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<h1 id="cmpt-295-unit---machine-level-programming">CMPT 295 Unit - Machine-Level Programming</h1>
<p>Lecture 10 – Assembly language basics: leaq instruction,
memory addressing modes and
arithmetic &amp; logical operations</p>
<h2 id="last-lecture">Last Lecture</h2>
<ul>
<li>As x86-64 assembly s/w dev., we now get to see more of the microprocessor
(CPU) state: PC, registers, condition codes</li>
<li>x86-64 assembly language – Data
<ul>
<li>16 integer registers of 1, 2, 4 or 8 bytes + memory address of 8 bytes</li>
<li>Floating point registers of 4 or 8 bytes</li>
<li>No aggregate types such as arrays or structures</li>
</ul>
</li>
<li>x86-64 assembly language – Instructions
<ul>
<li>mov* instruction family
<ul>
<li>From register to register</li>
<li>From memory to register</li>
<li>From register to memory</li>
</ul>
</li>
<li>Memory addressing modes</li>
<li>Cannot do memory-memory transfer with a single mov* instruction</li>
</ul>
</li>
</ul>
<h2 id="why-cannot-do-memory-memory-transfer-with-a-single-mov-instruction">Why cannot do memory-memory transfer with a single mov* instruction?</h2>
<ul>
<li>No x86-64 assembly instructions that take 2 memory addresses as
operands</li>
<li>Such instruction would
<ul>
<li>Makes for very long machine instructions</li>
<li>Require more complex decoder unit (on microprocessor)
in other words, require more complex microprocessor datapath</li>
<li>Memory only has one data bus and one address bus</li>
<li>No appetite for instruction set architects to create such instructions</li>
<li>Registers very fast and can easily be used for such transfer</li>
</ul>
</li>
<li>More info here: https://stackoverflow.com/questions/33794169/why-isnt-movl-frommemory-to-memory-allowed</li>
</ul>
<h2 id="last-lecture-1">Last Lecture</h2>
<p>Requirement: When reading/writing assembly code…</p>
<ul>
<li>add a comment at the top of your function in your assembly code describing the parameter-toregister mapping</li>
<li>Comment each of your assembly language instruction by explaining what it does using corresponding C statement or pseudocode</li>
</ul>
<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>swap:
# xp -&gt; %rdi, yp -&gt; %rsi
movq (%rdi), %rax # L1 = *xp
movq (%rsi), %rdx # L2 = *yp
movq %rdx, (%rdi) # *xp = L2
movq %rax, (%rsi) # *yp = L1
ret
</code></pre></div></div>
<h2 id="todays-menu">Today’s Menu</h2>
<ul>
<li>Introduction
<ul>
<li>C program -&gt; assembly code -&gt; machine level code</li>
</ul>
</li>
<li>Assembly language basics: data, move operation
<ul>
<li>(highlighted) Memory addressing modes</li>
</ul>
</li>
<li>(highlighted) Operation leaq and Arithmetic &amp; logical operations</li>
<li>Conditional Statement – Condition Code + cmov*</li>
<li>Loops</li>
<li>Function call – Stack</li>
<li>Array</li>
<li>Buffer Overflow</li>
<li>Floating-point operations</li>
</ul>
<h2 id="various-types-of-operands-to-x86-64-instructions">Various types of operands to x86-64 instructions</h2>
<ol>
<li>Integer value as operand directly in an instruction
<ul>
<li>This operand is called immediate</li>
<li>Operand syntax: Imm</li>
<li>Examples: <code class="language-plaintext highlighter-rouge">movq $0x4,%rax</code> and <code class="language-plaintext highlighter-rouge">movb $-17,%al</code> (NOTE: These instructions copy immediate value to register)</li>
</ul>
</li>
<li>Registers as operands in an instruction
(Note: So far, this is the type of operands what we have seen!)
