usim

// MMcM: It's the number of microseconds between triggers of the
//   flip-flop.  That is, half the wavelength.  So the frequency is, I
//   think, (/ 1e6 (* #o1350 2)).  So I guess 672Hz. And duration is
//   only .13sec.
#if WITH_X11
		x11_beep();
#elif WITH_SDL2
		sdl2_beep(-1);
#else
		fprintf(stderr, "\a");	/* Beep! */
#endif
		break;
	case 0112:
		*pv = iob_csr;
		INFO(TRACE_IOB | TRACE_UNIBUS, "unibus: kbd csr %011o\n", *pv);

		 * Triggered via %BEEP.
		 */
#if WITH_X11
		x11_beep();
#elif WITH_SDL1
		sdl1_beep();
#elif WITH_SDL2
		sdl2_beep(v);
#else
		fprintf(stderr, "\a");	/* Beep! */
#endif
		break;
	case 0112:
		INFO(TRACE_IOB | TRACE_UNIBUS, "unibus: kbd csr\n");
		iob_csr = (iob_csr & ~017) | (v & 017);

			break;
		case SDL_QUIT:
			exit(0);
			break;
		}
	}
}

float xbeep_volume = 1.0f;
int AMPLITUDE = 28000;
const int SAMPLE_RATE = 44100;

int xbeep_sample_nr = 0;
float xbeep_freq = 0.0f;

void xbeep_audio_callback(void *user_data, Uint8 *raw_buffer, int bytes)
{
    Sint16 *buffer = (Sint16*)raw_buffer;
    int length = bytes / 2; // 2 bytes per sample for AUDIO_S16SYS
    float *freq = (float *)(user_data);
    int amp = AMPLITUDE * xbeep_volume;

    for(int i = 0; i < length; i++, xbeep_sample_nr++) {
        double time = (double)xbeep_sample_nr / (double)SAMPLE_RATE;
        buffer[i] = (Sint16)(amp * sin(2.0f * M_PI * (*freq) * time)); // render sine wave
    }
}

void xbeep_audio_init() {
  SDL_AudioSpec want;
  SDL_AudioSpec have;

  want.freq = SAMPLE_RATE; 
  want.format = AUDIO_S16SYS; 
  want.channels = 1; 
  want.samples = 2048; 
  want.callback = xbeep_audio_callback; 
  want.userdata = &xbeep_freq; 
  if(SDL_OpenAudio(&want, &have) != 0) SDL_LogError(SDL_LOG_CATEGORY_AUDIO, "Failed to open audio: %s", SDL_GetError());
  if(want.format != have.format) SDL_LogError(SDL_LOG_CATEGORY_AUDIO, "Failed to get the desired AudioSpec");
  SDL_PauseAudio(1);
}

void xbeep_audio_close() {
  SDL_CloseAudio();
}

void xbeep(int halfwavelength, int duration) {
  xbeep_freq = 1000000.0f / (float)(halfwavelength*2);
  xbeep_sample_nr = 0;

  SDL_PauseAudio(0); 
  SDL_Delay(duration/1000); 
  SDL_PauseAudio(1); 
}

void
sdl2_beep(int v)
{
///XBEEP (MISC-INST-ENTRY %BEEP)
///;;; First argument is half-wavelength, second is duration.  Both are in microseconds.
///;;; M-1 has 2nd argument (duration) which is added to initial time-check
///;;; M-2 contains most recent time check
///;;;     to compute quitting time
///;;; M-C contains 1st argument, the wavelength
///;;; M-4 contains the time at which the next click must be done.
///;;; Note that the 32-bit clock wraps around once an hour, we have to be careful
///;;; to compare clock values in the correct way, namely without overflow checking. 
extern uint32_t mmem[32];
#define DTP_FIX_VAL(x) ((x) & ((1 << 24) - 1))
#define DTP_FIX(x) (DTP_FIX_VAL(x) | 5 << 25)
 int wavelength = DTP_FIX_VAL(mmem[7]);//M-C M-MEM 7
 int duration = DTP_FIX_VAL(mmem[22]);//M-1 M-MEM 22
	xbeep(wavelength, duration);
}

void
sdl2_init(void)
{
	NOTICE(TRACE_USIM, "tv: using SDL backend for monitor and keyboard\n");

	Foreground = 0xffffff; // White
	Background = 0x000000; // Black

	xbeep_audio_init();	
	SDL_CreateWindowAndRenderer(tv_width, tv_height, SDL_WINDOW_OPENGL, &window, &renderer);

	SDL_ShowCursor(0);	/* Invisible cursor. */

//	SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
//	SDL_RenderClear(renderer);
//	SDL_RenderPresent(renderer);

	SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");  // make the scaled rendering look smoother.