NAME¶
cl_khr_fp16 - Optional half floating-point support.
#pragma OPENCL EXTENSION cl_khr_fp16 : enable |
DESCRIPTION¶
This extension adds support for half scalar and vector types as built-in types
that can be used for arithmetic operations, conversions, etc. An application
that wants to use
half and
halfn types will need
to include the directive shown above.
The list of built-in scalar and vector data types are extended to include the
types in the table below.
The built-in vector data types for
halfn 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 vector data types for
halfn as defined in the OpenCL C programming language and
the corresponding data type available to the application:
Type in OpenCL Language |
Description |
API type for application |
half2 |
2-component half-precision floating-point vector |
cl_half2 |
half3 |
3-component half-precision floating-point vector |
cl_half3 |
half4 |
4-component half-precision floating-point vector |
cl_half4 |
half8 |
8-component half-precision floating-point vector |
cl_half8 |
half16 |
16-component half-precision floating-point vector |
cl_half16 |
The relational, equality, logical and logical unary
operators(3clc) can
be used with
half scalar and
halfn vector types
and shall produce a scalar
int and vector
shortn
result respectively.
The OpenCL compiler accepts
an h
and H suffix on floating point
literals, indicating the literal is typed as a
half.
The macro names given in the following list must use the values specified. These
constant expressions are suitable for use in
#if preprocessing
directives.
The following table also describes the corresponding macro names available to
the application.
Macro in OpenCL Language |
value |
Macro for application |
#define HALF_DIG |
3 |
HALF_DIG |
#define HALF_MANT_DIG |
11 |
HALF_MANT_DIG |
#define HALF_MAX_10_EXP |
+4 |
HALF_MAX_10_EXP |
#define HALF_MAX_EXP |
+16 |
HALF_MAX_EXP |
#define HALF_MIN_10_EXP |
-4 |
HALF_MIN_10_EXP |
#define HALF_MIN_EXP |
-13 |
HALF_MIN_EXP |
#define HALF_RADIX |
2 |
HALF_RADIX |
#define HALF_MAX |
0x1.ffcp15h |
HALF_MAX |
#define HALF_MIN |
0x1.0p-14h |
HALF_MIN |
#define HALF_EPSILON |
0x1.0p-10h |
HALF_EPSILON |
The following constants are also available. They are of type
half and are
accurate within the precision of the
half type.
Constant |
Description |
M_E_H |
Value of e |
M_LOG2E_H |
Value of log2 e |
M_LOG10E_H |
Value of log10 e |
M_LN2_H |
Value of ln 2 |
M_LN10_H |
Value of ln 10 |
M_PI_H |
Value of π |
M_PI_2_H |
Value of π / 2 |
M_PI_4_H |
Value of π / 4 |
M_1_PI_H |
Value of 1 / π |
M_2_PI_H |
Value of 2 / π |
M_2_SQRTPI_H |
Value of 2 / √π |
M_SQRT2_H |
Value of √2 |
M_SQRT1_2_H |
Value of 1 / √2 |
Ann application may query the configuration information using the op-code
CL_DEVICE_HALF_FP_CONFIG with
clGetDeviceInfo(3clc) for an
OpenCL device that supports half precision floating-point.
SPECIFICATION¶
OpenCL Specification[1]
SEE ALSO¶
EXTENSION(3clc),
clGetDeviceInfo(3clc),
mathFunctions(3clc),
commonFunctions(3clc),
geometricFunctions(3clc),
relationalFunctions(3clc),
vectorDataLoadandStoreFunctions(3clc),
asyncCopyFunctions(3clc),
imageFunctions(3clc)
AUTHORS¶
The Khronos Group
COPYRIGHT¶
Copyright © 2007-2011 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 14, section 9.5 - Half Floating-Point