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111 lines
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111 lines
5.3 KiB
HTML
4 years ago
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<title>CR16 Operand Qualifiers - Using as</title>
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<!--
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This file documents the GNU Assembler "as".
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Copyright (C) 1991-2015 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="CR16-Operand-Qualifiers"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="CR16-Syntax.html#CR16-Syntax">CR16 Syntax</a>,
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Up: <a rel="up" accesskey="u" href="CR16_002dDependent.html#CR16_002dDependent">CR16-Dependent</a>
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<hr>
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</div>
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<h4 class="subsection">9.7.1 CR16 Operand Qualifiers</h4>
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<p><a name="index-CR16-Operand-Qualifiers-818"></a>
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The National Semiconductor CR16 target of <code>as</code> has a few machine dependent operand qualifiers.
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<p>Operand expression type qualifier is an optional field in the instruction operand, to determines the type of the expression field of an operand. The <code>@</code> is required. CR16 architecture uses one of the following expression qualifiers:
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<dl>
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<dt><code>s</code><dd>- <code>Specifies expression operand type as small</code>
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<br><dt><code>m</code><dd>- <code>Specifies expression operand type as medium</code>
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<br><dt><code>l</code><dd>- <code>Specifies expression operand type as large</code>
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<br><dt><code>c</code><dd>- <code>Specifies the CR16 Assembler generates a relocation entry for the operand, where pc has implied bit, the expression is adjusted accordingly. The linker uses the relocation entry to update the operand address at link time.</code>
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<br><dt><code>got/GOT</code><dd>- <code>Specifies the CR16 Assembler generates a relocation entry for the operand, offset from Global Offset Table. The linker uses this relocation entry to update the operand address at link time</code>
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<br><dt><code>cgot/cGOT</code><dd>- <code>Specifies the CompactRISC Assembler generates a relocation entry for the operand, where pc has implied bit, the expression is adjusted accordingly. The linker uses the relocation entry to update the operand address at link time.</code>
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</dl>
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<p>CR16 target operand qualifiers and its size (in bits):
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<dl>
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<dt>‘<samp><span class="samp">Immediate Operand: s</span></samp>’<dd>4 bits.
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<br><dt>‘<samp><span class="samp">Immediate Operand: m</span></samp>’<dd>16 bits, for movb and movw instructions.
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<br><dt>‘<samp><span class="samp">Immediate Operand: m</span></samp>’<dd>20 bits, movd instructions.
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<br><dt>‘<samp><span class="samp">Immediate Operand: l</span></samp>’<dd>32 bits.
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<br><dt>‘<samp><span class="samp">Absolute Operand: s</span></samp>’<dd>Illegal specifier for this operand.
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<br><dt>‘<samp><span class="samp">Absolute Operand: m</span></samp>’<dd>20 bits, movd instructions.
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<br><dt>‘<samp><span class="samp">Displacement Operand: s</span></samp>’<dd>8 bits.
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<br><dt>‘<samp><span class="samp">Displacement Operand: m</span></samp>’<dd>16 bits.
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<br><dt>‘<samp><span class="samp">Displacement Operand: l</span></samp>’<dd>24 bits.
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</dl>
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<p>For example:
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<pre class="example"> 1 <code>movw $_myfun@c,r1</code>
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This loads the address of _myfun, shifted right by 1, into r1.
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2 <code>movd $_myfun@c,(r2,r1)</code>
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This loads the address of _myfun, shifted right by 1, into register-pair r2-r1.
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3 <code>_myfun_ptr:</code>
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<code>.long _myfun@c</code>
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<code>loadd _myfun_ptr, (r1,r0)</code>
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<code>jal (r1,r0)</code>
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This .long directive, the address of _myfunc, shifted right by 1 at link time.
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4 <code>loadd _data1@GOT(r12), (r1,r0)</code>
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This loads the address of _data1, into global offset table (ie GOT) and its offset value from GOT loads into register-pair r2-r1.
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5 <code>loadd _myfunc@cGOT(r12), (r1,r0)</code>
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This loads the address of _myfun, shifted right by 1, into global offset table (ie GOT) and its offset value from GOT loads into register-pair r1-r0.
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</pre>
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</body></html>
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