mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.


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<a href='https://github.com/akkartik/mu/blob/master/021byte_addressing.cc'>https://github.com/akkartik/mu/blob/master/021byte_addressing.cc</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr">  1 </span><span class="Comment">//: SubX mostly deals with instructions operating on 32-bit operands, but we</span>
<span id="L2" class="LineNr">  2 </span><span class="Comment">//: still need to deal with raw bytes for strings and so on.</span>
<span id="L3" class="LineNr">  3 </span>
<span id="L4" class="LineNr">  4 </span><span class="Comment">//: Unfortunately the register encodings when dealing with bytes are a mess.</span>
<span id="L5" class="LineNr">  5 </span><span class="Comment">//: We need a special case for them.</span>
<span id="L6" class="LineNr">  6 </span><span class="Delimiter">:(code)</span>
<span id="L7" class="LineNr">  7 </span>string <a href='021byte_addressing.cc.html#L7'>rname_8bit</a><span class="Delimiter">(</span><span class="Normal">uint8_t</span> r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L8" class="LineNr">  8 </span>  <span class="Normal">switch</span> <span class="Delimiter">(</span>r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L9" class="LineNr">  9 </span>  <span class="Normal">case</span> <span class="Constant">0</span>: <span class="Identifier">return</span> <span class="Constant">&quot;AL&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// lowest byte of EAX</span>
<span id="L10" class="LineNr"> 10 </span>  <span class="Normal">case</span> <span class="Constant">1</span>: <span class="Identifier">return</span> <span class="Constant">&quot;CL&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// lowest byte of ECX</span>
<span id="L11" class="LineNr"> 11 </span>  <span class="Normal">case</span> <span class="Constant">2</span>: <span class="Identifier">return</span> <span class="Constant">&quot;DL&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// lowest byte of EDX</span>
<span id="L12" class="LineNr"> 12 </span>  <span class="Normal">case</span> <span class="Constant">3</span>: <span class="Identifier">return</span> <span class="Constant">&quot;BL&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// lowest byte of EBX</span>
<span id="L13" class="LineNr"> 13 </span>  <span class="Normal">case</span> <span class="Constant">4</span>: <span class="Identifier">return</span> <span class="Constant">&quot;AH&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// second lowest byte of EAX</span>
<span id="L14" class="LineNr"> 14 </span>  <span class="Normal">case</span> <span class="Constant">5</span>: <span class="Identifier">return</span> <span class="Constant">&quot;CH&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// second lowest byte of ECX</span>
<span id="L15" class="LineNr"> 15 </span>  <span class="Normal">case</span> <span class="Constant">6</span>: <span class="Identifier">return</span> <span class="Constant">&quot;DH&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// second lowest byte of EDX</span>
<span id="L16" class="LineNr"> 16 </span>  <span class="Normal">case</span> <span class="Constant">7</span>: <span class="Identifier">return</span> <span class="Constant">&quot;BH&quot;</span><span class="Delimiter">;</span>  <span class="Comment">// second lowest byte of EBX</span>
<span id="L17" class="LineNr"> 17 </span>  <span class="Normal">default</span>: <a href='003trace.cc.html#L228'>raise</a> &lt;&lt; <span class="Constant">&quot;invalid 8-bit register &quot;</span> &lt;&lt; r &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>  <span class="Identifier">return</span> <span class="Constant">&quot;&quot;</span><span class="Delimiter">;</span>
<span id="L18" class="LineNr"> 18 </span>  <span class="Delimiter">}</span>
<span id="L19" class="LineNr"> 19 </span><span class="Delimiter">}</span>
<span id="L20" class="LineNr"> 20 </span>
