Scalar Data Types

Built-in scalar data types.

Description

These are the data types available in the OpenCL C programming language used to create kernels that are executed on OpenCL device(s). The OpenCL C programming language (also referred to as OpenCL C) is based on the ISO/IEC 9899:1999 C language specification (a.k.a. C99 specification) with specific extensions and restrictions. Please refer to the ISO/IEC 9899:1999 specification for a detailed description of the language grammar. This section describes modifications and restrictions to ISO/IEC 9899:1999 supported in OpenCL C.

Most built-in scalar data types are also declared as appropriate types in the OpenCL API (and header files) that can be used by an application. The following table describes the built-in scalar data type in the OpenCL C programming language and the corresponding data type available to the application:

Type in OpenCL Language Description API type for application
bool A conditional data type which is either true or false. The value true expands to the integer constant 1 and the value false expands to the integer constant 0. When any scalar value is converted to bool, the result is 0 if the value compares equal to 0; otherwise, the result is 1. n/a
char A signed two's complement 8-bit integer. cl_char

unsigned char,
uchar

An unsigned 8-bit integer. cl_uchar
short A signed two's complement 16-bit integer. cl_short

unsigned short,
ushort

An unsigned 16-bit integer. cl_ushort
int A signed two's complement 32-bit integer. cl_int

unsigned int,
uint

An unsigned 32-bit integer. cl_uint
long A signed two's complement 64-bit integer. cl_long

unsigned long,
ulong

An unsigned 64-bit integer. cl_ulong
float A single precision float. The float data type must conform to the IEEE 754 single precision storage format. cl_float
half A 16-bit float. The half data type must conform to the IEEE 754-2008 half precision storage format. cl_half
size_t The unsigned integer type of the result of the sizeof operator. This is a 32-bit unsigned integer if CL_DEVICE_ADDRESS_BITS defined in clGetDeviceInfo is 32-bits and is a 64-bit unsigned integer if CL_DEVICE_ADDRESS_BITS is 64-bits. n/a
ptrdiff_t A signed integer type that is the result of subtracting two pointers. This is a 32-bit signed integer if CL_DEVICE_ADDRESS_BITS defined in clGetDeviceInfo is 32-bits and is a 64-bit signed integer if CL_DEVICE_ADDRESS_BITS is 64-bits. n/a
intptr_t A signed integer type with the property that any valid pointer to void can be converted to this type, then converted back to pointer to void, and the result will compare equal to the original pointer. n/a
uintptr_t An unsigned integer type with the property that any valid pointer to void can be converted to this type, then converted back to pointer to void, and the result will compare equal to the original pointer. n/a
void The void type comprises an empty set of values; it is an incomplete type that cannot be completed. void

Optional Double Precision and Half Floating Point

OpenCL 1.0 adds support for double precision and half floating-point as optional extensions. The double data type must confirm to the IEEE-754 double precision storage format.

An application that wants to use double will need to include the #pragma OPENCL EXTENSION cl_khr_fp64 : enable directive before any double precision data type is declared in the kernel code. This will extended the list of built-in vector and scalar data types to include the following:

Type in OpenCL Language Description API type for application
double A double precision float. cl_double
double2 A 2-component double vector. cl_double2
double3 A 3-component double vector. cl_double3
double4 A 4-component double vector. cl_double4
double8 An 8-component double vector. cl_double8
double16 A 16-component double vector. cl_double16

An application that wants to use half and halfn will need to include the #pragma OPENCL EXTENSION cl_khr_fp16 : enable directive. This will extended the list of built-in vector and scalar data types to include the following:

Type in OpenCL Language Description API type for application
half2 A 2-component half-precision floating-point vector. cl_half2
half3 A 3-component half-precision floating-point vector. cl_half3
half4 A 4-component half-precision floating-point vector. cl_half4
half8 An 8-component half-precision floating-point vector. cl_half8
half16 A 16-component half-precision floating-point vector. cl_half16

Specification

OpenCL Specification

Also see

Macros and Limits, Vector Data Types, Reserved Data Types, Other Data Types, Abstract Data Types, cl_khr_fp16, cl_khr_fp64

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