1# UsbDeviceMemMap
2
3
4## Overview
5
6Device memory map created by calling [OH_Usb_CreateDeviceMemMap()](_usb_ddk.md#oh_usb_createdevicememmap). A buffer using the device memory map can provide better performance.
7
8**Since**
9
1010
11
12**Related Modules**
13
14[USB DDK](_usb_ddk.md)
15
16
17## Summary
18
19
20### Member Variables
21
22| Name| Description|
23| -------- | -------- |
24| [address](#address) |  Buffer address.|
25| [size](#size) | Buffer size.|
26| [offset](#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.|
27| [bufferLength](#bufferlength) | Length of the used buffer. By default, the value is equal to the size, indicating that the entire buffer is used.|
28| [transferedLength](#transferedlength) | Length of the transferred data.|
29
30
31## Member Variable Description
32
33
34### address
35
36
37```
38uint8_t* const UsbDeviceMemMap::address
39```
40
41**Description**
42
43 Buffer address.
44
45
46### bufferLength
47
48
49```
50uint32_t UsbDeviceMemMap::bufferLength
51```
52
53**Description**
54
55Length of the used buffer. By default, the value is equal to the size, indicating that the entire buffer is used.
56
57
58### offset
59
60
61```
62uint32_t UsbDeviceMemMap::offset
63```
64
65**Description**
66
67Offset of the used buffer. The default value is 0, indicating that there is no offset and the buffer starts from the specified address.
68
69
70### size
71
72
73```
74const size_t UsbDeviceMemMap::size
75```
76
77**Description**
78
79Buffer size.
80
81
82### transferedLength
83
84
85```
86uint32_t UsbDeviceMemMap::transferedLength
87```
88
89**Description**
90
91Length of the transferred data.
92