78 lines
3.5 KiB
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78 lines
3.5 KiB
HTML
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<title>OpenRISC-Regs - Using as</title>
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<link rel="up" href="OpenRISC_002dSyntax.html#OpenRISC_002dSyntax" title="OpenRISC-Syntax">
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<!--
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This file documents the GNU Assembler "as".
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Copyright (C) 1991-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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<div class="node">
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<a name="OpenRISC-Regs"></a>
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<a name="OpenRISC_002dRegs"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="OpenRISC_002dRelocs.html#OpenRISC_002dRelocs">OpenRISC-Relocs</a>,
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Previous: <a rel="previous" accesskey="p" href="OpenRISC_002dChars.html#OpenRISC_002dChars">OpenRISC-Chars</a>,
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Up: <a rel="up" accesskey="u" href="OpenRISC_002dSyntax.html#OpenRISC_002dSyntax">OpenRISC-Syntax</a>
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<hr>
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</div>
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<h5 class="subsubsection">9.33.1.2 Register Names</h5>
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<p><a name="index-OpenRISC-registers-1838"></a><a name="index-register-names_002c-OpenRISC-1839"></a>
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The OpenRISC register file contains 32 general pupose registers.
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<ul>
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<li>The 32 general purpose registers are referred to as ‘<samp><span class="samp">r</span><var>n</var></samp>’.
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<li>The stack pointer register ‘<samp><span class="samp">r1</span></samp>’ can be referenced using the alias
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‘<samp><span class="samp">sp</span></samp>’.
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<li>The frame pointer register ‘<samp><span class="samp">r2</span></samp>’ can be referenced using the alias
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‘<samp><span class="samp">fp</span></samp>’.
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<li>The link register ‘<samp><span class="samp">r9</span></samp>’ can be referenced using the alias ‘<samp><span class="samp">lr</span></samp>’.
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</ul>
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<p>Floating point operations use the same general purpose registers. The
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instructions <code>lf.itof.s</code> (single precision) and <code>lf.itof.d</code> (double
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precision) can be used to convert integer values to floating point.
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Likewise, instructions <code>lf.ftoi.s</code> (single precision) and
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<code>lf.ftoi.d</code> (double precision) can be used to convert floating point to
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integer.
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<p>OpenRISC also contains privileged special purpose registers (SPRs). The
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SPRs are accessed using the <code>l.mfspr</code> and <code>l.mtspr</code> instructions.
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