half  1.11
IEEE 754-based half-precision floating point library
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half Struct Reference

Half-precision floating point type. More...

Public Member Functions

Construction and assignment
constexpr half ()
 Default constructor.
 
 half (float rhs)
 Conversion constructor.
 
 operator float () const
 Conversion to single-precision.
 
halfoperator= (float rhs)
 Single-precision assignment.
 
Arithmetic updates
halfoperator+= (half rhs)
 Arithmetic assignment.
 
halfoperator-= (half rhs)
 Arithmetic assignment.
 
halfoperator*= (half rhs)
 Arithmetic assignment.
 
halfoperator/= (half rhs)
 Arithmetic assignment.
 
halfoperator+= (float rhs)
 Arithmetic assignment.
 
halfoperator-= (float rhs)
 Arithmetic assignment.
 
halfoperator*= (float rhs)
 Arithmetic assignment.
 
halfoperator/= (float rhs)
 Arithmetic assignment.
 
Increment and decrement
halfoperator++ ()
 Prefix increment.
 
halfoperator-- ()
 Prefix decrement.
 
half operator++ (int)
 Postfix increment.
 
half operator-- (int)
 Postfix decrement.
 

Detailed Description

Half-precision floating point type.

This class implements an IEEE-conformant half-precision floating point type with the usual arithmetic operators and conversions. It is implicitly convertible to single-precision floating point, which makes artihmetic expressions and functions with mixed-type operands to be of the most precise operand type. Additionally all arithmetic operations (and many mathematical functions) are carried out in single-precision internally. All conversions from single- to half-precision are done using truncation (round towards zero), but temporary results inside chained arithmetic expressions are kept in single-precision as long as possible (while of course still maintaining a strong half-precision type).

According to the C++98/03 definition, the half type is not a POD type. But according to C++11's less strict and extended definitions it is both a standard layout type and a trivially copyable type (even if not a POD type), which means it can be standard-conformantly copied using raw binary copies. But in this context some more words about the actual size of the type. Although the half is representing an IEEE 16-bit type, it does not neccessarily have to be of exactly 16-bits size. But on any reasonable implementation the actual binary representation of this type will most probably not ivolve any additional "magic" or padding beyond the simple binary representation of the underlying 16-bit IEEE number, even if not strictly guaranteed by the standard. But even then it only has an actual size of 16 bits if your C++ implementation supports an unsigned integer type of exactly 16 bits width. But this should be the case on nearly any reasonable platform.

So if your C++ implementation is not totally exotic or imposes special alignment requirements, it is a reasonable assumption that the data of a half is just comprised of the 2 bytes of the underlying IEEE representation.

Constructor & Destructor Documentation

constexpr half ( )

Default constructor.

This initializes the half to 0. Although this does not match the builtin types' default-initialization semantics and may be less efficient than no initialization, it is needed to provide proper value-initialization semantics.

half ( float  rhs)
explicit

Conversion constructor.

Parameters
rhsfloat to convert

Member Function Documentation

operator float ( ) const

Conversion to single-precision.

Returns
single precision value
half& operator= ( float  rhs)

Single-precision assignment.

Parameters
rhssingle-precision value to copy from
Returns
reference to this half
half& operator+= ( half  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Template Parameters
Etype of concrete half expression
Parameters
rhshalf to add
Returns
reference to this half
half& operator-= ( half  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Template Parameters
Etype of concrete half expression
Parameters
rhshalf to subtract
Returns
reference to this half
half& operator*= ( half  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Template Parameters
Etype of concrete half expression
Parameters
rhshalf to multiply with
Returns
reference to this half
half& operator/= ( half  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Template Parameters
Etype of concrete half expression
Parameters
rhshalf to divide by
Returns
reference to this half
half& operator+= ( float  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Parameters
rhssingle-precision value to add
Returns
reference to this half
half& operator-= ( float  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Parameters
rhssingle-precision value to subtract
Returns
reference to this half
half& operator*= ( float  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Parameters
rhssingle-precision value to multiply with
Returns
reference to this half
half& operator/= ( float  rhs)

Arithmetic assignment.

This operation uses the underlying single-precision implementation.

Parameters
rhssingle-precision value to divide by
Returns
reference to this half
half& operator++ ( )

Prefix increment.

This operation uses the underlying single-precision implementation.

Returns
incremented half value
half& operator-- ( )

Prefix decrement.

This operation uses the underlying single-precision implementation.

Returns
decremented half value
half operator++ ( int  )

Postfix increment.

This operation uses the underlying single-precision implementation.

Returns
non-incremented half value
half operator-- ( int  )

Postfix decrement.

This operation uses the underlying single-precision implementation.

Returns
non-decremented half value

The documentation for this struct was generated from the following file: