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Up: <a rel="up" accesskey="u" href="M68HC11_002dopcodes.html#M68HC11_002dopcodes">M68HC11-opcodes</a>
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<h5 class="subsubsection">9.24.6.1 Branch Improvement</h5>
<p><a name="index-pseudo_002dopcodes_002c-M68HC11-1444"></a><a name="index-M68HC11-pseudo_002dopcodes-1445"></a><a name="index-branch-improvement_002c-M68HC11-1446"></a><a name="index-M68HC11-branch-improvement-1447"></a>
Certain pseudo opcodes are permitted for branch instructions.
They expand to the shortest branch instruction that reach the
target. Generally these mnemonics are made by prepending ‘<samp><span class="samp">j</span></samp>’ to
the start of Motorola mnemonic. These pseudo opcodes are not affected
by the ‘<samp><span class="samp">--short-branches</span></samp>’ or ‘<samp><span class="samp">--force-long-branches</span></samp>’ options.
<p>The following table summarizes the pseudo-operations.
<pre class="smallexample"> Displacement Width
+-------------------------------------------------------------+
| Options |
| --short-branches --force-long-branches |
+--------------------------+----------------------------------+
Op |BYTE WORD | BYTE WORD |
+--------------------------+----------------------------------+
bsr | bsr <pc-rel> <error> | jsr <abs> |
bra | bra <pc-rel> <error> | jmp <abs> |
jbsr | bsr <pc-rel> jsr <abs> | bsr <pc-rel> jsr <abs> |
jbra | bra <pc-rel> jmp <abs> | bra <pc-rel> jmp <abs> |
bXX | bXX <pc-rel> <error> | bNX +3; jmp <abs> |
jbXX | bXX <pc-rel> bNX +3; | bXX <pc-rel> bNX +3; jmp <abs> |
| jmp <abs> | |
+--------------------------+----------------------------------+
XX: condition
NX: negative of condition XX
</pre>
<dl>
<dt><code>jbsr</code><dt><code>jbra</code><dd>These are the simplest jump pseudo-operations; they always map to one
particular machine instruction, depending on the displacement to the
branch target.
<br><dt><code>jb</code><var>XX</var><dd>Here, ‘<samp><span class="samp">jb</span><var>XX</var></samp>’ stands for an entire family of pseudo-operations,
where <var>XX</var> is a conditional branch or condition-code test. The full
list of pseudo-ops in this family is:
<pre class="smallexample"> jbcc jbeq jbge jbgt jbhi jbvs jbpl jblo
jbcs jbne jblt jble jbls jbvc jbmi
</pre>
<p>For the cases of non-PC relative displacements and long displacements,
<code>as</code> issues a longer code fragment in terms of
<var>NX</var>, the opposite condition to <var>XX</var>. For example, for the
non-PC relative case:
<pre class="smallexample"> jb<var>XX</var> foo
</pre>
<p>gives
<pre class="smallexample"> b<var>NX</var>s oof
jmp foo
oof:
</pre>
</dl>
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