<ul>
<li>Operand value: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>a</mi></msub><mo stretchy="false">]</mo></mrow><annotation encoding="application/x-tex">R[r_{a}]</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.151392em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">a</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span></span></span></span></li>
<li>Operand syntax: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi mathvariant="normal">%</mi><msub><mi>r</mi><mi>a</mi></msub></mrow><annotation encoding="application/x-tex">\%r_{a}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.9em;vertical-align:-0.15em;"></span><span class="mord">%</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.151392em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">a</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span> &lt;- name of particular register</li>
<li>Example: <code class="language-plaintext highlighter-rouge">movq %rax,%rdx</code> (NOTE: This instruction copies the value of one register into another register)</li>
</ul>
</li>
<li>Memory address – using various memory addressing
modes as operands in an instruction</li>
</ol>
<h2 id="memory-addressing-modes">Memory addressing modes</h2>
<p>We access memory in an x86-64 instruction by expressing a memory address through various memory addressing modes</p>
<ol>
<li>Absolute memory addressing mode
<ul>
<li>Use memory address as operand directly in instruction</li>
</ul>
<ul>
<li>The operand is also called immediate
* Operand syntax: Imm
* Effect: M[Imm]
* Example: call plus (NOTE: plus refers to the memory address of the first byte of the first instruction of the function called plus (see Demo))</li>
</ul>
</li>
<li>Indirect memory addressing mode</li>
</ol>
<h2 id="2-indirect-memory-addressing-mode">2. Indirect memory addressing mode</h2>
<ul>
<li>When a register contains an address
<ul>
<li>Similar to a pointer in C</li>
</ul>
</li>
<li>To access the data at the address contained in the
register, we use parentheses (…)</li>
<li>General Syntax: (<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>)</li>
<li>Effect: M[R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>]]</li>
</ul>
<h2 id="2-indirect-memory-addressing-mode-1">2. Indirect memory addressing mode</h2>
<h3 id="example-register-to-register">Example: register to register</h3>
<p>Assembly code: <code class="language-plaintext highlighter-rouge">movq %rdx, %rax</code></p>
<p>Meaning, or affect: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>rax</mtext><mo>←</mo><mtext>rdx</mtext></mrow><annotation encoding="application/x-tex">\text{rax} \leftarrow \text{rdx}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.43056em;vertical-align:0em;"></span><span class="mord text"><span class="mord">rax</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">←</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.69444em;vertical-align:0em;"></span><span class="mord text"><span class="mord">rdx</span></span></span></span></span>, or <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>R[rax]</mtext><mo>←</mo><mtext>R[rdx]</mtext></mrow><annotation encoding="application/x-tex">\text{R[rax]} \leftarrow \text{R[rdx]}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">R[rax]</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">←</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">R[rdx]</span></span></span></span></span></p>
<table>
<thead>
<tr>
<th>Register</th>
<th>Before</th>
<th>After</th>
</tr>
</thead>
<tbody>
<tr>
<td>%rax</td>
<td>15</td>
<td>6</td>
</tr>
<tr>
<td>%rdx</td>
<td>6</td>
<td>6</td>
</tr>
<tr>
<td>M[6]</td>
<td>11</td>
<td>11</td>
</tr>
</tbody>
</table>
<h3 id="vs-memory-to-register">vs. memory to register</h3>
<p>Assembly code: <code class="language-plaintext highlighter-rouge">movq (%rdx),%rax</code></p>
