1# DDK_Ashmem 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 **OH_DDK_CreateAshmem**. A buffer using the device memory map can provide better performance. 12 13**Since**: 12 14 15**Related module**: [BaseDdk](capi-baseddk.md) 16 17**Header file:** [ddk_types.h](capi-ddk-types-h.md) 18 19## Summary 20 21### Member Variables 22 23| Name| Description| 24| -- | -- | 25| int32_t ashmemFd | File descriptor of the **Ashmem** object.| 26| const uint8_t* address | Buffer address.| 27| const uint32_t size | Buffer size.| 28| 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 address.| 29| uint32_t bufferLength | Length of the buffer. By default, the value is equal to that of **size**, indicating that the entire buffer is used.| 30| uint32_t transferredLength | Length of the data to be transferred.| 31