<span id="L21" class="LineNr"> 21 </span><span class="Normal">uint8_t</span>* <a href='021byte_addressing.cc.html#L21'>effective_byte_address</a><span class="Delimiter">(</span><span class="Normal">uint8_t</span> modrm<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L22" class="LineNr"> 22 </span>  <span class="Normal">uint8_t</span> mod = <span class="Delimiter">(</span>modrm&gt;&gt;<span class="Constant">6</span><span class="Delimiter">);</span>
<span id="L23" class="LineNr"> 23 </span>  <span class="Normal">uint8_t</span> rm = modrm &amp; <span class="Constant">0x7</span><span class="Delimiter">;</span>
<span id="L24" class="LineNr"> 24 </span>  <span class="Normal">if</span> <span class="Delimiter">(</span>mod == <span class="Constant">3</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L25" class="LineNr"> 25 </span>    <span class="Comment">// select an 8-bit register</span>
<span id="L26" class="LineNr"> 26 </span>    <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;r/m8 is &quot;</span> &lt;&lt; <a href='021byte_addressing.cc.html#L7'>rname_8bit</a><span class="Delimiter">(</span>rm<span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L27" class="LineNr"> 27 </span>    <span class="Identifier">return</span> <a href='021byte_addressing.cc.html#L33'>reg_8bit</a><span class="Delimiter">(</span>rm<span class="Delimiter">);</span>
<span id="L28" class="LineNr"> 28 </span>  <span class="Delimiter">}</span>
<span id="L29" class="LineNr"> 29 </span>  <span class="Comment">// the rest is as usual</span>
<span id="L30" class="LineNr"> 30 </span>  <span class="Identifier">return</span> <a href='010---vm.cc.html#L180'>mem_addr_u8</a><span class="Delimiter">(</span><a href='013direct_addressing.cc.html#L116'>effective_address_number</a><span class="Delimiter">(</span>modrm<span class="Delimiter">));</span>
<span id="L31" class="LineNr"> 31 </span><span class="Delimiter">}</span>
<span id="L32" class="LineNr"> 32 </span>
<span id="L33" class="LineNr"> 33 </span><span class="Normal">uint8_t</span>* <a href='021byte_addressing.cc.html#L33'>reg_8bit</a><span class="Delimiter">(</span><span class="Normal">uint8_t</span> rm<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L34" class="LineNr"> 34 </span>  <span class="Normal">uint8_t</span>* result = <span class="Normal">reinterpret_cast</span>&lt;<span class="Normal">uint8_t</span>*&gt;<span class="Delimiter">(</span>&amp;<span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[rm &amp; <span class="Constant">0x3</span>]<span class="Delimiter">.</span>i<span class="Delimiter">);</span>  <span class="Comment">// _L register</span>
<span id="L35" class="LineNr"> 35 </span>  <span class="Normal">if</span> <span class="Delimiter">(</span>rm &amp; <span class="Constant">0x4</span><span class="Delimiter">)</span>
<span id="L36" class="LineNr"> 36 </span>    ++result<span class="Delimiter">;</span>  <span class="Comment">// _H register;  assumes host is little-endian</span>
<span id="L37" class="LineNr"> 37 </span>  <span class="Identifier">return</span> result<span class="Delimiter">;</span>
<span id="L38" class="LineNr"> 38 </span><span class="Delimiter">}</span>
<span id="L39" class="LineNr"> 39 </span>
<span id="L40" class="LineNr"> 40 </span><span class="Delimiter">:(before &quot;End Initialize Op Names&quot;)</span>
<span id="L41" class="LineNr"> 41 </span><a href='001help.cc.html#L239'>put_new</a><span class="Delimiter">(</span><span class="Special"><a href='010---vm.cc.html#L342'>Name</a></span><span class="Delimiter">,</span> <span class="Constant">&quot;88&quot;</span><span class="Delimiter">,</span> <span class="Constant">&quot;copy r8 to r8/m8-at-r32&quot;</span><span class="Delimiter">);</span>
<span id="L42" class="LineNr"> 42 </span>
<span id="L43" class="LineNr"> 43 </span><span class="Delimiter">:(code)</span>
