#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <Windows.h>
#include <MMSystem.h>

void fill(char *data)
{
	for (int i = 0; i < 4096; i++)
	{
		data[i] = (i & (i & 512 ? 7 : 3)) << 3;
	}
}

static const WAVEFORMATEX fmt = {
	WAVE_FORMAT_PCM, 1, 8000, 8000, 1, 8, 0
};

int main(int argc, char *argv[])
{
	HWAVEOUT out;
	HRESULT rc = waveOutOpen(&out, WAVE_MAPPER, &fmt, NULL, NULL, CALLBACK_NULL);
	if (rc != MMSYSERR_NOERROR)
	{
		printf("error %d on open\n");
		exit(1);
	}

	WAVEHDR bufs[2] = {
		{ (char *)malloc(4096), 4096 },
		{ (char *)malloc(4096), 4096 },
	};
	int i = 0;

	fill(bufs[i].lpData);
	bufs[i].dwFlags = WHDR_PREPARED;
	waveOutPrepareHeader(out, bufs + i, sizeof(WAVEHDR));
	waveOutWrite(out, bufs + i, sizeof(WAVEHDR));
	i ^= 1;

	while (!(GetAsyncKeyState(VK_ESCAPE) & 1))
	{
		fill(bufs[i].lpData);
		bufs[i].dwFlags = WHDR_PREPARED;
		waveOutPrepareHeader(out, bufs + i, sizeof(WAVEHDR));
		waveOutWrite(out, bufs + i, sizeof(WAVEHDR));
		i ^= 1;
		while (waveOutUnprepareHeader(out, bufs + i, sizeof(WAVEHDR)) == WAVERR_STILLPLAYING);
	}
}