global buffer or passing by reference?

[khan]

Create a class for the global data buffer. Put it in a separate header file. class CGlobalData { static [DATA_TYPE_HERE] m_Data; }; Then use it as: CGlobalData::m_Data; this is this.

[billiam904]

I did as you suggested and am etting the following error: c:\development\c-tools\Classes\WavWrite.cpp(79): error C2248: 'CReadDemoWave::testinteger' : cannot access private member declared in class 'CReadDemoWave' I need to be able to access this data from three separate .cpp files. Here's my 'h: \ class CReadDemoWave { static int testinteger; public: void ReadDemoWave(); void ReadDemoIntoBuffer(); void PlayWav(); long QueueWaveData(HWAVEOUT HWaveOut, WAVEHDR * waveHeader, DWORD WaveDataPlayed, DWORD WaveBufSize, HMMIO HMmio); LPSTR *GetDemoBuffer(void); void WriteDemo(HMMIO recordHandle); WAVEHDR lpDemoData; DWORD dwDemoDataSize; int m_nDemoBufferSize; BYTE* m_pbyDemoBuffer; HMMIO m_hmmio; }; I am including the .h in all three .cpp files. Am I doing something wrong? Bill Dennis Orlando, FL

[khan]

Sorry about that. You need to make the variable public. By default it is private. Just write public: before the variable declaration in the class. Like: class CSomething { public: //this needs to be inserted. static DATA_TYPE m_Data; }; this is this.

[Achim Klein]

Hi, in my opinion it is always worth an attempt to get around global data. Maybe this design pattern (Visitor) can help you. The class that can read wave files:

class IveGotTheData
{
public:

// add some 'Getter' methods here

bool ReadWaveFile(const char* Path);

void UseMyData(IknowTheAlgorithm& Operator)
{
Operator.Operate(this);
}
};

The base class for all algorithms that modify your wave data (the Visitor):

class IknowTheAlgorithm
{
public:

virtual void Operate(IveGotTheData* Data) = 0;
};

Your first algorithm is encapsulated in this class:

class Algorithm1 : public IknowTheAlgorithm
{
public:

virtual void Operate(IveGotTheData* Data)
{
// your first algorithm goes here
}
};

Your second algorithm is encapsulated in this class:

class Algorithm2 : public IknowTheAlgorithm
{
public:

virtual void Operate(IveGotTheData* Data)
{
// your second algorithm goes here
}
};

Using your algorithms looks like this:

void main()
{
IveGotTheData wav;

if (wav.ReadWaveFile("Test.wav"))
{
Algorithm1 alg1;
Algorithm2 alg2;

  wav.UseMyData(alg1);
  wav.UseMyData(alg2);

}
}

Regards Achim Klein

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We can do no great things, only small things with great love. - Mother Theresa

[billiam904]

This would be good if it were a new system or code already written in this fashion but I am modifying someone else's code, so I can';t totally rewrite the program. But, thanks. Bill Dennis Orlando, FL

[billiam904]

I'm sorry but now I get the following message: Single error LNK2001: unresolved external symbol "public: static int CReadDemoWave::testinteger" (?testinteger@CReadDemoWave@@2HA) Here is my .h: #include #include #include #define ERROR_LENGTH 1024 class CReadDemoWave { public: static int testinteger; void ReadDemoWave(); void ReadDemoIntoBuffer(); void PlayWav(); long QueueWaveData(HWAVEOUT HWaveOut, WAVEHDR * waveHeader, DWORD WaveDataPlayed, DWORD WaveBufSize, HMMIO HMmio); LPSTR *GetDemoBuffer(void); void WriteDemo(HMMIO recordHandle); // =========== D == E == M == O ======================= // BD create demo buffer. WAVEHDR lpDemoData; DWORD dwDemoDataSize; int m_nDemoBufferSize; BYTE* m_pbyDemoBuffer; HMMIO m_hmmio; //HMMIO hmmio; char m_szError[ERROR_LENGTH]; int m_nError; MMIOINFO m_mmioInfo; DWORD dwDataSize; DWORD dwCount; HPSTR m_hptr; int m_nBufferSize; }; Bill Dennis Orlando, FL

[Achim Klein]

Hi, the problem here is that the definition is missing. Guess your header file (ReadDemoWave.h) looks like this:

class CReadDemoWave
{
public:

// Construction

// Getter methods

// Setter methods

private:

// Attributes

static int m_anyInt; // this is just a declaration
};

Then you have to add the definition of m_anyInt to your cpp file:

#include "ReadDemoWave.h"

// define your static attributes
int CReadDemoWave::m_anyInt;

CReadDemoWave::CReadDemoWave()
{
// your constructor code
}

// Getter methods

// Setter methods

Regards Achim Klein

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We can do no great things, only small things with great love. - Mother Theresa

[Achim Klein]

Hi, could you post the three header files, please ? Maybe <pre> code </pre> is useful.

