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Diffstat (limited to 'doc/html/atomic/interface.html')
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1 files changed, 644 insertions, 16 deletions
diff --git a/doc/html/atomic/interface.html b/doc/html/atomic/interface.html index 1069f2ac0f..a7b95c9d77 100644 --- a/doc/html/atomic/interface.html +++ b/doc/html/atomic/interface.html @@ -132,6 +132,20 @@ <tr> <td> <p> + <code class="computeroutput"><span class="identifier">BOOST_ATOMIC_NO_FLOATING_POINT</span></code> + </p> + </td> +<td> + <p> + When defined, support for floating point operations is disabled. + Floating point types shall be treated similar to trivially copyable + structs and no capability macros will be defined. + </p> + </td> +</tr> +<tr> +<td> + <p> <code class="computeroutput"><span class="identifier">BOOST_ATOMIC_FORCE_FALLBACK</span></code> </p> </td> @@ -307,6 +321,102 @@ </tbody> </table></div> <p> + For compilers that support C++11 scoped enums, the library also defines scoped + synonyms that are preferred in modern programs: + </p> +<div class="informaltable"><table class="table"> +<colgroup> +<col> +<col> +</colgroup> +<thead><tr> +<th> + <p> + Pre-C++11 constant + </p> + </th> +<th> + <p> + C++11 equivalent + </p> + </th> +</tr></thead> +<tbody> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order_relaxed</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order</span><span class="special">::</span><span class="identifier">relaxed</span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order_release</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order</span><span class="special">::</span><span class="identifier">release</span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order_acquire</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order</span><span class="special">::</span><span class="identifier">acquire</span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order_consume</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order</span><span class="special">::</span><span class="identifier">consume</span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order_acq_rel</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order</span><span class="special">::</span><span class="identifier">acq_rel</span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order_seq_cst</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">memory_order</span><span class="special">::</span><span class="identifier">seq_cst</span></code> + </p> + </td> +</tr> +</tbody> +</table></div> +<p> See section <a class="link" href="thread_coordination.html" title="Thread coordination using Boost.Atomic"><span class="emphasis"><em>happens-before</em></span></a> for explanation of the various ordering constraints. </p> @@ -434,6 +544,8 @@ template class</a></span></dt> <dt><span class="section"><a href="interface.html#atomic.interface.interface_atomic_object.interface_atomic_integral"><code class="literal">boost::atomic<<span class="emphasis"><em>integral</em></span>></code> template class</a></span></dt> +<dt><span class="section"><a href="interface.html#atomic.interface.interface_atomic_object.interface_atomic_floating_point"><code class="literal">boost::atomic<<span class="emphasis"><em>floating-point</em></span>></code> + template class</a></span></dt> <dt><span class="section"><a href="interface.html#atomic.interface.interface_atomic_object.interface_atomic_pointer"><code class="literal">boost::atomic<<span class="emphasis"><em>pointer</em></span>></code> template class</a></span></dt> <dt><span class="section"><a href="interface.html#atomic.interface.interface_atomic_object.interface_atomic_convenience_typedefs"><code class="literal">boost::atomic<<span class="emphasis"><em>T</em></span>></code> @@ -462,7 +574,8 @@ Note that classes with virtual functions or virtual base classes do not satisfy the requirements. Also be warned that structures with "padding" between data members may compare non-equal via <code class="literal">memcmp</code> - even though all members are equal. + even though all members are equal. This may also be the case with some floating + point types, which include padding bits themselves. </p> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> @@ -679,8 +792,8 @@ In addition to these explicit operations, each <code class="literal">atomic<<span class="emphasis"><em>T</em></span>></code> object also supports implicit <code class="literal">store</code> and <code class="literal">load</code> through the use of "assignment" and "conversion to <code class="literal">T</code>" - operators. Avoid using these operators, as they do not allow explicit specification - of a memory ordering constraint. + operators. Avoid using these operators, as they do not allow to specify + a memory ordering constraint which always defaults to <code class="computeroutput"><span class="identifier">memory_order_seq_cst</span></code>. </p> </div> <div class="section"> @@ -841,28 +954,117 @@ <tr> <td> <p> - <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_negate</span><span class="special">(</span><span class="identifier">memory_order</span> + <code class="computeroutput"><span