Question

我使用MapVirtualFile使用C ++ VS2010在Window下映射文件。空白是

  void*                   m_pVoiceData;

我现在想用数据填充结构的向量。

结构是

struct udtPitchmark
{
    unsigned long ByteStart;
    unsigned long ByteCount;
    unsigned long F0;
};

struct udtPitchmarks
{
    vector<udtPitchmark>Pitchmarks;
};

我一直在使用

void clsMapping::FeedPitchmarksFromMap(udtPitchmarks &uAudioInfo,unsigned long int uBytePos)
{

    unsigned int iCountPM;
    memcpy(&iCountPM, &((char*)(m_pVoiceData))[uBytePos],sizeof(unsigned long));

    uAudioInfo.Pitchmarks.resize(iCountPM);

    for (unsigned int i=0;i<iCountPM;i++)
    {
        iBytePos+=sizeof(unsigned long);
        unsigned long int iByteStart;
        memcpy(&iByteStart, &((char*)(m_pVoiceData))[iBytePos],4);

        iBytePos+=sizeof(unsigned long);
        unsigned long int iByteCount;
        memcpy(&iByteCount, &((char*)(m_pVoiceData))[iBytePos],4);

        iBytePos+=sizeof(unsigned long);
        unsigned int iF0;
        memcpy(&iF0, &((char*)(m_pVoiceData))[iBytePos],4);

        uAudioInfo.Pitchmarks[i].ByteStart =iByteStart;
        uAudioInfo.Pitchmarks[i].ByteCount =iByteCount;
        uAudioInfo.Pitchmarks[i].F0 =iF0;
    }
}

每个音标都有3个memcpy。但我希望我能一次阅读所有的音标。但是我不知道该怎么做。

存储的结构如下：

vector<udtPitchmarks>::iterator it = nPitchmarks.Content().begin();
for (;it != nPitchmarks.Content().end(); ++it)
{
    unsigned int iCountPMs = it->Pitchmarks.size();
    fwrite(&iCountPMs,sizeof(unsigned int),1,outfile);

    vector<udtPitchmark>::iterator it2 = it->Pitchmarks.begin();
    for(;it2 != it->Pitchmarks.end(); ++it2)
    {
        fwrite(&it2->ByteStart,sizeof(unsigned long),1,outfile);
        fwrite(&it2->ByteCount,sizeof(unsigned long),1,outfile);
        fwrite(&it2->F0,sizeof(unsigned long),1,outfile);
    }
}

有人可以帮忙吗？

Answer 1

你可以一次阅读整个udtPitchmark结构

m_pVoiceData = (char *)m_pVoiceData + sizeof(unsigned int); // size field

memcpy( &uAudioInfo.Pitchmarks[i], (udtPitchmark *)m_pVoiceData + i, sizeof udtPitchmark );

或整个载体：

memcpy( &uAudioInfo.Pitchmarks[0], (udtPitchmark *)m_pVoiceData, sizeof(udtPitchmark ) * iCountPM);

Answer 2

如果您将数据作为数组放置，您可以一次性写入数据。访问器功能可以帮助您维护可读的界面：

struct Pitchmark
{
    unsigned long data[3];

    unsigned long & start() { return data[0]; }
    unsigned long & count() { return data[1]; }
    unsigned long & f0()    { return data[2]; }

    unsigned char * ptr() { return static_cast<unsigned char *>(data); }
};

Pitchmark pm;
memcpy(pm.ptr(), m_pVoiceData, sizeof pm.data);

在结构传染媒介的MemCpy

2 个答案: