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<a name="Disassembly-In-Guile"></a>
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<a name="Disassembly-In-Guile-1"></a>
<h4 class="subsubsection">23.3.3.22 Disassembly In Guile</h4>

<p>The disassembler can be invoked from Scheme code.
Furthermore, the disassembler can take a Guile port as input,
allowing one to disassemble from any source, and not just target memory.
</p>
<dl>
<dt><a name="index-arch_002ddisassemble"></a>Scheme Procedure: <strong>arch-disassemble</strong> <em>arch start-pc <span class="roman">[</span>#:port port<span class="roman">]</span> <span class="roman">[</span>#:offset offset<span class="roman">]</span> <span class="roman">[</span>#:size size<span class="roman">]</span> <span class="roman">[</span>#:count count<span class="roman">]</span></em></dt>
<dd><p>Return a list of disassembled instructions starting from the memory
address <var>start-pc</var>.
</p>
<p>The optional argument <var>port</var> specifies the input port to read bytes from.
If <var>port</var> is <code>#f</code> then bytes are read from target memory.
</p>
<p>The optional argument <var>offset</var> specifies the address offset of the
first byte in <var>port</var>.  This is useful, for example, when <var>port</var>
specifies a &lsquo;<samp>bytevector</samp>&rsquo; and you want the bytevector to be disassembled
as if it came from that address.  The <var>start-pc</var> passed to the reader
for <var>port</var> is offset by the same amount.
</p>
<p>Example:
</p><div class="smallexample">
<pre class="smallexample">(gdb) guile (use-modules (rnrs io ports))
(gdb) guile (define pc (value-&gt;integer (parse-and-eval &quot;$pc&quot;)))
(gdb) guile (define mem (open-memory #:start pc))
(gdb) guile (define bv (get-bytevector-n mem 10))
(gdb) guile (define bv-port (open-bytevector-input-port bv))
(gdb) guile (define arch (current-arch))
(gdb) guile (arch-disassemble arch pc #:port bv-port #:offset pc)
(((address . 4195516) (asm . &quot;mov    $0x4005c8,%edi&quot;) (length . 5)))
</pre></div>

<p>The optional arguments <var>size</var> and
<var>count</var> determine the number of instructions in the returned list.
If either <var>size</var> or <var>count</var> is specified as zero, then
no instructions are disassembled and an empty list is returned.
If both the optional arguments <var>size</var> and <var>count</var> are
specified, then a list of at most <var>count</var> disassembled instructions
whose start address falls in the closed memory address interval from
<var>start-pc</var> to (<var>start-pc</var> + <var>size</var> - 1) are returned.
If <var>size</var> is not specified, but <var>count</var> is specified,
then <var>count</var> number of instructions starting from the address
<var>start-pc</var> are returned.  If <var>count</var> is not specified but
<var>size</var> is specified, then all instructions whose start address
falls in the closed memory address interval from <var>start-pc</var> to
(<var>start-pc</var> + <var>size</var> - 1) are returned.
If neither <var>size</var> nor <var>count</var> are specified, then a single
instruction at <var>start-pc</var> is returned.
</p>
<p>Each element of the returned list is an alist (associative list)
with the following keys:
</p>
<dl compact="compact">
<dt><code>address</code></dt>
<dd><p>The value corresponding to this key is a Guile integer of
the memory address of the instruction.
</p>
</dd>
<dt><code>asm</code></dt>
<dd><p>The value corresponding to this key is a string value which represents
the instruction with assembly language mnemonics.  The assembly
language flavor used is the same as that specified by the current CLI
variable <code>disassembly-flavor</code>.  See <a href="Machine-Code.html#Machine-Code">Machine Code</a>.
</p>
</dd>
<dt><code>length</code></dt>
<dd><p>The value corresponding to this key is the length of the instruction in bytes.
</p>
</dd>
</dl>
</dd></dl>

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