<p>Meaning or affect: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>rax</mtext><mo>←</mo><mtext>M[rdx]</mtext></mrow><annotation encoding="application/x-tex">\text{rax} \leftarrow \text{M[rdx]}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.43056em;vertical-align:0em;"></span><span class="mord text"><span class="mord">rax</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">←</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">M[rdx]</span></span></span></span></span> or <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>R[rax]</mtext><mo>←</mo><mtext>M[R[rdx]]</mtext></mrow><annotation encoding="application/x-tex">\text{R[rax]} \leftarrow \text{M[R[rdx]]}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">R[rax]</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">←</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">M[R[rdx]]</span></span></span></span></span></p>
<table>
<thead>
<tr>
<th>Register</th>
<th>Before</th>
<th>After</th>
</tr>
</thead>
<tbody>
<tr>
<td>%rax</td>
<td>15</td>
<td>11</td>
</tr>
<tr>
<td>%rdx</td>
<td>6</td>
<td>6</td>
</tr>
<tr>
<td>M[6]</td>
<td>11</td>
<td>11</td>
</tr>
</tbody>
</table>
<p>Other examples:</p>
<ul>
<li>register to memory: <code class="language-plaintext highlighter-rouge">movq %rax,(%rdx)</code></li>
<li>immediate to memory: <code class="language-plaintext highlighter-rouge">movq $-147,(%rax)</code></li>
</ul>
<h2 id="leaq---load-effective-address-instruction">leaq - Load effective address instruction</h2>
<p>leaq has the form of an instruction that reads from memory to a register (because of the parentheses), however it <strong><em>does not</em></strong> reference memory at all!</p>
<ul>
<li>Often used for address computations and general arithmetic computations</li>
<li>Syntax: <code class="language-plaintext highlighter-rouge">leaq Source, Destination</code></li>
<li>Example:
<ol>
<li>Computing addresses
<ul>
<li>if %rax &lt;- 0x0000000000000008 and %rcx &lt;- 16</li>
<li><code class="language-plaintext highlighter-rouge">leaq (%rax, %rcx), %rdx</code></li>
<li>Once executed, rdx will contain 0x18</li>
</ul>
</li>
<li>Computing arithmetic expressions of the form <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>x</mi><mo>+</mo><mi>k</mi><mo>×</mo><mi>y</mi></mrow><annotation encoding="application/x-tex">x + k \times y</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.66666em;vertical-align:-0.08333em;"></span><span class="mord mathnormal">x</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.77777em;vertical-align:-0.08333em;"></span><span class="mord mathnormal" style="margin-right:0.03148em;">k</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.625em;vertical-align:-0.19444em;"></span><span class="mord mathnormal" style="margin-right:0.03588em;">y</span></span></span></span> where <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>k</mi><mo>∈</mo><mo stretchy="false">[</mo><mn>1</mn><mo separator="true">,</mo><mn>2</mn><mo separator="true">,</mo><mn>4</mn><mo separator="true">,</mo><mn>8</mn><mo stretchy="false">]</mo></mrow><annotation encoding="application/x-tex">k \in [1,2,4,8]</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.73354em;vertical-align:-0.0391em;"></span><span class="mord mathnormal" style="margin-right:0.03148em;">k</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">∈</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mopen">[</span><span class="mord">1</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord">2</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord">4</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord">8</span><span class="mclose">]</span></span></span></span>
<ul>
<li>if %rdi &lt;- variable a</li>
<li><code class="language-plaintext highlighter-rouge">leaq (%rdi, %rdi, 2), %rax</code> (%rdi is x, 2nd %rdi is y and 2 is k)</li>
<li>Once executed, rax will contain 3a</li>
<li>C code: <code class="language-plaintext highlighter-rouge">return a*3;</code></li>
</ul>
</li>
</ol>
</li>
<li>Operand Destination is a register</li>
<li>Operand Source is a memory addressing mode expression</li>
</ul>
<h2 id="3-base--displacement-memory-addressing-mode">3. “Base + displacement” memory addressing mode</h2>
<ul>
<li>General Syntax: Imm(<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>)</li>
<li>Effect: M[Imm + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>]]</li>
<li>Examples:
<ul>
<li><code class="language-plaintext highlighter-rouge">movq %rax, -8(%rsp)</code></li>
<li><code class="language-plaintext highlighter-rouge">leaq 7(%rdi), %rax</code></li>
</ul>
</li>
<li>Careful here!
