#include<windows.h>

// winmm.lib をリンクする
#pragma comment(lib,"winmm")

#define SRATE	8000	//標本化周波数(1秒間のサンプル数)
#define F		400		//周波数(1秒間の波形数)

LRESULT CALLBACK WindowProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	WAVEFORMATEX wfe;
	static HWAVEOUT hWaveOut;
	static WAVEHDR whdr;
	static LPBYTE lpWave;
	int i,len;
	double d;

	switch(uMsg){
		case WM_CREATE:
			wfe.wFormatTag=WAVE_FORMAT_PCM;
			wfe.nChannels=1;	//モノラル
			wfe.wBitsPerSample=8;	//量子化ビット数
			wfe.nBlockAlign=wfe.nChannels * wfe.wBitsPerSample/8;
			wfe.nSamplesPerSec=SRATE;	//標本化周波数
			wfe.nAvgBytesPerSec=wfe.nSamplesPerSec * wfe.nBlockAlign;

			waveOutOpen(&hWaveOut,WAVE_MAPPER,&wfe,0,0,CALLBACK_NULL);

			lpWave=(LPBYTE)calloc(wfe.nAvgBytesPerSec,2);	//2秒分

			len=SRATE/F;	//波長
			d=255.0/(len-1);
			for(i=0;i<SRATE*2;i++){	//波形データ作成
				lpWave[i]=(BYTE)(d*(i%len));
			}

			whdr.lpData=(LPSTR)lpWave;
			whdr.dwBufferLength=wfe.nAvgBytesPerSec * 2;
			whdr.dwFlags=WHDR_BEGINLOOP | WHDR_ENDLOOP;
			whdr.dwLoops=1;

			waveOutPrepareHeader(hWaveOut,&whdr,sizeof(WAVEHDR));
			waveOutWrite(hWaveOut,&whdr,sizeof(WAVEHDR));
			return 0;
		case WM_DESTROY:
			waveOutReset(hWaveOut);
			waveOutUnprepareHeader(hWaveOut,&whdr,sizeof(WAVEHDR));
			waveOutClose(hWaveOut);
			free(lpWave);
			PostQuitMessage(0);
			return 0;
	}
	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(
	HINSTANCE hInstance,HINSTANCE hPrevInstance,PSTR lpCmdLine,int nCmdShow)
{
	WNDCLASS wc;
	MSG msg;

	wc.style		 = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc	 = WindowProc;
	wc.cbClsExtra	 = 0;
	wc.cbWndExtra	 = 0;
	wc.hInstance	 = hInstance;
	wc.hIcon		 = LoadIcon(NULL,IDI_APPLICATION);
	wc.hCursor		 = LoadCursor(NULL,IDC_ARROW);
	wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wc.lpszMenuName	 = NULL;
	wc.lpszClassName = __FILE__;
	if(!RegisterClass(&wc)) return 0;

	HWND hWnd=CreateWindow(
		__FILE__,"WAVEデータ作成＆再生(8ビットノコギリ波)",
		WS_OVERLAPPEDWINDOW | WS_VISIBLE,
		CW_USEDEFAULT,CW_USEDEFAULT,
		CW_USEDEFAULT,CW_USEDEFAULT, 
		NULL,NULL,hInstance,NULL);
	if(hWnd==NULL) return 0;

	BOOL bRet;
	while((bRet=GetMessage(&msg,NULL,0,0))!=0){
		if(bRet==-1) break;
		DispatchMessage(&msg);
	}

	return (int)msg.wParam;
}