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  70. <a name="Fixed_002dPoint"></a>

  71. <div class="header">

  72. <p>

  73. Next: <a href="Named-Address-Spaces.html#Named-Address-Spaces" accesskey="n" rel="next">Named Address Spaces</a>, Previous: <a href="Hex-Floats.html#Hex-Floats" accesskey="p" rel="prev">Hex Floats</a>, Up: <a href="C-Extensions.html#C-Extensions" accesskey="u" rel="up">C Extensions</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>

  74. </div>

  75. <hr>

  76. <a name="Fixed_002dPoint-Types"></a>

  77. <h3 class="section">6.16 Fixed-Point Types</h3>

  78. <a name="index-fixed_002dpoint-types"></a>

  79. <a name="index-_005fFract-data-type"></a>

  80. <a name="index-_005fAccum-data-type"></a>

  81. <a name="index-_005fSat-data-type"></a>

  82. <a name="index-hr-fixed_002dsuffix"></a>

  83. <a name="index-r-fixed_002dsuffix"></a>

  84. <a name="index-lr-fixed_002dsuffix"></a>

  85. <a name="index-llr-fixed_002dsuffix"></a>

  86. <a name="index-uhr-fixed_002dsuffix"></a>

  87. <a name="index-ur-fixed_002dsuffix"></a>

  88. <a name="index-ulr-fixed_002dsuffix"></a>

  89. <a name="index-ullr-fixed_002dsuffix"></a>

  90. <a name="index-hk-fixed_002dsuffix"></a>

  91. <a name="index-k-fixed_002dsuffix"></a>

  92. <a name="index-lk-fixed_002dsuffix"></a>

  93. <a name="index-llk-fixed_002dsuffix"></a>

  94. <a name="index-uhk-fixed_002dsuffix"></a>

  95. <a name="index-uk-fixed_002dsuffix"></a>

  96. <a name="index-ulk-fixed_002dsuffix"></a>

  97. <a name="index-ullk-fixed_002dsuffix"></a>

  98. <a name="index-HR-fixed_002dsuffix"></a>

  99. <a name="index-R-fixed_002dsuffix"></a>

  100. <a name="index-LR-fixed_002dsuffix"></a>

  101. <a name="index-LLR-fixed_002dsuffix"></a>

  102. <a name="index-UHR-fixed_002dsuffix"></a>

  103. <a name="index-UR-fixed_002dsuffix"></a>

  104. <a name="index-ULR-fixed_002dsuffix"></a>

  105. <a name="index-ULLR-fixed_002dsuffix"></a>

  106. <a name="index-HK-fixed_002dsuffix"></a>

  107. <a name="index-K-fixed_002dsuffix"></a>

  108. <a name="index-LK-fixed_002dsuffix"></a>

  109. <a name="index-LLK-fixed_002dsuffix"></a>

  110. <a name="index-UHK-fixed_002dsuffix"></a>

  111. <a name="index-UK-fixed_002dsuffix"></a>

  112. <a name="index-ULK-fixed_002dsuffix"></a>

  113. <a name="index-ULLK-fixed_002dsuffix"></a>

  114. 

  115. <p>As an extension, GNU C supports fixed-point types as

  116. defined in the N1169 draft of ISO/IEC DTR 18037.  Support for fixed-point

  117. types in GCC will evolve as the draft technical report changes.

  118. Calling conventions for any target might also change.  Not all targets

  119. support fixed-point types.

  120. </p>

  121. <p>The fixed-point types are

  122. <code>short _Fract</code>,

  123. <code>_Fract</code>,

  124. <code>long _Fract</code>,

  125. <code>long long _Fract</code>,

  126. <code>unsigned short _Fract</code>,

  127. <code>unsigned _Fract</code>,

  128. <code>unsigned long _Fract</code>,

  129. <code>unsigned long long _Fract</code>,

  130. <code>_Sat short _Fract</code>,

  131. <code>_Sat _Fract</code>,

  132. <code>_Sat long _Fract</code>,

  133. <code>_Sat long long _Fract</code>,

  134. <code>_Sat unsigned short _Fract</code>,

  135. <code>_Sat unsigned _Fract</code>,

  136. <code>_Sat unsigned long _Fract</code>,

  137. <code>_Sat unsigned long long _Fract</code>,

  138. <code>short _Accum</code>,

  139. <code>_Accum</code>,

  140. <code>long _Accum</code>,

  141. <code>long long _Accum</code>,

  142. <code>unsigned short _Accum</code>,

  143. <code>unsigned _Accum</code>,

  144. <code>unsigned long _Accum</code>,

  145. <code>unsigned long long _Accum</code>,

  146. <code>_Sat short _Accum</code>,

  147. <code>_Sat _Accum</code>,

  148. <code>_Sat long _Accum</code>,

  149. <code>_Sat long long _Accum</code>,

  150. <code>_Sat unsigned short _Accum</code>,

  151. <code>_Sat unsigned _Accum</code>,

  152. <code>_Sat unsigned long _Accum</code>,

  153. <code>_Sat unsigned long long _Accum</code>.

  154. </p>

  155. <p>Fixed-point data values contain fractional and optional integral parts.

