signbit

Test for sign bit.

int signbit ( float )
int n signbit ( floatn )

int signbit (double) // if double extension enabled longn signbit (doublen) // if double extension enabled
int signbit (half) // if half extension enabled shortn signbit (halfn) // if half extension enabled

Description

The built-in function signbit tests for sign bit. The scalar version of the function returns a 1 if the sign bit in the float is set else returns 0. The vector version of the function returns the following for each component in floatn: a -1 if the sign bit in the float is set else returns 0.

If extended with cl_khr_fp64 or cl_khr_fp16 to enable double or half respectively, then signbit returns -1 if the sign bit in the float is set; otherwise returns 0.

Notes

This function returns a 0 if the specified relation is false and a 1 if the specified relation is true for scalar argument types. It returns a 0 if the specified relation is false and a -1 (i.e. all bits set) if the specified relation is true for vector argument types.

The built-in relational functions can be used with built-in scalar or vector types as arguments and return a scalar vector integer result. The argment type gentype can be char, charn, uchar, ucharn, short, shortn, ushort, ushortn, int, intn, uint, uintn, long, longn, ulong, ulongn, float, and floatn. The argument type igentype refers to signed integer vector types i.e. char, charn, short, shortn, int, intn, long, and longn. The argument type ugentype refers to unsigned integer vector types i.e. uchar, ucharn, ushort, ushortn, uint, uintn, ulong, and ulongn.

If extended with cl_khr_fp64, generic type name gentype may indicate double and double{2|4|8|16} as arguments and return values. If extended with cl_khr_fp16, generic type name gentype may indicate half and half{2|4|8|16} as arguments and return values.

Specification

OpenCL Specification

Also see

Relational Functions

Copyright © 2007-2009 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.