Description
These are the data types available in the OpenCL C programming language. Click on a category name in the table below to see information about specific data types.
| Data type category | Included data types |
|---|---|
| Scalar data types | bool, char, cl_char, unsigned char, uchar, cl_uchar, short, cl_short, unsigned short, ushort, cl_ushort, int, cl_int, unsigned int, uint, cl_uint, long, cl_long, unsigned long, ulong, cl_ulong, float, size_t, ptrdiff_t, intptr_t, uintptr_t, void, double, and half floating point types. |
| Vector data types |
charn, ucharn,
shortn, ushortn,
intn, uintn,
longn, ulongn,
floatn, doublen,
and optional halfn types.
|
| Abstract data types | cl_platform_id, cl_device_id, cl_context, cl_command_queue, cl_mem, cl_program, cl_kernel, cl_event, and cl_sampler. |
| Reserved Data Types |
booln,
halfn, quad,
quadn,
complex half, complex halfn,
imaginary half, imaginary halfn,
complex float, complex floatn,
imaginary float, imaginary floatn,
complex double, complex doublen,
imaginary double, imaginary doublen,
complex quad, complex quadn,
imaginary quad, imaginary quadn,
floatnxm,
doublenxm,
long double, long doublen,
long long, long longn,
unsigned long long, ulong long, and
ulong longn.
|
| Other data types | image2d_t, image3d_t, image2d_array_t, image1d_t, image1d_buffer_t, image1d_array_t, image2d_depth_t, image2d_array_depth_t, sampler_t, queue_t, ndrange_t, clk_event_t, reserve_id_t, event_t, cl_mem_fence_flags, image2d_array_msaa_t_t, image2d_msaa_depth_t_t, and image2d_array_msaa_depth_t_t. |
Alignment of Types
A data item declared to be a data type in memory is always aligned to the size of the data type in bytes. For example, a float4 variable will be aligned to a 16-byte boundary, and a char2 variable will be aligned to a 2-byte boundary.
For 3-component vector data types, the size of the data type is 4 *
sizeof(component). This means that a 3-component vector data type
will be aligned to a 4 * sizeof(component) boundary. The
vload3 and
vstore3
built-in functions can be used to read and write, respectively, 3-component vector
data types from an array of packed scalar data type.
A built-in data type that is not a power of two bytes in size must be aligned to the next
larger power of two. This rule applies to built-in types only, not structs
or unions.
The OpenCL compiler is responsible for aligning data items to the appropriate alignment as required by the data type. For arguments to a __kernel function declared to be a pointer to a data type, the OpenCL compiler can assume that the pointee is always appropriately aligned as required by the data type. The behavior of an unaligned load or store is undefined, except for the vloadn, vload_halfn, vstoren, and vstore_halfn functions. The vector load functions can read a vector from an address aligned to the element type of the vector. The vector store functions can write a vector to an address aligned to the element type of the vector.
Alignment of Application Data Types
The user is responsible for ensuring that data passed into and out of OpenCL buffers are
natively aligned relative to the start of the buffer as described above. This implies
that OpenCL buffers created with CL_MEM_USE_HOST_PTR need to provide
an appropriately aligned host memory pointer that is aligned to the data types used to
access these buffers in a kernel(s). As well, the user is responsible to ensure that
data passed into and out of OpenCL images are properly aligned to the granularity of
the data representing a single pixel (e.g. image_num_channels
* sizeof(image_channel_data_type)) except for
CL_RGB and CL_RGBx images where
the data must be aligned to the granularity of a single channel in a pixel
(i.e. sizeof(image_channel_data_type)).
OpenCL makes no requirement about the alignment of OpenCL application defined data
types outside of buffers and images, except that the underlying vector primitives (e.g.
__cl_float4) where defined shall be directly accessible as such
using appropriate named fields in the cl_type union. Nevertheless,
it is recommended that the cl_platform.h header should attempt to
naturally align OpenCL defined application data types (e.g. cl_float4)
according to their type.
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