signbit

Test for sign bit.

int signbit ( float )
intn 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

The relational and equality operators (<, <=, >, >=, !=, ==) can be used with scalar and vector built-in types and produce a scalar or vector signed integer result respectively.

The built-in relational functions can be used with built-in scalar or vector types as arguments and return a scalar or vector integer result. If an implementation extends this specification to support IEEE-754 flags or exceptions, then all built-in Relational shall proceed without raising the invalid floating-point exception when one or more of the operands are NaNs.

The built-in relational functions are extended with cl_khr_fp64 to include appropriate versions of functions that take double, and double{2|3|4|8|16} as arguments and return values. They are also extended with cl_khr_fp16 to include appropriate versions of functions that take half, and half{2|3|4|8|16} as arguments and return values. The relational and equality operators (<, <=, >, >=, !=, ==) can be used with doublen vector types and shall produce a vector longn result.

The function returns a 0 if the specified relation is false and a 1 if the specified relation is true for scalar argument types. These functions shall return 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.

Specification

OpenCL Specification

Also see

Relational Functions

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