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176 lines
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<title>V850 Opcodes - Using as</title>
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<!--
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This file documents the GNU Assembler "as".
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Copyright (C) 1991-2019 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="V850-Opcodes"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="V850-Directives.html#V850-Directives">V850 Directives</a>,
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Up: <a rel="up" accesskey="u" href="V850_002dDependent.html#V850_002dDependent">V850-Dependent</a>
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<hr>
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</div>
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<h4 class="subsection">9.49.5 Opcodes</h4>
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<p><a name="index-V850-opcodes-2465"></a><a name="index-opcodes-for-V850-2466"></a><code>as</code> implements all the standard V850 opcodes.
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<p><code>as</code> also implements the following pseudo ops:
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<a name="index-g_t_0040code_007bhi0_007d-pseudo_002dop_002c-V850-2467"></a>
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<dl><dt><code>hi0()</code><dd>Computes the higher 16 bits of the given expression and stores it into
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the immediate operand field of the given instruction. For example:
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<p>‘<samp><span class="samp">mulhi hi0(here - there), r5, r6</span></samp>’
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<p>computes the difference between the address of labels 'here' and
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'there', takes the upper 16 bits of this difference, shifts it down 16
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bits and then multiplies it by the lower 16 bits in register 5, putting
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the result into register 6.
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<p><a name="index-g_t_0040code_007blo_007d-pseudo_002dop_002c-V850-2468"></a><br><dt><code>lo()</code><dd>Computes the lower 16 bits of the given expression and stores it into
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the immediate operand field of the given instruction. For example:
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<p>‘<samp><span class="samp">addi lo(here - there), r5, r6</span></samp>’
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<p>computes the difference between the address of labels 'here' and
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'there', takes the lower 16 bits of this difference and adds it to
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register 5, putting the result into register 6.
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<p><a name="index-g_t_0040code_007bhi_007d-pseudo_002dop_002c-V850-2469"></a><br><dt><code>hi()</code><dd>Computes the higher 16 bits of the given expression and then adds the
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value of the most significant bit of the lower 16 bits of the expression
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and stores the result into the immediate operand field of the given
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instruction. For example the following code can be used to compute the
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address of the label 'here' and store it into register 6:
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<p>‘<samp><span class="samp">movhi hi(here), r0, r6</span></samp>’
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‘<samp><span class="samp">movea lo(here), r6, r6</span></samp>’
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<p>The reason for this special behaviour is that movea performs a sign
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extension on its immediate operand. So for example if the address of
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'here' was 0xFFFFFFFF then without the special behaviour of the hi()
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pseudo-op the movhi instruction would put 0xFFFF0000 into r6, then the
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movea instruction would takes its immediate operand, 0xFFFF, sign extend
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it to 32 bits, 0xFFFFFFFF, and then add it into r6 giving 0xFFFEFFFF
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which is wrong (the fifth nibble is E). With the hi() pseudo op adding
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in the top bit of the lo() pseudo op, the movhi instruction actually
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stores 0 into r6 (0xFFFF + 1 = 0x0000), so that the movea instruction
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stores 0xFFFFFFFF into r6 - the right value.
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<p><a name="index-g_t_0040code_007bhilo_007d-pseudo_002dop_002c-V850-2470"></a><br><dt><code>hilo()</code><dd>Computes the 32 bit value of the given expression and stores it into
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the immediate operand field of the given instruction (which must be a
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mov instruction). For example:
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<p>‘<samp><span class="samp">mov hilo(here), r6</span></samp>’
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<p>computes the absolute address of label 'here' and puts the result into
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register 6.