<span id="L44" class="LineNr"> 44 </span><span class="Normal">void</span> <a href='021byte_addressing.cc.html#L44'>test_copy_r8_to_mem_at_r32</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L45" class="LineNr"> 45 </span>  <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[EBX]<span class="Delimiter">.</span>i = <span class="Constant">0x224488ab</span><span class="Delimiter">;</span>
<span id="L46" class="LineNr"> 46 </span>  <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[EAX]<span class="Delimiter">.</span>i = <span class="Constant">0x2000</span><span class="Delimiter">;</span>
<span id="L47" class="LineNr"> 47 </span>  <a href='011run.cc.html#L82'>run</a><span class="Delimiter">(</span>
<span id="L48" class="LineNr"> 48 </span>      <span class="Constant">&quot;== code 0x1\n&quot;</span>
<span id="L49" class="LineNr"> 49 </span>      <span class="Comment">// op     ModR/M  SIB   displacement  immediate</span>
<span id="L50" class="LineNr"> 50 </span>      <span class="Constant">&quot;  88     18                                      \n&quot;</span>  <span class="Comment">// copy BL to the byte at *EAX</span>
<span id="L51" class="LineNr"> 51 </span>      <span class="Comment">// ModR/M in binary: 00 (indirect mode) 011 (src BL) 000 (dest EAX)</span>
<span id="L52" class="LineNr"> 52 </span>      <span class="Constant">&quot;== data 0x2000\n&quot;</span>
<span id="L53" class="LineNr"> 53 </span>      <span class="Constant">&quot;f0 cc bb aa\n&quot;</span>
<span id="L54" class="LineNr"> 54 </span>  <span class="Delimiter">);</span>
<span id="L55" class="LineNr"> 55 </span>  <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a><span class="Delimiter">(</span>
<span id="L56" class="LineNr"> 56 </span>      <span class="Constant">&quot;run: copy BL to r8/m8-at-r32\n&quot;</span>
<span id="L57" class="LineNr"> 57 </span>      <span class="Constant">&quot;run: effective address is 0x00002000 (<a href='010---vm.cc.html#L10'>EAX</a>)\n&quot;</span>
<span id="L58" class="LineNr"> 58 </span>      <span class="Constant">&quot;run: storing 0xab\n&quot;</span>
<span id="L59" class="LineNr"> 59 </span>  <span class="Delimiter">);</span>
<span id="L60" class="LineNr"> 60 </span>  <a href='002test.cc.html#L31'>CHECK_EQ</a><span class="Delimiter">(</span><span class="Constant">0xaabbccab</span><span class="Delimiter">,</span> <a href='010---vm.cc.html#L172'>read_mem_u32</a><span class="Delimiter">(</span><span class="Constant">0x2000</span><span class="Delimiter">));</span>
<span id="L61" class="LineNr"> 61 </span><span class="Delimiter">}</span>
<span id="L62" class="LineNr"> 62 </span>
<span id="L63" class="LineNr"> 63 </span><span class="Delimiter">:(before &quot;End Single-Byte Opcodes&quot;)</span>
<span id="L64" class="LineNr"> 64 </span><span class="Normal">case</span> <span class="Constant">0x88</span>: <span class="Delimiter">{</span>  <span class="Comment">// copy r8 to r/m8</span>
<span id="L65" class="LineNr"> 65 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> modrm = <a href='010---vm.cc.html#L325'>next</a><span class="Delimiter">();</span>
<span id="L66" class="LineNr"> 66 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> rsrc = <span class="Delimiter">(</span>modrm&gt;&gt;<span class="Constant">3</span><span class="Delimiter">)</span>&amp;<span class="Constant">0x7</span><span class="Delimiter">;</span>
<span id="L67" class="LineNr"> 67 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;copy &quot;</span> &lt;&lt; <a href='021byte_addressing.cc.html#L7'>rname_8bit</a><span class="Delimiter">(</span>rsrc<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot; to r8/m8-at-r32&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L68" class="LineNr"> 68 </span>  <span class="Comment">// use unsigned to zero-extend 8-bit value to 32 bits</span>
<span id="L69" class="LineNr"> 69 </span>  <span class="Normal">uint8_t</span>* dest = <span class="Normal">reinterpret_cast</span>&lt;<span class="Normal">uint8_t</span>*&gt;<span class="Delimiter">(</span><a href='021byte_addressing.cc.html#L21'>effective_byte_address</a><span class="Delimiter">(</span>modrm<span class="Delimiter">));</span>