<ul>
<li>When dealing with <code class="language-plaintext highlighter-rouge">leaq</code>, the effect is Imm + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] <strong><em>not</em></strong> M[Imm + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>]]</li>
</ul>
</li>
</ul>
<h2 id="4-indexed-memory-addressing-mode">4. Indexed memory addressing mode</h2>
<ol>
<li>General Syntax: (<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>,<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>)
<ul>
<li>Effect: M[R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>]]</li>
<li>Example: <code class="language-plaintext highlighter-rouge">movb (%rdi, %rcx), %al</code></li>
</ul>
</li>
<li>General Syntax: Imm(rb,ri)
<ul>
<li>Effect: M[Imm + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>]]</li>
<li>Example: <code class="language-plaintext highlighter-rouge">movw 0xA(%rdi, %rcx), %r11w</code></li>
<li>Careful here! When dealing with <code class="language-plaintext highlighter-rouge">leaq</code>, the effect is</li>
</ul>
</li>
<li>R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] <strong><em>not</em></strong> M[R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></s
<li>Imm + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] <strong><em>not</em></strong> M[Imm + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>b</mi></msub></mrow><annotation encoding="application/x-tex">r_b</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>] + R[<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></spa
</ol>
<h2 id="5-scaled-indexed-memory-addressing-mode">5. Scaled indexed memory addressing mode</h2>
<ol>
<li>General Syntax: (,<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>,s)
<ul>
<li>Effect: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>M</mi><mo stretchy="false">[</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>i</mi></msub><mo stretchy="false">]</mo><mo>×</mo><mi>s</mi><mo stretchy="false">]</mo></mrow><annotation encoding="application/x-tex">M[R[r_i] \times s]</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">[</span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">s</span><span class="mclose">]</span></span></span></span></li>
<li>Example: <code class="language-plaintext highlighter-rouge">(, %rdi, 2)</code></li>
</ul>
</li>
<li>General Syntax: Imm(,<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>r</mi><mi>i</mi></msub></mrow><annotation encoding="application/x-tex">r_i</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.58056em;vertical-align:-0.15em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span></span></span></span>,s)
<ul>
<li>Effect: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>M</mi><mo stretchy="false">[</mo><mtext>Imm</mtext><mo>+</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>i</mi></msub><mo stretchy="false">]</mo><mo>×</mo><mi>s</mi><mo stretchy="false">]</mo></mrow><annotation encoding="application/x-tex">M[\text{Imm} + R[r_i] \times s]</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">[</span><span class="mord text"><span class="mord">Imm</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">s</span><span class="mclose">]</span></span></span></span></li>
<li>Example: <code class="language-plaintext highlighter-rouge">3(, %rcx, 8)</code></li>
</ul>
</li>
<li>General Syntax: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mo stretchy="false">(</mo><msub><mi>r</mi><mi>b</mi></msub><mo separator="true">,</mo><msub><mi>r</mi><mi>i</mi></msub><mo separator="true">,</mo><mi>s</mi><mo stretchy="false">)</mo></mrow><annotation encoding="application/x-tex">(r_{b},r_{i},s)</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mopen">(</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">b</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">i</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord mathnormal">s</span><span class="mclose">)</span></span></span></span>
<ul>
<li>Effect: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>M</mi><mo stretchy="false">[</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>b</mi></msub><mo stretchy="false">]</mo><mo>+</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>i</mi></msub><mo stretchy="false">]</mo><mo>×</mo><mi>s</mi><mo stretchy="false">]</mo></mrow><annotation encoding="application/x-tex">M[R[r_b] + R[r_i] \times s]</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">[</span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">s</span><span class="mclose">]</span></span></span></span></li>
<li>Example: <code class="language-plaintext highlighter-rouge">(%rdi, %rsi, 4)</code></li>
</ul>
</li>