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<p><a name="index-g_t_0040code_007bsdaoff_007d-pseudo_002dop_002c-V850-2471"></a><br><dt><code>sdaoff()</code><dd>Computes the offset of the named variable from the start of the Small
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Data Area (whose address is held in register 4, the GP register) and
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stores the result as a 16 bit signed value in the immediate operand
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field of the given instruction. For example:
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<p>‘<samp><span class="samp">ld.w sdaoff(_a_variable)[gp],r6</span></samp>’
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<p>loads the contents of the location pointed to by the label '_a_variable'
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into register 6, provided that the label is located somewhere within +/-
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32K of the address held in the GP register. [Note the linker assumes
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that the GP register contains a fixed address set to the address of the
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label called '__gp'. This can either be set up automatically by the
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linker, or specifically set by using the ‘<samp><span class="samp">--defsym __gp=<value></span></samp>’
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command-line option].
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<p><a name="index-g_t_0040code_007btdaoff_007d-pseudo_002dop_002c-V850-2472"></a><br><dt><code>tdaoff()</code><dd>Computes the offset of the named variable from the start of the Tiny
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Data Area (whose address is held in register 30, the EP register) and
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stores the result as a 4,5, 7 or 8 bit unsigned value in the immediate
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operand field of the given instruction. For example:
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<p>‘<samp><span class="samp">sld.w tdaoff(_a_variable)[ep],r6</span></samp>’
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<p>loads the contents of the location pointed to by the label '_a_variable'
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into register 6, provided that the label is located somewhere within +256
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bytes of the address held in the EP register. [Note the linker assumes
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that the EP register contains a fixed address set to the address of the
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label called '__ep'. This can either be set up automatically by the
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linker, or specifically set by using the ‘<samp><span class="samp">--defsym __ep=<value></span></samp>’
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command-line option].
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<p><a name="index-g_t_0040code_007bzdaoff_007d-pseudo_002dop_002c-V850-2473"></a><br><dt><code>zdaoff()</code><dd>Computes the offset of the named variable from address 0 and stores the
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result as a 16 bit signed value in the immediate operand field of the
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given instruction. For example:
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<p>‘<samp><span class="samp">movea zdaoff(_a_variable),zero,r6</span></samp>’
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<p>puts the address of the label '_a_variable' into register 6, assuming
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that the label is somewhere within the first 32K of memory. (Strictly
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speaking it also possible to access the last 32K of memory as well, as
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the offsets are signed).
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<p><a name="index-g_t_0040code_007bctoff_007d-pseudo_002dop_002c-V850-2474"></a><br><dt><code>ctoff()</code><dd>Computes the offset of the named variable from the start of the Call
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Table Area (whose address is held in system register 20, the CTBP
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register) and stores the result a 6 or 16 bit unsigned value in the
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immediate field of then given instruction or piece of data. For
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example:
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<p>‘<samp><span class="samp">callt ctoff(table_func1)</span></samp>’
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<p>will put the call the function whose address is held in the call table
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at the location labeled 'table_func1'.
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<p><a name="index-g_t_0040code_007blongcall_007d-pseudo_002dop_002c-V850-2475"></a><br><dt><code>.longcall name</code><dd>Indicates that the following sequence of instructions is a long call
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to function <code>name</code>. The linker will attempt to shorten this call
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sequence if <code>name</code> is within a 22bit offset of the call. Only
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valid if the <code>-mrelax</code> command-line switch has been enabled.
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<p><a name="index-g_t_0040code_007blongjump_007d-pseudo_002dop_002c-V850-2476"></a><br><dt><code>.longjump name</code><dd>Indicates that the following sequence of instructions is a long jump
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to label <code>name</code>. The linker will attempt to shorten this code
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sequence if <code>name</code> is within a 22bit offset of the jump. Only
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valid if the <code>-mrelax</code> command-line switch has been enabled.
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</dl>
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<p>For information on the V850 instruction set, see <cite>V850
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Family 32-/16-Bit single-Chip Microcontroller Architecture Manual</cite> from NEC.
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Ltd.
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<!-- Copyright (C) 1991-2019 Free Software Foundation, Inc. -->
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<!-- This is part of the GAS manual. -->
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<!-- For copying conditions, see the file as.texinfo. -->
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<!-- VAX/VMS description enhanced and corrected by Klaus K"aempf, kkaempf@progis.de -->
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</body></html>
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