Provided by: opencl-1.2-man-doc_1.0~svn33624-1_all 
NAME
Data_Types - OpenCL data types.
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 │
├────────────────────────┼──────────────────────────────────┤
│scalarDataTypes(3clc) │ bool, char, cl_char, unsigned │
│ │ char, uchar, cl_uchar, short, │
│ │ cl_short, unsigned short, │
│ │ ushort, int, unsigned int, uint, │
│ │ long, unsigned long, ulong, │
│ │ float, half, size_t, ptrdiff_t, │
│ │ intptr_t, uintptr_t, void, │
│ │ double, and half floating point │
│ │ types. │
├────────────────────────┼──────────────────────────────────┤
│vectorDataTypes(3clc) │ charn, ucharn, shortn, ushortn, │
│ │ intn, uintn, longn, ulongn, │
│ │ floatn, doublen, and optional │
│ │ halfn types. │
├────────────────────────┼──────────────────────────────────┤
│abstractDataTypes(3clc) │ cl_platform_id, cl_device_id, │
│ │ cl_context, cl_command_queue, │
│ │ cl_mem, cl_program, cl_kernel, │
│ │ cl_event, and cl_sampler. │
├────────────────────────┼──────────────────────────────────┤
│reservedDataTypes(3clc) │ 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. │
├────────────────────────┼──────────────────────────────────┤
│otherDataTypes(3clc) │ image2d_t, image3d_t, │
│ │ image2d_array_t, image1d_t, │
│ │ image31_buffer_t, │
│ │ image1d_array_t, sampler_t, and │
│ │ event_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 vloadn(3clc) and vstoren(3clc) 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 functionQualifiers(3clc) 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(3clc), vload_halfn(3clc), vstoren(3clc), and
vstore_halfn(3clc) 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.
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.
SPECIFICATION
OpenCL Specification[1]
AUTHORS
The Khronos Group
COPYRIGHT
Copyright © 2007-2010 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and/or associated documentation files (the "Materials"), to deal in the Materials
without restriction, including without limitation the rights to use, copy, modify, merge,
publish, distribute, sublicense, and/or sell copies of the Materials, and to permit
persons to whom the Materials are furnished to do so, subject to the condition that this
copyright notice and permission notice shall be included in all copies or substantial
portions of the Materials.
NOTES
1. OpenCL Specification
page 195, section 6.1.1 - Built-in Scalar Data Types