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<a name="Fixed_002dPoint"></a>
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<a name="Fixed_002dPoint-Types"></a>
<h3 class="section">6.16 Fixed-Point Types</h3>
<a name="index-fixed_002dpoint-types"></a>
<a name="index-_005fFract-data-type"></a>
<a name="index-_005fAccum-data-type"></a>
<a name="index-_005fSat-data-type"></a>
<a name="index-hr-fixed_002dsuffix"></a>
<a name="index-r-fixed_002dsuffix"></a>
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<p>As an extension, GNU C supports fixed-point types as
defined in the N1169 draft of ISO/IEC DTR 18037.  Support for fixed-point
types in GCC will evolve as the draft technical report changes.
Calling conventions for any target might also change.  Not all targets
support fixed-point types.
</p>
<p>The fixed-point types are
<code>short _Fract</code>,
<code>_Fract</code>,
<code>long _Fract</code>,
<code>long long _Fract</code>,
<code>unsigned short _Fract</code>,
<code>unsigned _Fract</code>,
<code>unsigned long _Fract</code>,
<code>unsigned long long _Fract</code>,
<code>_Sat short _Fract</code>,
<code>_Sat _Fract</code>,
<code>_Sat long _Fract</code>,
<code>_Sat long long _Fract</code>,
<code>_Sat unsigned short _Fract</code>,
<code>_Sat unsigned _Fract</code>,
<code>_Sat unsigned long _Fract</code>,
<code>_Sat unsigned long long _Fract</code>,
<code>short _Accum</code>,
<code>_Accum</code>,
<code>long _Accum</code>,
<code>long long _Accum</code>,
<code>unsigned short _Accum</code>,
<code>unsigned _Accum</code>,
<code>unsigned long _Accum</code>,
<code>unsigned long long _Accum</code>,
<code>_Sat short _Accum</code>,
<code>_Sat _Accum</code>,
<code>_Sat long _Accum</code>,
<code>_Sat long long _Accum</code>,
<code>_Sat unsigned short _Accum</code>,
<code>_Sat unsigned _Accum</code>,
<code>_Sat unsigned long _Accum</code>,
<code>_Sat unsigned long long _Accum</code>.
</p>
<p>Fixed-point data values contain fractional and optional integral parts.
The format of fixed-point data varies and depends on the target machine.
</p>
<p>Support for fixed-point types includes:
</p><ul>
<li> prefix and postfix increment and decrement operators (<code>++</code>, <code>--</code>)
</li><li> unary arithmetic operators (<code>+</code>, <code>-</code>, <code>!</code>)
</li><li> binary arithmetic operators (<code>+</code>, <code>-</code>, <code>*</code>, <code>/</code>)
</li><li> binary shift operators (<code>&lt;&lt;</code>, <code>&gt;&gt;</code>)
</li><li> relational operators (<code>&lt;</code>, <code>&lt;=</code>, <code>&gt;=</code>, <code>&gt;</code>)
</li><li> equality operators (<code>==</code>, <code>!=</code>)
</li><li> assignment operators (<code>+=</code>, <code>-=</code>, <code>*=</code>, <code>/=</code>,
<code>&lt;&lt;=</code>, <code>&gt;&gt;=</code>)
</li><li> conversions to and from integer, floating-point, or fixed-point types
</li></ul>

<p>Use a suffix in a fixed-point literal constant:
</p><ul>
<li> &lsquo;<samp>hr</samp>&rsquo; or &lsquo;<samp>HR</samp>&rsquo; for <code>short _Fract</code> and
<code>_Sat short _Fract</code>
</li><li> &lsquo;<samp>r</samp>&rsquo; or &lsquo;<samp>R</samp>&rsquo; for <code>_Fract</code> and <code>_Sat _Fract</code>
</li><li> &lsquo;<samp>lr</samp>&rsquo; or &lsquo;<samp>LR</samp>&rsquo; for <code>long _Fract</code> and
<code>_Sat long _Fract</code>
</li><li> &lsquo;<samp>llr</samp>&rsquo; or &lsquo;<samp>LLR</samp>&rsquo; for <code>long long _Fract</code> and
<code>_Sat long long _Fract</code>
</li><li> &lsquo;<samp>uhr</samp>&rsquo; or &lsquo;<samp>UHR</samp>&rsquo; for <code>unsigned short _Fract</code> and
<code>_Sat unsigned short _Fract</code>
</li><li> &lsquo;<samp>ur</samp>&rsquo; or &lsquo;<samp>UR</samp>&rsquo; for <code>unsigned _Fract</code> and
<code>_Sat unsigned _Fract</code>
</li><li> &lsquo;<samp>ulr</samp>&rsquo; or &lsquo;<samp>ULR</samp>&rsquo; for <code>unsigned long _Fract</code> and
<code>_Sat unsigned long _Fract</code>
</li><li> &lsquo;<samp>ullr</samp>&rsquo; or &lsquo;<samp>ULLR</samp>&rsquo; for <code>unsigned long long _Fract</code>
and <code>_Sat unsigned long long _Fract</code>
</li><li> &lsquo;<samp>hk</samp>&rsquo; or &lsquo;<samp>HK</samp>&rsquo; for <code>short _Accum</code> and
<code>_Sat short _Accum</code>
</li><li> &lsquo;<samp>k</samp>&rsquo; or &lsquo;<samp>K</samp>&rsquo; for <code>_Accum</code> and <code>_Sat _Accum</code>
</li><li> &lsquo;<samp>lk</samp>&rsquo; or &lsquo;<samp>LK</samp>&rsquo; for <code>long _Accum</code> and
<code>_Sat long _Accum</code>
</li><li> &lsquo;<samp>llk</samp>&rsquo; or &lsquo;<samp>LLK</samp>&rsquo; for <code>long long _Accum</code> and
<code>_Sat long long _Accum</code>
</li><li> &lsquo;<samp>uhk</samp>&rsquo; or &lsquo;<samp>UHK</samp>&rsquo; for <code>unsigned short _Accum</code> and
<code>_Sat unsigned short _Accum</code>
</li><li> &lsquo;<samp>uk</samp>&rsquo; or &lsquo;<samp>UK</samp>&rsquo; for <code>unsigned _Accum</code> and
<code>_Sat unsigned _Accum</code>
</li><li> &lsquo;<samp>ulk</samp>&rsquo; or &lsquo;<samp>ULK</samp>&rsquo; for <code>unsigned long _Accum</code> and
<code>_Sat unsigned long _Accum</code>
</li><li> &lsquo;<samp>ullk</samp>&rsquo; or &lsquo;<samp>ULLK</samp>&rsquo; for <code>unsigned long long _Accum</code>
and <code>_Sat unsigned long long _Accum</code>
</li></ul>

<p>GCC support of fixed-point types as specified by the draft technical report
is incomplete:
</p>
<ul>
<li> Pragmas to control overflow and rounding behaviors are not implemented.
</li></ul>

<p>Fixed-point types are supported by the DWARF debug information format.
</p>
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