class="identifier">I</span> <span class="identifier">negate</span><span class="special">(</span><span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> </p> </td> <td> <p> Change the sign of the value stored in the variable, returning - nothing + the result </p> </td> </tr> <tr> <td> <p> - <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_complement</span><span class="special">(</span><span class="identifier">memory_order</span> + <code class="computeroutput"><span class="identifier">I</span> <span class="identifier">add</span><span class="special">(</span><span class="identifier">I</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Add <code class="computeroutput"><span class="identifier">v</span></code> to variable, + returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">I</span> <span class="identifier">sub</span><span class="special">(</span><span class="identifier">I</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Subtract <code class="computeroutput"><span class="identifier">v</span></code> from + variable, returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">I</span> <span class="identifier">bitwise_and</span><span class="special">(</span><span class="identifier">I</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Apply bit-wise "and" with <code class="computeroutput"><span class="identifier">v</span></code> + to variable, returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">I</span> <span class="identifier">bitwise_or</span><span class="special">(</span><span class="identifier">I</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Apply bit-wise "or" with <code class="computeroutput"><span class="identifier">v</span></code> + to variable, returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">I</span> <span class="identifier">bitwise_xor</span><span class="special">(</span><span class="identifier">I</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Apply bit-wise "xor" with <code class="computeroutput"><span class="identifier">v</span></code> + to variable, returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">I</span> <span class="identifier">bitwise_complement</span><span class="special">(</span><span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> </p> </td> <td> <p> Set the variable to the one's complement of the current value, - returning nothing + returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_negate</span><span class="special">(</span><span class="identifier">memory_order</span> + <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Change the sign of the value stored in the variable, returning + nothing </p> </td> </tr> @@ -944,6 +1146,36 @@ <tr> <td> <p> + <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_complement</span><span class="special">(</span><span class="identifier">memory_order</span> + <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Set the variable to the one's complement of the current value, + returning nothing + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">negate_and_test</span><span class="special">(</span><span class="identifier">memory_order</span> + <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Change the sign of the value stored in the variable, returning + <code class="computeroutput"><span class="keyword">true</span></code> if the result + is non-zero and <code class="computeroutput"><span class="keyword">false</span></code> + otherwise + </p> + </td> +</tr> +<tr> +<td> + <p> <code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">add_and_test</span><span class="special">(</span><span class="identifier">I</span> <span class="identifier">v</span><span class="special">,</span> <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> @@ -953,7 +1185,7 @@ <p> Add <code class="computeroutput"><span class="identifier">v</span></code> to variable, returning <code class="computeroutput"><span class="keyword">true</span></code> if - the result is zero and <code class="computeroutput"><span class="keyword">false</span></code> + the result is non-zero and <code class="computeroutput"><span class="keyword">false</span></code> otherwise </p> </td> @@ -970,7 +1202,7 @@ <p> Subtract <code class="computeroutput"><span class="identifier">v</span></code> from variable, returning <code class="computeroutput"><span class="keyword">true</span></code> - if the result is zero and <code class="computeroutput"><span class="keyword">false</span></code> + if the result is non-zero and <code class="computeroutput"><span class="keyword">false</span></code> otherwise </p> </td> @@ -987,7 +1219,7 @@ <p> Apply bit-wise "and" with <code class="computeroutput"><span class="identifier">v</span></code> to variable, returning <code class="computeroutput"><span class="keyword">true</span></code> - if the result is zero and <code class="computeroutput"><span class="keyword">false</span></code> + if the result is non-zero and <code class="computeroutput"><span class="keyword">false</span></code> otherwise </p> </td> @@ -1004,7 +1236,7 @@ <p> Apply bit-wise "or" with <code class="computeroutput"><span class="identifier">v</span></code> to variable, returning <code class="computeroutput"><span