//---------------------------------------------------------------------------
// ebxa.cpp
//---------------------------------------------------------------------------

#include <windows.h>

#define BLOCKSIZE (128)
#define BLOCKS_PER_SECTOR (18)


#pragma argsused
int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved)
{
	return 1;
}
//---------------------------------------------------------------------------

extern "C" __declspec(dllexport) void __stdcall ebxa(char* file, int start, int len);
extern "C" __declspec(dllexport) int __stdcall wave_length(int start, int len);
extern "C" __declspec(dllexport) bool __stdcall ebxa2wave(char* file, char* pvWaveData, int start, int
len);

HANDLE file_open(char* file);
int file_seek(HANDLE hFile, unsigned long offset);
int file_read(HANDLE hFile, unsigned char* buffer, int size);
void XADecode(char* &wavep,char* sbuf,int& y,int& z);

// play EB-XA sound data
void __stdcall ebxa(char* file, int start, int len)
{
	char* pvWaveData = new char[wave_length(start, len)];
	if (ebxa2wave(file, pvWaveData, start, len))
    	PlaySound((LPCSTR)pvWaveData, NULL, SND_MEMORY | SND_SYNC);
    delete [] pvWaveData;
}

// necessary memory length for wave data
int __stdcall wave_length(int start, int length)
{
   	return 8 * 28 * 2 * 18 * ((length + 15) / 16) + 44;
}

// convert EBXA data to wave data
bool __stdcall ebxa2wave(char* file, char* pvWaveData, int start, int len)
{
    int end = start + len - 1;
	// length of wave data
   	int length = 8 * 28 * 2 * 18 * (((end - start) >> 4) + 1);

    HANDLE sound = file_open(file);
    if (sound == NULL)
    	return false;

	unsigned char buf[BLOCKSIZE];
	// Write WAV Header
    // RIFF chunk ID
	strncpy(pvWaveData, "RIFF", 4);
    // chunk size  �@Data + Header Length
    *((long *)&pvWaveData[4]) = length + 36;
    // WAVE header
	strncpy(pvWaveData + 8, "WAVE", 4);
    // fmt chunk ID
    strncpy(pvWaveData + 12, "fmt ", 4);
    // chunk size  16 bytes
    *((long *)&pvWaveData[16]) = 16;
    // format ID�F 1= real PCM
	*((short *)&pvWaveData[20]) = 1;
	// channels  1= monoral
    *((short *)&pvWaveData[22]) = 1;
    // sampling rate
	*((long *)&pvWaveData[24]) = 18900;
    // transfer rate
    // bytesPerSec = sampling_rate * unit_size
	*((long *)&pvWaveData[28]) = 18900 * 2;
    // unit size (bytes)
    //   (channels * bits_per_1_sample) / 8
	*((short *)&pvWaveData[32]) = 2;
    // bits per 1 sample
    //   8 or 16 bits
	*((short *)&pvWaveData[34]) = 16;
    // data chunk ID
	strncpy(pvWaveData + 36, "data", 4);
    // size of wave data
	*((long *)&pvWaveData[40]) = length;
    char* wavep = pvWaveData + 44;

    // decode EB-XA data
	int y = 0, z = 0;
	for (int lba = start; lba <= end ; lba += 16) {
		file_seek(sound, lba * 0x930 + 0x44);
  		for (int i = 0; i < BLOCKS_PER_SECTOR; i++) {
			file_read(sound, buf, BLOCKSIZE);
    		XADecode(wavep, buf, y, z);
		}
	}

	// close sound file
   	CloseHandle(sound);
	return true;
}

HANDLE file_open(char* file)
{
	SetErrorMode(1);
    HANDLE hFileIndex = CreateFile(file, GENERIC_READ,
							FILE_SHARE_READ, NULL,
							OPEN_EXISTING,
							0, 0);

    SetErrorMode(0);
    if (hFileIndex == (HANDLE)-1)
    	return NULL;
    return hFileIndex;
}

int file_seek(HANDLE hFile, unsigned long offset)
{
	DWORD dwPointer = SetFilePointer(hFile,
						offset, NULL, FILE_BEGIN);
	if (dwPointer == 0xFFFFFFFF) {
		return -1;
	}
    return 0;
}

int file_read(HANDLE hFile, unsigned char* buffer, int size)
{
	unsigned long nBytesRead;
	ReadFile(hFile, buffer, size, &nBytesRead, NULL) ;
	return nBytesRead;
}

// decode EB-XA data
void XADecode(char* &wavep,char* sbuf,int& y,int& z){
  const int k0[4]={0,0xf0,0x1cc,0x188};
  const int k1[4]={0,0,-0xd0,-0xdc};
  int x;
  unsigned char* ubuf=reinterpret_cast<unsigned char*>(sbuf);
  for(int i=0;i<8;i++){
    int r=12-(ubuf[i+4]&15);
    int f=(ubuf[i+4]>>4)&15;
    for(int j=0;j<28;j++){
      x=ubuf[i/2+j*4+16];
      if (i&1) x>>=4;
      x&=15;
      if (x>=8) x-=16;
      x<<=r;
      x+=(y*k0[f]+z*k1[f])/256;
      if (x<-0x8000) x=-0x8000;
      if (x>0x7fff) x=0x7fff;
      *wavep++ = x & 255;
      *wavep++ = ((0xff00 & x) >> 8)&255;
      z=y;
      y=x;
    }
  }
}