---

We can do no great things, only small things with great love. - Mother Theresa

[billiam904]

////////////////////////////////////////////////////////////////////// // WavWrite.h: interface for the CWavWrite class. #if !defined(AFX_WAVWRITE_H__2C400A28_DDC3_11D0_9FD3_444553540001__INCLUDED_) #define AFX_WAVWRITE_H__2C400A28_DDC3_11D0_9FD3_444553540001__INCLUDED_ #if _MSC_VER >= 1000 #pragma once #endif // _MSC_VER >= 1000 #include #include #include //#include "readdemowave.h" #define ERROR_LENGTH 1024 //CReadDemoWave cReadDemo; //static DWORD dwDemoDataSize; //WAVEHDR lpDemoData; //static WAVEHDR lpDemoData; /* Definition from MS typedef struct { WORD wFormatTag; WORD nChannels; DWORD nSamplesPerSec; DWORD nAvgBytesPerSec; WORD nBlockAlign; WORD wBitsPerSample; WORD cbSize; } WAVEFORMATEX; typedef struct { FOURCC ckid; DWORD cksize; FOURCC fccType; DWORD dwDataOffset; DWORD dwFlags; } MMCKINFO; */ class CWavWrite { private: char m_szName[FILENAME_MAX]; HMMIO m_hmmioFile; HMMIO m_hmmioDemoFile; MMCKINFO m_ckRIFF, m_ckfmt, m_ckdata; int m_nDataLeft; WAVEFORMATEX *m_pwfx; PCMWAVEFORMAT m_pcmWaveFormat; int m_cbExtraAlloc; MMIOINFO m_mmioInfo; // BD 9/13/05 /*int DEMO; int rndcnt; int bufcnt;*/ // Created here so not created each time Read or Write Data is called // Otherwise these could be local variables - trade speed for size int m_nCopyLength, m_nActualWrite; int m_i; // Error variables int m_nError; char m_szError[ERROR_LENGTH]; public: //WAVEHDR lpDemoData; //DWORD dwDemoDataSize; // Constructor (empty) / Destructor CWavWrite(); virtual ~CWavWrite(); // Data processing - too large to be effective as an inline functions // BD added lat param for demo buffer //int Write(BYTE *pBuffer, int nDataSize, WAVEHDR *pDemoBuffer); int Write(BYTE *pBuffer, int nDataSize); void WriteDemo(BYTE *pBuffer, int nDataSize); // File Manipulation void Open(void); void Init(MMCKINFO *pckRIFF, MMCKINFO *pckfmt, MMCKINFO *pckdata, WAVEFORMATEX *pwfx, int nBufferSize); void Init(short wBitsPerSample, int nSampleFrequency, short wChannels, int nBufferSize); void Close(void); // Parameter Manipulation void SetName(char *); char *GetName(void); // Parameters below may be different than input file, CWavRead. long GetNumberOfSamples(void); long GetSampleFrequency(void); short GetBitsPerSample(void); short GetNumberOfCha

[Achim Klein]

Many lines. I need a moment...

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We can do no great things, only small things with great love. - Mother Theresa

[Achim Klein]

I guess you have a class named CWavRead. I guess you want to pass the buffer that this class fills to other functions. I guess all of this takes place somewhere inside your CSingleDlg class. Please correct me, if I'm wrong. In this case my header file would approximately look like this:

// forward declaration
class CWavRead;

// class definition
class CSingleDlg
{
public:

...

private:

// my dialog 'knows' an object of the CWavRead class
CWavRead* m_wavReader;
};

And my implementation file would approximately look like this:

#include "SingleDlg.h"
#include "WavRead.h"

// constructor
CSingleDlg::CSingleDlg()
{
m_wavReader = new CWavRead;
}

// destructor
CSingleDlg::~CSingleDlg()
{
delete m_wavReader;
}

// read wav file
CSingleDlg::OnFileOpen()
{
m_wavReader->read(path);
}

// modify wav data
CSingleDlg::OnEditModify()
{
// get data
long size = m_wavReader->getBufferSize();
BYTE* buffer = m_wavReader->getBuffer();

// create local (temporary) object
CWavOperator operator;

// pass the read data
operator.DoSomething(buffer, size);
}

Is it useful ?

