获取USB_BANDWIDTH_INFO结构的问题

Question

我正在用C++编写一个Windows应用程序，从外部USB摄像头读取图像并显示它们(这很好)。我喜欢同时监控使用的USB带宽。我知道存在一个USB_BANDWIDTH_INFO结构(信息)，但我不知道如何使用它。更确切地说:结构本身非常清楚，但是我如何获得/读取它(没有找到任何解释这一点的示例代码)？

Answer 1

根据MSDN

IOCTL_USB_USER_REQUEST I/O控制请求使用USB_BANDWIDTH_INFO结构来检索有关分配带宽的信息。

因此，您需要使用DeviceIoControl调用IOCTL_USB_USER_REQUEST。

参考官方例子，您可以找到：

GetHostControllerInfo(
    HANDLE hHCDev, 
    PUSBHOSTCONTROLLERINFO hcInfo)
{
    USBUSER_CONTROLLER_INFO_0 UsbControllerInfo;
    DWORD                      dwError = 0;
    DWORD                      dwBytes = 0;
    BOOL                       bSuccess = FALSE;

    memset(&UsbControllerInfo, 0, sizeof(UsbControllerInfo));

    // set the header and request sizes
    UsbControllerInfo.Header.UsbUserRequest = USBUSER_GET_CONTROLLER_INFO_0;
    UsbControllerInfo.Header.RequestBufferLength = sizeof(UsbControllerInfo);

    //
    // Query for the USB_CONTROLLER_INFO_0 structure
    //
    bSuccess = DeviceIoControl(hHCDev,
            IOCTL_USB_USER_REQUEST,
            &UsbControllerInfo,
            sizeof(UsbControllerInfo),
            &UsbControllerInfo,
            sizeof(UsbControllerInfo),
            &dwBytes,
            NULL);

    if (!bSuccess)
    {
        dwError = GetLastError();
        OOPS();
    }
    else
    {
        hcInfo->ControllerInfo = (PUSB_CONTROLLER_INFO_0) ALLOC(sizeof(USB_CONTROLLER_INFO_0));
        if(NULL == hcInfo->ControllerInfo)
        {
            dwError = GetLastError();
            OOPS();
        }
        else
        {
            // copy the data into our USB Host Controller's info structure
            memcpy(hcInfo->ControllerInfo, &UsbControllerInfo.Info0, sizeof(USB_CONTROLLER_INFO_0));
        }
    }
    return dwError;
}

您可以修改它，例如：

USBUSER_CONTROLLER_INFO_0 UsbControllerInfo;
UsbControllerInfo.Header.UsbUserRequest = USBUSER_GET_BANDWIDTH_INFORMATION;
UsbControllerInfo.Header.RequestBufferLength = sizeof(UsbControllerInfo);
USB_BANDWIDTH_INFO UsbBandInfo{};
DWORD                      dwError = 0;
DWORD                      dwBytes = 0;
BOOL                       bSuccess = FALSE;
    
bSuccess = DeviceIoControl(hHCDev,
    IOCTL_USB_USER_REQUEST,
    &UsbControllerInfo,
    sizeof(UsbControllerInfo),
    &UsbBandInfo,
    sizeof(USB_BANDWIDTH_INFO),
    &dwBytes,
    NULL);