsToggle = true;
}
void SDLSpeaker::maintainSpeaker(uint32_t c)
{
if (needsToggle) {
// Override the mixer with a 1-bit "Terribad" audio sample change
toggleState = !toggleState;
needsToggle = false;
}
// The "terribad" audio gets two shares. THis means we've got 8 total
// "voices" -- 6 from the mockingboard and 2 from the built-in. 8 is
// a great number for dividing. :)
mixerValue += (toggleState ? 0xFF : 0x00);
numMixed += 2;
#if DEBUGGING
if (numMixed != 8) {
printf("SPEAKER FAIL - should always be 8\n");
}
#endif
mixerValue >>= 3; // divide by 8
curSpeakerData = mixerValue & 0xFF;
}
void SDLSpeaker::beginMixing()
{
mixerValue = 0;
numMixed = 0;
}
void SDLSpeaker::mixOutput(uint8_t v)
{
mixerValue += v;
numMixed++;
}