<li>General Syntax: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Imm</mtext><mo stretchy="false">(</mo><msub><mi>r</mi><mi>b</mi></msub><mo separator="true">,</mo><msub><mi>r</mi><mi>i</mi></msub><mo separator="true">,</mo><mi>s</mi><mo stretchy="false">)</mo></mrow><annotation encoding="application/x-tex">\text{Imm}(r_{b},r_{i},s)</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">Imm</span></span><span class="mopen">(</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">b</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">i</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord mathnormal">s</span><span class="mclose">)</span></span></span></span>
<ul>
<li>Effect: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>M</mi><mo stretchy="false">[</mo><mtext>Imm</mtext><mo>+</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>b</mi></msub><mo stretchy="false">]</mo><mo>+</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>i</mi></msub><mo stretchy="false">]</mo><mo>×</mo><mi>s</mi><mo stretchy="false">]</mo></mrow><annotation encoding="application/x-tex">M[\text{Imm} + R[r_b] + R[r_i] \times s]</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">[</span><span class="mord text"><span class="mord">Imm</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">s</span><span class="mclose">]</span></span></span></span></li>
<li>Example: <code class="language-plaintext highlighter-rouge">8(%rdi, %rsi, 4)</code>
13</li>
</ul>
</li>
</ol>
<p>Again, careful here! When dealing with <code class="language-plaintext highlighter-rouge">leaq</code>, the effect is <strong><em>not</em></strong> to reference memory at all!</p>
<h2 id="summary---memory-addressing-modes">Summary - Memory addressing modes</h2>
<p>We access memory in an x86-64 instruction by expressing a
memory address through various memory addressing modes</p>
<ol>
<li>Absolute</li>
<li>Indirect</li>
<li>“Base + displacement”</li>
<li>2 indexed</li>
<li>4 scaled indexed</li>
</ol>
<p>See <a href="https://cas.sfu.ca/cas/login?service=https%3a%2f%2fwww.cs.sfu.ca%2fCourseCentral%2f295%2falavergn%2fResources%2fTable%20of%20x86-64%20Addressing%20Modes.html">Table of x86-64 Addressing Modes</a> on Resources web page of our course web site</p>
<p>Box on left of slide:</p>
<ul>
<li>General Syntax: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Imm</mtext><mo stretchy="false">(</mo><msub><mi>r</mi><mi>b</mi></msub><mo separator="true">,</mo><msub><mi>r</mi><mi>i</mi></msub><mo separator="true">,</mo><mi>s</mi><mo stretchy="false">)</mo></mrow><annotation encoding="application/x-tex">\text{Imm}(r_{b}, r_{i}, s)</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">Imm</span></span><span class="mopen">(</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">b</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">i</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord mathnormal">s</span><span class="mclose">)</span></span></span></span></li>
<li>Effect: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>M</mi><mo stretchy="false">[</mo><mtext>Imm</mtext><mo>+</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>b</mi></msub><mo stretchy="false">]</mo><mo>+</mo><mi>R</mi><mo stretchy="false">[</mo><msub><mi>r</mi><mi>i</mi></msub><mo stretchy="false">]</mo><mo>×</mo><mi>s</mi><mo stretchy="false">]</mo></mrow><annotation encoding="application/x-tex">M[\text{Imm} + R[r_b]+ R[r_i] \times s]</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">[</span><span class="mord text"><span class="mord">Imm</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">b</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.00773em;">R</span><span class="mopen">[</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">i</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">s</span><span class="mclose">]</span></span></span></span></li>
</ul>
<h2 id="lets-try-it">Let’s try it!</h2>
<table>
<thead>
<tr>
<th>Register</th>
<th>Value</th>
</tr>
</thead>
<tbody>
<tr>
<td>%rdx</td>
<td>0xf000</td>
</tr>
<tr>
<td>%rcx</td>
<td>0x0100</td>
</tr>
</tbody>
</table>
<table>
<tbody>
<tr>
<td>Expression</td>
<td>Address Computation</td>
<td>Address</td>
</tr>
<tr>
<td>8(%rdx)</td>
<td><code class="language-plaintext highlighter-rouge">0xF000</code>+<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mo stretchy="false">(</mo><msub><mn>8</mn><mn>10</mn></msub><mo>=</mo><mtext>0x8</mtext><mo stretchy="false">)</mo></mrow><annotation encoding="application/x-tex">(8_{10} = \text{0x8})</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mopen">(</span><span class="mord"><span class="mord">8</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.30110799999999993em;"><span style="top:-2.5500000000000003em;margin-left:0em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">10</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">0x8</span></span><span class="mclose">)</span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">0xF008</code></td>