<span id="L70" class="LineNr"> 70 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span>* src = <a href='021byte_addressing.cc.html#L33'>reg_8bit</a><span class="Delimiter">(</span>rsrc<span class="Delimiter">);</span>
<span id="L71" class="LineNr"> 71 </span>  *dest = *src<span class="Delimiter">;</span>
<span id="L72" class="LineNr"> 72 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;storing 0x&quot;</span> &lt;&lt; <a href='010---vm.cc.html#L394'>HEXBYTE</a> &lt;&lt; <a href='010---vm.cc.html#L397'>NUM</a><span class="Delimiter">(</span>*dest<span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L73" class="LineNr"> 73 </span>  <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L74" class="LineNr"> 74 </span><span class="Delimiter">}</span>
<span id="L75" class="LineNr"> 75 </span>
<span id="L76" class="LineNr"> 76 </span><span class="Comment">//:</span>
<span id="L77" class="LineNr"> 77 </span>
<span id="L78" class="LineNr"> 78 </span><span class="Delimiter">:(before &quot;End Initialize Op Names&quot;)</span>
<span id="L79" class="LineNr"> 79 </span><a href='001help.cc.html#L239'>put_new</a><span class="Delimiter">(</span><span class="Special"><a href='010---vm.cc.html#L342'>Name</a></span><span class="Delimiter">,</span> <span class="Constant">&quot;8a&quot;</span><span class="Delimiter">,</span> <span class="Constant">&quot;copy r8/m8-at-r32 to r8&quot;</span><span class="Delimiter">);</span>
<span id="L80" class="LineNr"> 80 </span>
<span id="L81" class="LineNr"> 81 </span><span class="Delimiter">:(code)</span>
<span id="L82" class="LineNr"> 82 </span><span class="Normal">void</span> <a href='021byte_addressing.cc.html#L82'>test_copy_mem_at_r32_to_r8</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L83" class="LineNr"> 83 </span>  <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[EBX]<span class="Delimiter">.</span>i = <span class="Constant">0xaabbcc0f</span><span class="Delimiter">;</span>  <span class="Comment">// one nibble each of lowest byte set to all 0s and all 1s, to maximize value of this test</span>
<span id="L84" class="LineNr"> 84 </span>  <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[EAX]<span class="Delimiter">.</span>i = <span class="Constant">0x2000</span><span class="Delimiter">;</span>
<span id="L85" class="LineNr"> 85 </span>  <a href='011run.cc.html#L82'>run</a><span class="Delimiter">(</span>
<span id="L86" class="LineNr"> 86 </span>      <span class="Constant">&quot;== code 0x1\n&quot;</span>
<span id="L87" class="LineNr"> 87 </span>      <span class="Comment">// op     ModR/M  SIB   displacement  immediate</span>
<span id="L88" class="LineNr"> 88 </span>      <span class="Constant">&quot;  8a     18                                      \n&quot;</span>  <span class="Comment">// copy just the byte at *EAX to BL</span>
<span id="L89" class="LineNr"> 89 </span>      <span class="Comment">// ModR/M in binary: 00 (indirect mode) 011 (dest EBX) 000 (src EAX)</span>
<span id="L90" class="LineNr"> 90 </span>      <span class="Constant">&quot;== data 0x2000\n&quot;</span>
<span id="L91" class="LineNr"> 91 </span>      <span class="Constant">&quot;ab ff ff ff\n&quot;</span>  <span class="Comment">// 0xab with more data in following bytes</span>
<span id="L92" class="LineNr"> 92 </span>  <span class="Delimiter">);</span>
<span id="L93" class="LineNr"> 93 </span>  <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a><span class="Delimiter">(</span>
<span id="L94" class="LineNr"> 94 </span>      <span class="Constant">&quot;run: copy r8/m8-at-r32 to BL\n&quot;</span>
<span id="L95" class="LineNr"> 95 </span>      <span class="Constant">&quot;run: effective address is 0x00002000 (<a href='010---vm.cc.html#L10'>EAX</a>)\n&quot;</span>
<span id="L96" class="LineNr"> 96 </span>      <span class="Constant">&quot;run: storing 0xab\n&quot;</span>
