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| <h5 class="subsubsection">9.33.1.2 Register Names</h5> |
| |
| <p><a name="index-OpenRISC-registers-1838"></a><a name="index-register-names_002c-OpenRISC-1839"></a> |
| The OpenRISC register file contains 32 general pupose registers. |
| |
| <ul> |
| <li>The 32 general purpose registers are referred to as ‘<samp><span class="samp">r</span><var>n</var></samp>’. |
| |
| <li>The stack pointer register ‘<samp><span class="samp">r1</span></samp>’ can be referenced using the alias |
| ‘<samp><span class="samp">sp</span></samp>’. |
| |
| <li>The frame pointer register ‘<samp><span class="samp">r2</span></samp>’ can be referenced using the alias |
| ‘<samp><span class="samp">fp</span></samp>’. |
| |
| <li>The link register ‘<samp><span class="samp">r9</span></samp>’ can be referenced using the alias ‘<samp><span class="samp">lr</span></samp>’. |
| </ul> |
| |
| <p>Floating point operations use the same general purpose registers. The |
| instructions <code>lf.itof.s</code> (single precision) and <code>lf.itof.d</code> (double |
| precision) can be used to convert integer values to floating point. |
| Likewise, instructions <code>lf.ftoi.s</code> (single precision) and |
| <code>lf.ftoi.d</code> (double precision) can be used to convert floating point to |
| integer. |
| |
| <p>OpenRISC also contains privileged special purpose registers (SPRs). The |
| SPRs are accessed using the <code>l.mfspr</code> and <code>l.mtspr</code> instructions. |
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