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<h5 class="subsubsection">23.3.3.22 Disassembly In Guile</h5>

<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.

<!-- TODO: line length -->
<div class="defun">
&mdash; Scheme Procedure: <b>arch-disassemble</b><var> arch start-pc </var><span class="roman">[</span><var>#:port port</var><span class="roman">]</span> <span class="roman">[</span><var>#:offset offset</var><span class="roman">]</span> <span class="roman">[</span><var>#:size size</var><span class="roman">]</span> <span class="roman">[</span><var>#:count count</var><span class="roman">]</span><var><a name="index-arch_002ddisassemble-2843"></a></var><br>
<blockquote><p>Return a list of disassembled instructions starting from the memory
address <var>start-pc</var>.

        <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>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><span class="samp">bytevector</span></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>Example:
     <pre class="smallexample">          (gdb) guile (use-modules (rnrs io ports))
          (gdb) guile (define pc (value-&gt;integer (parse-and-eval "$pc")))
          (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 . "mov    $0x4005c8,%edi") (length . 5)))
</pre>
        <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>Each element of the returned list is an alist (associative list)
with the following keys:

          <dl>
<dt><code>address</code><dd>The value corresponding to this key is a Guile integer of
the memory address of the instruction.

          <br><dt><code>asm</code><dd>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>.

          <br><dt><code>length</code><dd>The value corresponding to this key is the length of the instruction in bytes.

        </dl>
        </p></blockquote></div>

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