</tr>
<tr>
<td>(%rdx,%rcx)</td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>0xF000</mtext><mo>=</mo><mtext>0x0100</mtext></mrow><annotation encoding="application/x-tex">\text{0xF000} = \text{0x0100}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">0xF000</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.64444em;vertical-align:0em;"></span><span class="mord text"><span class="mord">0x0100</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">0xF100</code></td>
</tr>
<tr>
<td>(%rdx,%rcx,4)</td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>0xF000</mtext><mo>+</mo><mtext>0x0100</mtext><mo>×</mo><mn>4</mn></mrow><annotation encoding="application/x-tex">\text{0xF000} + \text{0x0100} \times 4</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">0xF000</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.72777em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">0x0100</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.64444em;vertical-align:0em;"></span><span class="mord">4</span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">0xF400</code></td>
</tr>
<tr>
<td>0x80(,%rdx,2)</td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>0x80</mtext><mo>+</mo><mtext>0xF000</mtext><mo>×</mo><mn>2</mn></mrow><annotation encoding="application/x-tex">\text{0x80} + \text{0xF000} \times 2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.72777em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">0x80</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">0xF000</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.64444em;vertical-align:0em;"></span><span class="mord">2</span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">0xE080</code></td>
</tr>
<tr>
<td>0x80(%rdx, 2)</td>
<td>invalid -&gt; missing a “,” (comma) before <code class="language-plaintext highlighter-rouge">%rdx</code></td>
<td> </td>
</tr>
<tr>
<td>0x80(,%rdx, 3)</td>
<td>invalid scalar value</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="two-operand-arithmetic-instructions">Two-Operand Arithmetic Instructions</h2>
<p>* -&gt; Size designator</p>
<ul>
<li>q -&gt; long/64</li>
<li>l -&gt; int/32</li>
<li>w -&gt; short/16</li>
<li>b -&gt; char/8</li>
</ul>
<table>
<tbody>
<tr>
<td>Syntax</td>
<td>Meaning</td>
<td>Examples</td>
<td>in C</td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">add* Src, Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>+</mo><mtext>Src</mtext></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest} + \text{Src}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Src</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">addq %rax,%rcx</code></td>
<td><code class="language-plaintext highlighter-rouge">x+=y</code></td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">sub* Src, Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>−</mo><mtext>Src</mtext></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest} - \text{Src}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">−</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Src</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">subq %rax,%rcx</code></td>
<td>x-=y</td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">imul* Src, Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>×</mo><mtext>Src</mtext></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest} \times \text{Src}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">×</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Src</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">imulq $16,(%rax,%rdx,8)</code></td>
<td>x*=y</td>
</tr>
</tbody>
</table>
<ul>
<li>“destination” and “first operand” are the same
<ul>
<li>“2 operand” assembly language (machine)</li>
</ul>
</li>
<li><code class="language-plaintext highlighter-rouge">mem = mem OP mem</code> usually not supported</li>
<li>2 assembly code formats: ATT and Intel format (see Aside in Section 3.2 P. 177)
<ul>
<li>We are using the ATT format</li>
<li>Both order the operands of their instructions differently - Watch out!</li>
</ul>
</li>
</ul>
<h2 id="two-operand-logical-instructions">Two-Operand Logical Instructions</h2>
<ul>
<li>* -&gt; Size designator</li>
<li>q -&gt; long/64</li>
<li>l -&gt; int/32</li>
<li>w -&gt; short/16</li>
<li>b -&gt; char/8</li>
</ul>
<p>Transcriber’s note: the operators used for the logical operation in the following table are the proper mathematical symbols, not what is written in the document.
