这段C语言代码转换成PHP代码

```c
//检验数据
static int NZ_CheckFrameData(const unsigned char *pBuf,int nLen)
{
    PCDZDATAFRAME pCDZDF = (PCDZDATAFRAME)pBuf;
    int nRet=0;
    unsigned int nCSLen, nChkSum = 0, i;
    unsigned char *pChkDat = (unsigned char *)pBuf;//校验和域: :采用累计和计算校验值，并取校验和的低 8 位，计算范围包含从命令代码和 数据域

    if (!pBuf)
    {
        return 0;
    }

    nCSLen = pCDZDF->fLen + 2 - 4;
    for (i = 0; i < nCSLen; i++)
    {
        nChkSum += pChkDat[i];
    }

    if(!memcmp(&pBuf[nLen-4], &nChkSum, sizeof(nChkSum)))
    {
        nRet=1;
    }
    
    return nRet;
}

```