class="keyword">true</span></code> - if the result is zero and <code class="computeroutput"><span class="keyword">false</span></code> + if the result is non-zero and <code class="computeroutput"><span class="keyword">false</span></code> otherwise </p> </td> @@ -1021,7 +1253,23 @@ <p> Apply bit-wise "xor" with <code class="computeroutput"><span class="identifier">v</span></code> to variable, returning <code class="computeroutput"><span class="keyword">true</span></code> - if the result is zero and <code class="computeroutput"><span class="keyword">false</span></code> + if the result is non-zero and <code class="computeroutput"><span class="keyword">false</span></code> + otherwise + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">complement_and_test</span><span class="special">(</span><span class="identifier">memory_order</span> + <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Set the variable to the one's complement of the current value, + returning <code class="computeroutput"><span class="keyword">true</span></code> if + the result is non-zero and <code class="computeroutput"><span class="keyword">false</span></code> otherwise </p> </td> @@ -1079,6 +1327,25 @@ </tr> </tbody> </table></div> +<div class="note"><table border="0" summary="Note"> +<tr> +<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td> +<th align="left">Note</th> +</tr> +<tr><td align="left" valign="top"><p> + In Boost.Atomic 1.66 the <code class="literal"><span class="emphasis"><em>op</em></span>_and_test</code> + operations returned the opposite value (i.e. <code class="computeroutput"><span class="keyword">true</span></code> + if the result is zero). This was changed to the current behavior in 1.67 + for consistency with other operations in Boost.Atomic, as well as with + conventions taken in the C++ standard library. Boost.Atomic 1.66 was + the only release shipped with the old behavior. Users upgrading from + Boost 1.66 to a later release can define <code class="computeroutput"><span class="identifier">BOOST_ATOMIC_HIGHLIGHT_OP_AND_TEST</span></code> + macro when building their code to generate deprecation warnings on the + <code class="literal"><span class="emphasis"><em>op</em></span>_and_test</code> function calls (the + functions are not actually deprecated though; this is just a way to highlight + their use). + </p></td></tr> +</table></div> <p> <code class="computeroutput"><span class="identifier">order</span></code> always has <code class="computeroutput"><span class="identifier">memory_order_seq_cst</span></code> as default parameter. </p> @@ -1096,8 +1363,240 @@ object also supports implicit pre-/post- increment/decrement, as well as the operators <code class="computeroutput"><span class="special">+=</span></code>, <code class="computeroutput"><span class="special">-=</span></code>, <code class="computeroutput"><span class="special">&=</span></code>, <code class="computeroutput"><span class="special">|=</span></code> and <code class="computeroutput"><span class="special">^=</span></code>. - Avoid using these operators, as they do not allow explicit specification - of a memory ordering constraint which always defaults to <code class="computeroutput"><span class="identifier">memory_order_seq_cst</span></code>. + Avoid using these operators, as they do not allow to specify a memory ordering + constraint which always defaults to <code class="computeroutput"><span class="identifier">memory_order_seq_cst</span></code>. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h4 class="title"> +<a name="atomic.interface.interface_atomic_object.interface_atomic_floating_point"></a><a class="link" href="interface.html#atomic.interface.interface_atomic_object.interface_atomic_floating_point" title="boost::atomic<floating-point> template class"><code class="literal">boost::atomic<<span class="emphasis"><em>floating-point</em></span>></code> + template class</a> +</h4></div></div></div> +<div class="note"><table border="0" summary="Note"> +<tr> +<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td> +<th align="left">Note</th> +</tr> +<tr><td align="left" valign="top"><p> + The support for floating point types is optional and can be disabled + by defining <code class="computeroutput"><span class="identifier">BOOST_ATOMIC_NO_FLOATING_POINT</span></code>. + </p></td></tr> +</table></div> +<p> + In addition to the operations applicable to all atomic objects, <code class="literal">boost::atomic<<span class="emphasis"><em>F</em></span>></code> + for floating point types <code class="literal"><span class="emphasis"><em>F</em></span></code> supports + the following operations, which correspond to <code class="literal">std::atomic<<span class="emphasis"><em>F</em></span>></code>: + </p> +<div class="informaltable"><table class="table"> +<colgroup> +<col> +<col> +</colgroup> +<thead><tr> +<th> + <p> + Syntax + </p> + </th> +<th> + <p> + Description + </p> + </th> +</tr></thead> +<tbody> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">F</span> <span class="identifier">fetch_add</span><span class="special">(</span><span class="identifier">F</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Add <code class="computeroutput"><span