  156. The format of fixed-point data varies and depends on the target machine.

  157. </p>

  158. <p>Support for fixed-point types includes:

  159. </p><ul>

  160. <li> prefix and postfix increment and decrement operators (<code>++</code>, <code>--</code>)

  161. </li><li> unary arithmetic operators (<code>+</code>, <code>-</code>, <code>!</code>)

  162. </li><li> binary arithmetic operators (<code>+</code>, <code>-</code>, <code>*</code>, <code>/</code>)

  163. </li><li> binary shift operators (<code>&lt;&lt;</code>, <code>&gt;&gt;</code>)

  164. </li><li> relational operators (<code>&lt;</code>, <code>&lt;=</code>, <code>&gt;=</code>, <code>&gt;</code>)

  165. </li><li> equality operators (<code>==</code>, <code>!=</code>)

  166. </li><li> assignment operators (<code>+=</code>, <code>-=</code>, <code>*=</code>, <code>/=</code>,

  167. <code>&lt;&lt;=</code>, <code>&gt;&gt;=</code>)

  168. </li><li> conversions to and from integer, floating-point, or fixed-point types

  169. </li></ul>

  170. 

  171. <p>Use a suffix in a fixed-point literal constant:

  172. </p><ul>

  173. <li> &lsquo;<samp>hr</samp>&rsquo; or &lsquo;<samp>HR</samp>&rsquo; for <code>short _Fract</code> and

  174. <code>_Sat short _Fract</code>

  175. </li><li> &lsquo;<samp>r</samp>&rsquo; or &lsquo;<samp>R</samp>&rsquo; for <code>_Fract</code> and <code>_Sat _Fract</code>

  176. </li><li> &lsquo;<samp>lr</samp>&rsquo; or &lsquo;<samp>LR</samp>&rsquo; for <code>long _Fract</code> and

  177. <code>_Sat long _Fract</code>

  178. </li><li> &lsquo;<samp>llr</samp>&rsquo; or &lsquo;<samp>LLR</samp>&rsquo; for <code>long long _Fract</code> and

  179. <code>_Sat long long _Fract</code>

  180. </li><li> &lsquo;<samp>uhr</samp>&rsquo; or &lsquo;<samp>UHR</samp>&rsquo; for <code>unsigned short _Fract</code> and

  181. <code>_Sat unsigned short _Fract</code>

  182. </li><li> &lsquo;<samp>ur</samp>&rsquo; or &lsquo;<samp>UR</samp>&rsquo; for <code>unsigned _Fract</code> and

  183. <code>_Sat unsigned _Fract</code>

  184. </li><li> &lsquo;<samp>ulr</samp>&rsquo; or &lsquo;<samp>ULR</samp>&rsquo; for <code>unsigned long _Fract</code> and

  185. <code>_Sat unsigned long _Fract</code>

  186. </li><li> &lsquo;<samp>ullr</samp>&rsquo; or &lsquo;<samp>ULLR</samp>&rsquo; for <code>unsigned long long _Fract</code>

  187. and <code>_Sat unsigned long long _Fract</code>

  188. </li><li> &lsquo;<samp>hk</samp>&rsquo; or &lsquo;<samp>HK</samp>&rsquo; for <code>short _Accum</code> and

  189. <code>_Sat short _Accum</code>

  190. </li><li> &lsquo;<samp>k</samp>&rsquo; or &lsquo;<samp>K</samp>&rsquo; for <code>_Accum</code> and <code>_Sat _Accum</code>

  191. </li><li> &lsquo;<samp>lk</samp>&rsquo; or &lsquo;<samp>LK</samp>&rsquo; for <code>long _Accum</code> and

  192. <code>_Sat long _Accum</code>

  193. </li><li> &lsquo;<samp>llk</samp>&rsquo; or &lsquo;<samp>LLK</samp>&rsquo; for <code>long long _Accum</code> and

  194. <code>_Sat long long _Accum</code>

  195. </li><li> &lsquo;<samp>uhk</samp>&rsquo; or &lsquo;<samp>UHK</samp>&rsquo; for <code>unsigned short _Accum</code> and

  196. <code>_Sat unsigned short _Accum</code>

  197. </li><li> &lsquo;<samp>uk</samp>&rsquo; or &lsquo;<samp>UK</samp>&rsquo; for <code>unsigned _Accum</code> and

  198. <code>_Sat unsigned _Accum</code>

  199. </li><li> &lsquo;<samp>ulk</samp>&rsquo; or &lsquo;<samp>ULK</samp>&rsquo; for <code>unsigned long _Accum</code> and

  200. <code>_Sat unsigned long _Accum</code>

  201. </li><li> &lsquo;<samp>ullk</samp>&rsquo; or &lsquo;<samp>ULLK</samp>&rsquo; for <code>unsigned long long _Accum</code>

  202. and <code>_Sat unsigned long long _Accum</code>

  203. </li></ul>

  204. 

  205. <p>GCC support of fixed-point types as specified by the draft technical report

  206. is incomplete:

  207. </p>

  208. <ul>

  209. <li> Pragmas to control overflow and rounding behaviors are not implemented.

  210. </li></ul>

  211. 

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

  213. </p>

  214. <hr>

  215. <div class="header">

  216. <p>

  217. Next: <a href="Named-Address-Spaces.html#Named-Address-Spaces" accesskey="n" rel="next">Named Address Spaces</a>, Previous: <a href="Hex-Floats.html#Hex-Floats" accesskey="p" rel="prev">Hex Floats</a>, Up: <a href="C-Extensions.html#C-Extensions" accesskey="u" rel="up">C Extensions</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>

  218. </div>

  219. 

  220. 

  221. 

  222. </body>

  223. </html>