<span id="L97" class="LineNr"> 97 </span>      <span class="Comment">// remaining bytes of EBX are *not* cleared</span>
<span id="L98" class="LineNr"> 98 </span>      <span class="Constant">&quot;run: <a href='010---vm.cc.html#L13'>EBX</a> now contains 0xaabbccab\n&quot;</span>
<span id="L99" class="LineNr"> 99 </span>  <span class="Delimiter">);</span>
<span id="L100" class="LineNr">100 </span><span class="Delimiter">}</span>
<span id="L101" class="LineNr">101 </span>
<span id="L102" class="LineNr">102 </span><span class="Delimiter">:(before &quot;End Single-Byte Opcodes&quot;)</span>
<span id="L103" class="LineNr">103 </span><span class="Normal">case</span> <span class="Constant">0x8a</span>: <span class="Delimiter">{</span>  <span class="Comment">// copy r/m8 to r8</span>
<span id="L104" class="LineNr">104 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> modrm = <a href='010---vm.cc.html#L325'>next</a><span class="Delimiter">();</span>
<span id="L105" class="LineNr">105 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> rdest = <span class="Delimiter">(</span>modrm&gt;&gt;<span class="Constant">3</span><span class="Delimiter">)</span>&amp;<span class="Constant">0x7</span><span class="Delimiter">;</span>
<span id="L106" class="LineNr">106 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;copy r8/m8-at-r32 to &quot;</span> &lt;&lt; <a href='021byte_addressing.cc.html#L7'>rname_8bit</a><span class="Delimiter">(</span>rdest<span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L107" class="LineNr">107 </span>  <span class="Comment">// use unsigned to zero-extend 8-bit value to 32 bits</span>
<span id="L108" class="LineNr">108 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span>* src = <span class="Normal">reinterpret_cast</span>&lt;<span class="Normal">uint8_t</span>*&gt;<span class="Delimiter">(</span><a href='021byte_addressing.cc.html#L21'>effective_byte_address</a><span class="Delimiter">(</span>modrm<span class="Delimiter">));</span>
<span id="L109" class="LineNr">109 </span>  <span class="Normal">uint8_t</span>* dest = <a href='021byte_addressing.cc.html#L33'>reg_8bit</a><span class="Delimiter">(</span>rdest<span class="Delimiter">);</span>
<span id="L110" class="LineNr">110 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;storing 0x&quot;</span> &lt;&lt; <a href='010---vm.cc.html#L394'>HEXBYTE</a> &lt;&lt; <a href='010---vm.cc.html#L397'>NUM</a><span class="Delimiter">(</span>*src<span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L111" class="LineNr">111 </span>  *dest = *src<span class="Delimiter">;</span>
<span id="L112" class="LineNr">112 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> rdest_32bit = rdest &amp; <span class="Constant">0x3</span><span class="Delimiter">;</span>
<span id="L113" class="LineNr">113 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <a href='013direct_addressing.cc.html#L136'>rname</a><span class="Delimiter">(</span>rdest_32bit<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot; now contains 0x&quot;</span> &lt;&lt; <a href='010---vm.cc.html#L395'>HEXWORD</a> &lt;&lt; <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[rdest_32bit]<span class="Delimiter">.</span>u &lt;&lt; end<span class="Delimiter">();</span>
<span id="L114" class="LineNr">114 </span>  <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L115" class="LineNr">115 </span><span class="Delimiter">}</span>
<span id="L116" class="LineNr">116 </span>
<span id="L117" class="LineNr">117 </span><span class="Delimiter">:(code)</span>
<span id="L118" class="LineNr">118 </span><span class="Normal">void</span> <a href='021byte_addressing.cc.html#L118'>test_cannot_copy_byte_to_ESP_EBP_ESI_EDI</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L119" class="LineNr">119 </span>  <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[ESI]<span class="Delimiter">.</span>u = <span class="Constant">0xaabbccdd</span><span class="Delimiter">;</span>