class="identifier">v</span></code> to variable, + returning previous value + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">F</span> <span class="identifier">fetch_sub</span><span class="special">(</span><span class="identifier">F</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Subtract <code class="computeroutput"><span class="identifier">v</span></code> from + variable, returning previous value + </p> + </td> +</tr> +</tbody> +</table></div> +<p> + Additionally, as a <span class="bold"><strong>Boost.Atomic</strong></span> extension, + the following operations are also provided: + </p> +<div class="informaltable"><table class="table"> +<colgroup> +<col> +<col> +</colgroup> +<thead><tr> +<th> + <p> + Syntax + </p> + </th> +<th> + <p> + Description + </p> + </th> +</tr></thead> +<tbody> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">F</span> <span class="identifier">fetch_negate</span><span class="special">(</span><span class="identifier">memory_order</span> + <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Change the sign of the value stored in the variable, returning + previous value + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">F</span> <span class="identifier">negate</span><span class="special">(</span><span class="identifier">memory_order</span> + <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Change the sign of the value stored in the variable, returning + the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">F</span> <span class="identifier">add</span><span class="special">(</span><span class="identifier">F</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Add <code class="computeroutput"><span class="identifier">v</span></code> to variable, + returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">F</span> <span class="identifier">sub</span><span class="special">(</span><span class="identifier">F</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Subtract <code class="computeroutput"><span class="identifier">v</span></code> from + variable, returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_negate</span><span class="special">(</span><span class="identifier">memory_order</span> + <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Change the sign of the value stored in the variable, returning + nothing + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_add</span><span class="special">(</span><span class="identifier">F</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Add <code class="computeroutput"><span class="identifier">v</span></code> to variable, + returning nothing + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_sub</span><span class="special">(</span><span class="identifier">F</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Subtract <code class="computeroutput"><span class="identifier">v</span></code> from + variable, returning nothing + </p> + </td> +</tr> +</tbody> +</table></div> +<p> + <code class="computeroutput"><span class="identifier">order</span></code> always has <code class="computeroutput"><span class="identifier">memory_order_seq_cst</span></code> as default parameter. + </p> +<p> + The <code class="literal">opaque_<span class="emphasis"><em>op</em></span></code> variants of the operations + may result in a more efficient code on some architectures because the original + value of the atomic variable is not preserved. + </p> +<p> + In addition to these explicit operations, each <code class="literal">boost::atomic<<span class="emphasis"><em>F</em></span>></code> + object also supports operators <code class="computeroutput"><span class="special">+=</span></code> + and <code class="computeroutput"><span class="special">-=</span></code>. Avoid using these + operators, as they do not allow to specify a memory ordering constraint + which always defaults to <code class="computeroutput"><span class="identifier">memory_order_seq_cst</span></code>. + </p> +<p> + When using atomic operations with floating point types, bear in mind that + <span class="bold"><strong>Boost.Atomic</strong></span> always performs bitwise comparison + of the stored values. This means that operations like <code class="computeroutput"><span class="identifier">compare_exchange</span><span class="special">*</span></code> may fail if the stored value and comparand + have different binary representation, even if they would normally compare + equal. This is typically the case when either of the numbers is <a href="https://en.wikipedia.org/wiki/Denormal_number" target="_top">denormalized</a>. + This also means that the behavior with regard to special floating point + values like NaN and signed zero is also different from normal C++. + </p> +<p> + Another source of the problem is padding bits that are added to some floating + point types for alignment. One widespread example of that is Intel x87 + extended double format, which is typically stored as 80 bits of value padded + with 16 or 48 unused bits. These padding bits are often uninitialized and + contain garbage, which makes two equal numbers have different binary representation. + The library attempts to account for the known such cases, but in general + it is possible that some platforms