The symbols used in the document are: &amp;, | and ^ respectively.</p>
<table>
<thead>
<tr>
<th>Syntax</th>
<th>Meaning</th>
<th>Example</th>
</tr>
</thead>
<tbody>
<tr>
<td><code class="language-plaintext highlighter-rouge">and* Src, Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>∧</mo><mtext>Src</mtext></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest} \land \text{Src}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">∧</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Src</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">andl $252645135, %edi</code></td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">or* Src, Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>∨</mo><mtext>Src</mtext></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest} \lor \text{Src}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">∨</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Src</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">org %rsi,%rdi</code></td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">xor* Src, Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>⊕</mo><mtext>Src</mtext></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest} \oplus \text{Src}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">⊕</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Src</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">xorq %rsi,%rdi</code></td>
</tr>
</tbody>
</table>
<ul>
<li>xorq special purpose:
<ul>
<li><code class="language-plaintext highlighter-rouge">xorq %rax, %rax</code>: zeroes register %rax</li>
<li><code class="language-plaintext highlighter-rouge">movq $0, %rax</code>: also zeroes register %rax</li>
</ul>
</li>
<li>x86-64 convention:
<ul>
<li>Any instruction updating the lower 4 bytes will cause the higher-order bytes to be set to 0</li>
<li><code class="language-plaintext highlighter-rouge">xorl %eax, %eax</code> and <code class="language-plaintext highlighter-rouge">movl $0, %eax</code> &lt;- also zeroes register <code class="language-plaintext highlighter-rouge">%rax</code></li>
</ul>
</li>
</ul>
<h2 id="two-operand-shift-instructions">Two-Operand Shift Instructions</h2>
<ul>
<li>* -&gt; Size designator</li>
<li>q -&gt; long/64</li>
<li>l -&gt; int/32</li>
<li>w -&gt; short/16</li>
<li>b -&gt; char/8</li>
</ul>
<table>
<tbody>
<tr>
<td>Syntax</td>
<td>Meaning</td>
<td>Example</td>
<td>Note</td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">sal* Src, Dest</code></td>
<td>Dest &lt;- Dest « Src</td>
<td><code class="language-plaintext highlighter-rouge">salq $4,%rax</code></td>
<td>Left shift–also called <code class="language-plaintext highlighter-rouge">shlq</code>: filling Dest with 0, from the right</td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">sar* Src, Dest</code></td>
<td>Dest &lt;- » Src</td>
<td><code class="language-plaintext highlighter-rouge">sarl %cl,%rax</code></td>
<td>Right arithmatic Shift: filling Dest with sign bit, form the left.</td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">shr* Src, Dest</code></td>
<td>Dest &lt;- Dest » Src</td>
<td><code class="language-plaintext highlighter-rouge">shrq $2,%r8</code></td>
<td>Right logical Shift: filling Rest with 0, from the left</td>
</tr>
</tbody>
</table>
<h2 id="one-operand-arithmetic-instructions">One-Operand Arithmetic Instructions</h2>
<ul>
<li>* -&gt; Size designator</li>
<li>q -&gt; long/64</li>
<li>l -&gt; int/32</li>
<li>w -&gt; short/16</li>
<li>b -&gt; char/8</li>
</ul>
<table>
<tbody>
<tr>
<td>Syntax</td>
<td>Meaning</td>
<td>Examples</td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">inc* Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>+</mo><mn>1</mn></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest}+1</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.64444em;vertical-align:0em;"></span><span class="mord">1</span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">incq (%rsp)</code></td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">dec* Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mtext>Dest</mtext><mo>−</mo><mn>1</mn></mrow><annotation encoding="application/x-tex">\text{Dest} = \text{Dest}-1</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2222222222222222em;"></span><span class="mbin">−</span><span class="mspace" style="margin-right:0.2222222222222222em;"></span></span><span class="base"><span class="strut" style="height:0.64444em;vertical-align:0em;"></span><span class="mord">1</span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">decq %rsi</code></td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">neg* Dest</code></td>
