clCreateSubBuffer
clCreateSubBuffer
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3
clCreateSubBuffer Creates a new buffer object (referred to as a sub-buffer object) from an existing buffer object.

##

cl_mem `clCreateSubBuffer` cl_mem buffer cl_mem_flags flags cl_buffer_create_type buffer_create_type const void*buffer_create_info cl_int*errcode_ret

## Parameters

`buffer`

  A valid object and cannot be a sub-buffer object.

`flags`

  A bit-field that is used to specify allocation and usage information about the sub-buffer memory object being created and is described in the table below. If the `CL_MEM_READ_WRITE`, `CL_MEM_READ_ONLY` or `CL_MEM_WRITE_ONLY` values are not specified in `flags`, they are inherited from the corresponding memory access qualifers associated with `buffer`. The `CL_MEM_USE_HOST_PTR`, `CL_MEM_ALLOC_HOST_PTR` and `CL_MEM_COPY_HOST_PTR` values cannot be specified in `flags` but are inherited from the corresponding memory access qualifiers associated with `buffer`. If `CL_MEM_COPY_HOST_PTR` is specified in the memory access qualifier values associated with `buffer` it does not imply any additional copies when the sub-buffer is created from `buffer`. If the `CL_MEM_HOST_WRITE_ONLY`, `CL_MEM_HOST_READ_ONLY` or `CL_MEM_HOST_NO_ACCESS` values are not specified in `flags`, they are inherited from the corresponding memory access qualifiers associated with `buffer`.

  &clCreate_memflagsInc;
`buffer_create_type` and `buffer_create_info`

  Describes the type of buffer object to be created. The list of supported values for `buffer_create_type` and corresponding descriptor that `buffer_create_info` points to is described below.

  cl_buffer_create_type | Description
  --- | ---
  CL_BUFFER_CREATE_TYPE_REGION | Create a buffer object that represents a specific region in `buffer`. `buffer_create_info` is a pointer to the following structure:
      typedef struct _cl_buffer_region {
          size_t origin;
          size_t size;
      } cl_buffer_region;
  (`origin, size`) defines the offset and size in bytes in `buffer`. If `buffer` is created with `CL_MEM_USE_HOST_PTR`, the `host_ptr` associated with the buffer object returned is `host_ptr` + `origin`. The buffer object returned references the data store allocated for `buffer` and points to a specific region given by (`origin, size`) in this data store. `CL_INVALID_VALUE` is returned in `errcode_ret` if the region specified by (`origin, size`) is out of bounds in `buffer`. `CL_INVALID_BUFFER_SIZE` if `size` is 0. `CL_MISALIGNED_SUB_BUFFER_OFFSET` is returned in `errcode_ret` if there are no devices in context associated with `buffer` for which the `origin` value is aligned to the `CL_DEVICE_MEM_BASE_ADDR_ALIGN` value.

## Notes

Concurrent reading from, writing to and copying between both a buffer object and its sub-buffer object(s) is undefined. Concurrent reading from, writing to and copying between overlapping sub-buffer objects created with the same buffer object is undefined. Only reading from both a buffer object and its sub-buffer objects or reading from multiple overlapping sub-buffer objects is defined.

## Errors

Returns a valid non-zero buffer object and `errcode_ret` is set to CL_SUCCESS if the buffer object is created successfully. Otherwise, it returns one of the following error in `errcode_ret`:

- CL_INVALID_MEM_OBJECT if `buffer` is not a valid buffer object or is a sub-buffer object.
- CL_INVALID_VALUE if `buffer` was created with `CL_MEM_WRITE_ONLY` and `flags` specifies `CL_MEM_READ_WRITE` or `CL_MEM_READ_ONLY`, or if `buffer` was created with `CL_MEM_READ_ONLY` and `flags` specifies `CL_MEM_READ_WRITE` or `CL_MEM_WRITE_ONLY`, or if `flags` specifies `CL_MEM_USE_HOST_PTR` or `CL_MEM_ALLOC_HOST_PTR` or `CL_MEM_COPY_HOST_PTR`.
- CL_INVALID_VALUE if `buffer` was created with `CL_MEM_HOST_WRITE_ONLY` and `flags` specifies `CL_MEM_HOST_READ_ONLY` or if `buffer` was created with `CL_MEM_HOST_READ_ONLY` and `flags` specifies `CL_MEM_HOST_WRITE_ONLY`, or if `buffer` was created with `CL_MEM_HOST_NO_ACCESS` and `flags` specifies `CL_MEM_HOST_READ_ONLY` or `CL_MEM_HOST_WRITE_ONLY`.
- CL_INVALID_VALUE if value specified in `buffer_create_type` is not valid.
- CL_INVALID_VALUE if value(s) specified in `buffer_create_info` (for a given `buffer_create_type`) is not valid or if `buffer_create_info` is NULL.
- CL_INVALID_BUFFER_SIZE if size is 0.
- CL_MEM_OBJECT_ALLOCATION_FAILURE if there is a failure to allocate memory for sub-buffer object.
- CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL implementation on the device.
- CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

## Specification

OpenCL Specification

## Also see

clCreateBuffer, clEnqueueReadBuffer, clEnqueueWriteBuffer, clEnqueueCopyBuffer

##