Method GetVirtualMemAuto

gcore/rawdataset.cpp:1515–1560

/************************************************************************/

CPLVirtualMem *RawRasterBand::GetVirtualMemAuto(GDALRWFlag eRWFlag,
                                                int *pnPixelSpace,
                                                GIntBig *pnLineSpace,
                                                CSLConstList papszOptions)
{
    CPLAssert(pnPixelSpace);
    CPLAssert(pnLineSpace);

    const vsi_l_offset nSize =
        static_cast<vsi_l_offset>(nRasterYSize - 1) * nLineOffset +
        static_cast<vsi_l_offset>(nRasterXSize - 1) * nPixelOffset +
        GDALGetDataTypeSizeBytes(eDataType);

    const char *pszImpl = CSLFetchNameValueDef(
        papszOptions, "USE_DEFAULT_IMPLEMENTATION", "AUTO");
    if (VSIFGetNativeFileDescriptorL(fpRawL) == nullptr ||
        !CPLIsVirtualMemFileMapAvailable() || NeedsByteOrderChange() ||
        static_cast<size_t>(nSize) != nSize || nPixelOffset < 0 ||
        nLineOffset < 0 || EQUAL(pszImpl, "YES") || EQUAL(pszImpl, "ON") ||
        EQUAL(pszImpl, "1") || EQUAL(pszImpl, "TRUE"))
    {
        return GDALRasterBand::GetVirtualMemAuto(eRWFlag, pnPixelSpace,
                                                 pnLineSpace, papszOptions);
    }

    FlushCache(false);

    CPLVirtualMem *pVMem = CPLVirtualMemFileMapNew(
        fpRawL, nImgOffset, nSize,
        (eRWFlag == GF_Write) ? VIRTUALMEM_READWRITE : VIRTUALMEM_READONLY,
        nullptr, nullptr);
    if (pVMem == nullptr)
    {
        if (EQUAL(pszImpl, "NO") || EQUAL(pszImpl, "OFF") ||
            EQUAL(pszImpl, "0") || EQUAL(pszImpl, "FALSE"))
        {
            return nullptr;
        }
        return GDALRasterBand::GetVirtualMemAuto(eRWFlag, pnPixelSpace,
                                                 pnLineSpace, papszOptions);
    }

    *pnPixelSpace = nPixelOffset;
    *pnLineSpace = nLineOffset;
    return pVMem;
}

/************************************************************************/
/* ==================================================================== */