#include<windows.h>
#include"waveOutSetPosition.h"

void SetPositionUnprepareHeader(HWAVEOUT hwo);

static WAVEHDR g_whdr;

int waveOutSetPosition(HWAVEOUT hwo,LPWAVEHDR pwh,LPMMTIME pmmt,WOSP *wosp)
{
	DWORD cb;
	switch(pmmt->wType){
		case TIME_BYTES:
			cb=pmmt->u.cb;
			break;
		case TIME_SAMPLES:
			cb=pmmt->u.sample * wosp->nBlockAlign;
			break;
		case TIME_MS:
			cb=pmmt->u.ms * wosp->nAvgBytesPerSec / 1000;
			break;
		default:
			return -1;
	}
	if(cb % wosp->nBlockAlign){
		if((cb % wosp->nBlockAlign) <= (wosp->nBlockAlign / 2)){
			cb-=(cb % wosp->nBlockAlign);
		}else{
			cb+=(wosp->nBlockAlign - (cb % wosp->nBlockAlign));
		}
	}
	if(cb<0 || cb >= pwh->dwBufferLength) return -2;

	waveOutReset(hwo);
	SetPositionUnprepareHeader(hwo);

	ZeroMemory(&g_whdr,sizeof(WAVEHDR));
	g_whdr.lpData=pwh->lpData + cb;
	g_whdr.dwBufferLength=pwh->dwBufferLength - cb;
	g_whdr.dwFlags=WHDR_BEGINLOOP | WHDR_ENDLOOP;
	g_whdr.dwLoops=1;

	waveOutPrepareHeader(hwo,&g_whdr,sizeof(WAVEHDR));
	waveOutWrite(hwo,&g_whdr,sizeof(WAVEHDR));
	return 0;
}

void SetPositionUnprepareHeader(HWAVEOUT hwo)
{
	if(g_whdr.dwFlags & WHDR_PREPARED){
		waveOutUnprepareHeader(hwo,&g_whdr,sizeof(WAVEHDR));
	}
}