1# UsbDeviceMemMap 2<!--Kit: Driver Development Kit--> 3<!--Subsystem: Driver--> 4<!--Owner: @lixinsheng2--> 5<!--Designer: @w00373942--> 6<!--Tester: @dong-dongzhen--> 7<!--Adviser: @w_Machine_cc--> 8 9## Overview 10 11Device memory map created by calling <b>OH_Usb_CreateDeviceMemMap</b>. A buffer using the device memory map can provide better performance. 12 13**Since**: 10 14 15**Related module**: [UsbDDK](capi-usbddk.md) 16 17**Header file:** [usb_ddk_types.h](capi-usb-ddk-types-h.md) 18 19## Summary 20 21### Member Variables 22 23| Name| Description| 24| -- | -- | 25| uint8_t* const address | Buffer address.| 26| const size_t size | Pointer to the buffer size.| 27| uint32_t offset | Offset of the used buffer. The default value is **0**, indicating that there is no offset and the buffer starts from the specified {@link address}.| 28| uint32_t bufferLength | Length of the used buffer. By default, the value is equal to the {@link size}, indicating that the entire buffer is used.| 29| uint32_t transferedLength | Length of the transferred data.| 30