are not covered. Note that the C++ standard + makes no guarantees about reliability of <code class="computeroutput"><span class="identifier">compare_exchange</span><span class="special">*</span></code> operations in the face of padding or trap + bits. </p> </div> <div class="section"> @@ -1106,7 +1605,7 @@ template class</a> </h4></div></div></div> <p> - In addition to the operations applicable to all atomic object, <code class="literal">boost::atomic<<span class="emphasis"><em>P</em></span>></code> + In addition to the operations applicable to all atomic objects, <code class="literal">boost::atomic<<span class="emphasis"><em>P</em></span>></code> for pointer types <code class="literal"><span class="emphasis"><em>P</em></span></code> (other than pointers to <code class="literal">void</code>, function or member pointers) support the following operations, which correspond to <code class="literal">std::atomic<<span class="emphasis"><em>P</em></span>></code>: @@ -1186,6 +1685,36 @@ <tr> <td> <p> + <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">add</span><span class="special">(</span><span class="identifier">ptrdiff_t</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Add <code class="computeroutput"><span class="identifier">v</span></code> to variable, + returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">sub</span><span class="special">(</span><span class="identifier">ptrdiff_t</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Subtract <code class="computeroutput"><span class="identifier">v</span></code> from + variable, returning the result + </p> + </td> +</tr> +<tr> +<td> + <p> <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">opaque_add</span><span class="special">(</span><span class="identifier">ptrdiff_t</span> <span class="identifier">v</span><span class="special">,</span> <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> @@ -1213,6 +1742,40 @@ </p> </td> </tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">add_and_test</span><span class="special">(</span><span class="identifier">ptrdiff_t</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Add <code class="computeroutput"><span class="identifier">v</span></code> to variable, + returning <code class="computeroutput"><span class="keyword">true</span></code> if + the result is non-null and <code class="computeroutput"><span class="keyword">false</span></code> + otherwise + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">sub_and_test</span><span class="special">(</span><span class="identifier">ptrdiff_t</span> + <span class="identifier">v</span><span class="special">,</span> + <span class="identifier">memory_order</span> <span class="identifier">order</span><span class="special">)</span></code> + </p> + </td> +<td> + <p> + Subtract <code class="computeroutput"><span class="identifier">v</span></code> from + variable, returning <code class="computeroutput"><span class="keyword">true</span></code> + if the result is non-null and <code class="computeroutput"><span class="keyword">false</span></code> + otherwise + </p> + </td> +</tr> </tbody> </table></div> <p> @@ -1658,11 +2221,76 @@ is a type that fits storage of contiguous <code class="computeroutput"><span class="identifier">N</span></code> bits, suitably aligned for atomic operations. </p> +<p> + For floating-point types the following macros are similarly defined: + </p> +<div class="informaltable"><table class="table"> +<colgroup> +<col> +<col> +</colgroup> +<thead><tr> +<th> + <p> + Macro + </p> + </th> +<th> + <p> + Description + </p> + </th> +</tr></thead> +<tbody> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">BOOST_ATOMIC_FLOAT_LOCK_FREE</span></code> + </p> + </td> +<td> + <p> + Indicate whether <code class="computeroutput"><span class="identifier">atomic</span><span class="special"><</span><span class="keyword">float</span><span class="special">></span></code> is lock-free. + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">BOOST_ATOMIC_DOUBLE_LOCK_FREE</span></code> + </p> + </td> +<td> + <p> + Indicate whether <code class="computeroutput"><span class="identifier">atomic</span><span class="special"><</span><span class="keyword">double</span><span class="special">></span></code> is lock-free. + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">BOOST_ATOMIC_LONG_DOUBLE_LOCK_FREE</span></code> + </p> + </td> +<td> + <p> + Indicate whether <code class="computeroutput"><span class="identifier">atomic</span><span class="special"><</span><span class="keyword">long</span> + <span class="keyword">double</span><span class="special">></span></code> + is lock-free. + </p> + </td> +</tr> +</tbody> +</table></div> +<p> + These macros are not defined when support for floating point types is disabled + by user. + </p> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> -<td align="right"><div class="copyright-footer">Copyright © 2011 Helge Bahmann<br>Copyright © 2012 Tim Blechmann<br>Copyright © 2013, 2017 Andrey Semashev<p> +<td align="right"><div class="copyright-footer">Copyright © 2011 Helge Bahmann<br>Copyright © 2012 Tim Blechmann<br>Copyright © 2013, 2017, 2018 Andrey Semashev<p> Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </p> |