---

We can do no great things, only small things with great love. - Mother Theresa

[Achim Klein]

Unfortunately I don't know the interface of your CWavRead class...

---

We can do no great things, only small things with great love. - Mother Theresa

[billiam904]

Thanks. Can you give me an idea of the implementation code for the getBuffer function to make sure I'm doing it right. I wrote one but it kepts resetting. Here's my read .h #include #include #include #define ERROR_LENGTH 1024 class CReadDemoWave { public: BYTE m_pbyDemoBuffer; static int testinteger; void ReadDemoWave(); BYTE *ReadDemoIntoBuffer(); void PlayWav(); long QueueWaveData(HWAVEOUT HWaveOut, WAVEHDR * waveHeader, DWORD WaveDataPlayed, DWORD WaveBufSize, HMMIO HMmio); BYTE *GetDemoBuffer(void); //void WriteDemo(HMMIO recordHandle); //public: // =========== D == E == M == O ======================= // BD create demo buffer. WAVEHDR lpDemoData; DWORD dwDemoDataSize; int m_nDemoBufferSize; //BYTE* m_pbyDemoBuffer; HMMIO m_hmmio; //HMMIO hmmio; char m_szError[ERROR_LENGTH]; int m_nError; MMIOINFO m_mmioInfo; DWORD dwDataSize; DWORD dwCount; HPSTR m_hptr; int m_nBufferSize; //WAVEFORMATEX waveFormat; }; Bill Dennis Orlando, FL

[Achim Klein]

If your read function fills m_pbyDemoBuffer, just write

BYTE* CReadDemoWave::getBuffer() const
{
return m_pbyDemoBuffer;
}

Returning a reference (pointer) breaks the privacy concept of your class, but it's handy.

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We can do no great things, only small things with great love. - Mother Theresa

[billiam904]

I have it like this: BYTE *CReadDemoWave::GetDemoBuffer(void) { return &m_pbyDemoBuffer; } When I take out the refrence (&), I get a compiler error saying it can't convert from BYTE to BYTE*. It's been 15 years since I've worked with pointers so not sure I am doing this correctly. My pointer seems to be resetting itself from the time the buffer is created and the time I call GetDemoBuffer(). Bill Dennis Orlando, FL

[Achim Klein]

BYTE m_pbyDemoBuffer is no array. It's just one number. If you want to create an array, please use new and delete:

int size = 1000;

// allocate memory
BYTE* array = new BYTE[size];

// free memory
delete[] array;

It's like malloc and free.

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We can do no great things, only small things with great love. - Mother Theresa

[billiam904]

In another post, I asked someone to show me how to allocate member for m_pbyDemoBuffer. I am rewading the wave data into a LPSTR variable, then creating and allocating memory for m_pbyDemoBuffer using GlobalAlloc and doing memcpy from lpDemoData.lpData to m_pbyDemoBuffer. I am then returning *m_pbyDemoBuffer in GetDemoBuffer(). So, not using arrays here. Bill Dennis Orlando, FL

[Achim Klein]

I am reading the wave data into a LPSTR variable, [...] How do you allocate the memory at the position your LPSTR variable points to ?

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We can do no great things, only small things with great love. - Mother Theresa

[billiam904]

I've pasted part of the code below. I have a lot of junk commented out in the actual .cpp file but if you want that, I can send it without violating my contract. Thanks. ''Allocate space for data in lpDemoData structure. // lpData is LPSTR. if (!( lpDemoData.lpData = (char *)VirtualAlloc(0, dwDemoDataSize<<1, MEM_COMMIT, PAGE_READWRITE))) { printf("ERROR: Can't allocate memory for WAVE buffer!\n"); } // Read Data Chunk into lpData if (readres = mmioRead(hmmio, (HPSTR )lpDemoData.lpData, dwDemoDataSize) != dwDemoDataSize) { AfxMessageBox("Error: Failed to read data chunk."); mmioClose(hmmio,0); return; } //Create byte-based buffer, allocate memory and copy // lpData to it. int lenlpData=strlen(lpDemoData.lpData); m_pbyDemoBuffer=(BYTE)GlobalAlloc(GMEM_MOVEABLE | GMEM_SHARE, lenlpData ); memcpy((BYTE*)m_pbyDemoBuffer, lpDemoData.lpData, lenlpData); Bill Dennis Orlando, FL

[Achim Klein]

Yeah, if your project isn't yet working, I'll have a look at it.

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We can do no great things, only small things with great love. - Mother Theresa