<td><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Dest</mtext><mo>=</mo><mo>−</mo><mtext>Dest</mtext></mrow><annotation encoding="application/x-tex">\text{Dest} = -\text{Dest}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.68333em;vertical-align:0em;"></span><span class="mord text"><span class="mord">Dest</span></span><span class="mspace" style="margin-right:0.2777777777777778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2777777777777778em;"></span></span><span class="base"><span class="strut" style="height:0.76666em;vertical-align:-0.08333em;"></span><span class="mord">−</span><span class="mord text"><span class="mord">Dest</span></span></span></span></span></td>
<td><code class="language-plaintext highlighter-rouge">negl %eax</code></td>
</tr>
<tr>
<td><code class="language-plaintext highlighter-rouge">not* Dest</code></td>
<td>Dest = ~Dest</td>
<td><code class="language-plaintext highlighter-rouge">notq %rdi</code></td>
</tr>
</tbody>
</table>
<h2 id="summary">Summary</h2>
<ul>
<li><code class="language-plaintext highlighter-rouge">leaq</code> - load effective address instruction</li>
<li>Various types of operands to x86-64 instructions
<ul>
<li>Immediate (constant integral value)</li>
<li>Register (16 registers)</li>
<li>Memory address (various memory addressing modes)
<ul>
<li>General Syntax: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mtext>Imm</mtext><mo stretchy="false">(</mo><msub><mi>r</mi><mi>b</mi></msub><mo separator="true">,</mo><msub><mi>r</mi><mi>i</mi></msub><mo separator="true">,</mo><mi>s</mi><mo stretchy="false">)</mo></mrow><annotation encoding="application/x-tex">\text{Imm}(r_{b}, r_{i}, s)</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord text"><span class="mord">Imm</span></span><span class="mopen">(</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.33610799999999996em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">b</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.31166399999999994em;"><span style="top:-2.5500000000000003em;margin-left:-0.02778em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mathnormal mtight">i</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.16666666666666666em;"></span><span class="mord mathnormal">s</span><span class="mclose">)</span></span></span></span></li>
</ul>
</li>
</ul>
</li>
<li>Arithmetic &amp; logical operations
<ul>
<li>Arithmetic instructions: <code class="language-plaintext highlighter-rouge">add*</code>, <code class="language-plaintext highlighter-rouge">sub*</code>, <code class="language-plaintext highlighter-rouge">imul*</code>, <code class="language-plaintext highlighter-rouge">inc*</code>, <code class="language-plaintext highlighter-rouge">dec*</code>, <code class="language-plaintext highlighter-rouge">neg*</code>, <code class="language-plaintext highlighter-rouge">not*</code></li>
<li>Logical instructions: <code class="language-plaintext highlighter-rouge">and*</code>, <code class="language-plaintext highlighter-rouge">or*</code>, <code class="language-plaintext highlighter-rouge">xor*</code></li>
<li>Shift instructions: <code class="language-plaintext highlighter-rouge">sal*</code>, <code class="language-plaintext highlighter-rouge">sar*</code>, <code class="language-plaintext highlighter-rouge">shr*</code></li>
</ul>
</li>
</ul>
<h2 id="next-lecture">Next lecture</h2>
<ul>
<li>Introduction
<ul>
<li>C program -&gt; assembly code -&gt; machine level code</li>
</ul>
</li>
<li>Assembly language basics: data, move operation
<ul>
<li>Memory addressing modes</li>
</ul>
</li>
<li>Operation <code class="language-plaintext highlighter-rouge">leaq</code> and Arithmetic &amp; logical operations</li>
<li>Conditional Statement – Condition Code + cmov*</li>
<li>Loops</li>
<li>Function call – Stack</li>
<li>Array</li>
<li>Buffer Overflow</li>
<li>Floating-point operations</li>
</ul>
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