USBD_CalculateUsbBandwidth function (usbdlib.h)
The USBD_CalculateUsbBandwidth routine has been deprecated in Windows XP and later operating systems. Do not use.
Syntax
ULONG USBD_CalculateUsbBandwidth(
[in] ULONG MaxPacketSize,
[in] UCHAR EndpointType,
[in] BOOLEAN LowSpeed
);
Parameters
[in] MaxPacketSize
Specifies the maximum packet size.
[in] EndpointType
Contains a value of type USBD_PIPE_TYPE that specifies the pipe type.
[in] LowSpeed
Indicates, when TRUE, that the device is a low speed device. When FALSE, this member indicates that the device is a hi-speed device.
Return value
The USBD_CalculateUsbBandwidth routine returns zero for bulk and control endpoints and the bandwidth consumed in bits per millisecond. returns for all other endpoints.
Remarks
The USBD_CalculateUsbBandwidth routine approximates the bandwidth using the following procedure. First, USBD_CalculateUsbBandwidth adds the largest possible packet size, specified in MaxPacketSize, to the overhead associated with the type of end point specified in EndpointType. Next, USBD_CalculateUsbBandwidth multiplies this sum by 8 to convert the units from bytes per millisecond into bits per millisecond. Finally, USBD_CalculateUsbBandwidth multiplies this quantity by 7/6 to account for filler bits. In a worst case scenario, there will be one bit of filler data stuffed into the data stream for every six bits of data. USBD_CalculateUsbBandwidth uses worst-case assumptions to calculate the bandwidth required by the pipe.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Deprecated. |
| Target Platform | Universal |
| Header | usbdlib.h (include Usbdlib.h) |
| Library | Usbd.lib |
| IRQL | <=DISPATCH_LEVEL |