Base DDK
Overview
Provides APIs for creating, mapping, unmapping, and destroying an Ashmem object.
System capability: SystemCapability.Driver.DDK.Extension
Since
12
Summary
File
| Name | Description |
|---|---|
| ddk_api.h | Declares the HID DDK functions for accessing an input device from the host. File to include: <base/ddk_api.h> Library: libddk_base.z.so |
| ddk_types.h | Defines the enum variables and structs used in the HID DDK. File to include: <base/ddk_types.h> Library: libddk_base.z.so |
Structs
| Name | Description |
|---|---|
| DDK_Ashmem | Shared memory. |
Enums
| Name | Description |
|---|---|
| DDK_RetCode | Base DDK error code definitions. |
Functions
| Name | Description |
|---|---|
| OH_DDK_CreateAshmem (const uint8_t *name, DDK_Ashmem **ashmem) | Creates an Ashmem object. |
| OH_DDK_MapAshmem (DDK_Ashmem *ashmem, const uint8_t ashmemMapType) | Maps an Ashmem object. |
| OH_DDK_UnmapAshmem (DDK_Ashmem *ashmem) | Unmaps an Ashmem object. |
| OH_DDK_DestroyAshmem (DDK_Ashmem *ashmem) | Destroys an Ashmem object. |
Enum Description
DDK_RetCode
enum DDK_RetCode
Description
Base DDK error code definitions.
| Value | Description |
|---|---|
| DDK_SUCCESS | The operation is successful. |
| DDK_FAILED | Operation failed. |
| DDK_INVALID_PARAMETER | Invalid parameter. |
| DDK_INVALID_OPERATION | Invalid operation. |
| DDK_NULL_PTR | Null pointer. |
Function Description
OH_DDK_CreateAshmem()
DDK_RetCode OH_DDK_CreateAshmem(const uint8_t *name, uint32_t size, DDK_Ashmem **ashmem);
Description
Creates an Ashmem object.
Parameters
| Name | Description |
|---|---|
| name | Name of the Ashmem object. |
| size | Buffer size of the Ashmem object. |
| ashmem | Pointer to the Ashmem object. |
Returns
- DK_SUCCESS if the API is called successfully.
- DDK_INVALID_PARAMETER if the input name or ashmem is a null pointer, or size is 0.
- [DDK_FAILURE] (#ddk_retcode) if the attempt to create the shared memory or the DDK_Ashmem structure fails.
OH_DDK_MapAshmem()
DDK_RetCode OH_DDK_MapAshmem(DDK_Ashmem *ashmem, const uint8_t ashmemMapType);
Description
Maps an Ashmem object.
Parameters
| Name | Description |
|---|---|
| ashmem | Pointer to the Ashmem object. |
| ashmemMapType | Mapping type for the Ashmem object. |
Returns
- DK_SUCCESS if the API is called successfully.
- DDK_NULL_PTR if the input ashmem is a null pointer.
- [DDK_FAILURE] (#ddk_retcode) if the file descriptor of the shared memory is invalid.
- DDK_INVALID_OPERATION if calling the MapAshmem API fails.
OH_DDK_UnmapAshmem()
DDK_RetCode OH_DDK_UnmapAshmem(DDK_Ashmem *ashmem);
Description
Unmaps an Ashmem object.
Parameters
| Name | Description |
|---|---|
| ashmem | Pointer to the Ashmem object. |
Returns
- DK_SUCCESS if the API is called successfully.
- DDK_NULL_PTR if the input ashmem is a null pointer.
- [DDK_FAILURE] (#ddk_retcode) if the file descriptor of the shared memory is invalid.
OH_DDK_DestroyAshmem()
DDK_RetCode OH_DDK_DestroyAshmem(DDK_Ashmem *ashmem);
Description
Destroys the created shared memory.
Parameters
| Name | Description |
|---|---|
| ashmem | Pointer to the Ashmem object. |
Returns
- DK_SUCCESS if the API is called successfully.
- DDK_NULL_PTR if the input ashmem is a null pointer.
- [DDK_FAILURE] (#ddk_retcode) if the file descriptor of the shared memory is invalid.