<span id="L120" class="LineNr">120 </span>  <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[EBX]<span class="Delimiter">.</span>u = <span class="Constant">0x11223344</span><span class="Delimiter">;</span>
<span id="L121" class="LineNr">121 </span>  <a href='011run.cc.html#L82'>run</a><span class="Delimiter">(</span>
<span id="L122" class="LineNr">122 </span>      <span class="Constant">&quot;== code 0x1\n&quot;</span>
<span id="L123" class="LineNr">123 </span>      <span class="Comment">// op     ModR/M  SIB   displacement  immediate</span>
<span id="L124" class="LineNr">124 </span>      <span class="Constant">&quot;  8a     f3                                      \n&quot;</span>  <span class="Comment">// copy just the byte at *EBX to 8-bit register '6'</span>
<span id="L125" class="LineNr">125 </span>      <span class="Comment">// ModR/M in binary: 11 (direct mode) 110 (dest 8-bit 'register 6') 011 (src EBX)</span>
<span id="L126" class="LineNr">126 </span>  <span class="Delimiter">);</span>
<span id="L127" class="LineNr">127 </span>  <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a><span class="Delimiter">(</span>
<span id="L128" class="LineNr">128 </span>      <span class="Comment">// ensure 8-bit register '6' is DH, not ESI</span>
<span id="L129" class="LineNr">129 </span>      <span class="Constant">&quot;run: copy r8/m8-at-r32 to DH\n&quot;</span>
<span id="L130" class="LineNr">130 </span>      <span class="Constant">&quot;run: storing 0x44\n&quot;</span>
<span id="L131" class="LineNr">131 </span>  <span class="Delimiter">);</span>
<span id="L132" class="LineNr">132 </span>  <span class="Comment">// ensure ESI is unchanged</span>
<span id="L133" class="LineNr">133 </span>  <a href='002test.cc.html#L31'>CHECK_EQ</a><span class="Delimiter">(</span><span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[ESI]<span class="Delimiter">.</span>u<span class="Delimiter">,</span> <span class="Constant">0xaabbccdd</span><span class="Delimiter">);</span>
<span id="L134" class="LineNr">134 </span><span class="Delimiter">}</span>
<span id="L135" class="LineNr">135 </span>
<span id="L136" class="LineNr">136 </span><span class="Comment">//:</span>
<span id="L137" class="LineNr">137 </span>
<span id="L138" class="LineNr">138 </span><span class="Delimiter">:(before &quot;End Initialize Op Names&quot;)</span>
<span id="L139" class="LineNr">139 </span><a href='001help.cc.html#L239'>put_new</a><span class="Delimiter">(</span><span class="Special"><a href='010---vm.cc.html#L342'>Name</a></span><span class="Delimiter">,</span> <span class="Constant">&quot;c6&quot;</span><span class="Delimiter">,</span> <span class="Constant">&quot;copy imm8 to r8/m8-at-r32 (mov)&quot;</span><span class="Delimiter">);</span>
<span id="L140" class="LineNr">140 </span>
<span id="L141" class="LineNr">141 </span><span class="Delimiter">:(code)</span>
<span id="L142" class="LineNr">142 </span><span class="Normal">void</span> <a href='021byte_addressing.cc.html#L142'>test_copy_imm8_to_mem_at_r32</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L143" class="LineNr">143 </span>  <span class="Special"><a href='010---vm.cc.html#L25'>Reg</a></span>[EAX]<span class="Delimiter">.</span>i = <span class="Constant">0x2000</span><span class="Delimiter">;</span>
<span id="L144" class="LineNr">144 </span>  <a href='011run.cc.html#L82'>run</a><span class="Delimiter">(</span>
<span id="L145" class="LineNr">145 </span>      <span class="Constant">&quot;== code 0x1\n&quot;</span>
<span id="L146" class="LineNr">146 </span>      <span class="Comment">// op     ModR/M  SIB   displacement  immediate</span>
<span id="L147" class="LineNr">147 </span>      <span class="Constant">&quot;  c6     00                          dd          \n&quot;</span>  <span class="Comment">// copy to the byte at *EAX</span>
<span id="L148" class="LineNr">148 </span>      <span class="Comment">// ModR/M in binary: 00 (indirect mode) 000 (unused) 000 (dest EAX)</span>
<span id="L149" class="LineNr">149 </span>      <span class="Constant">&quot;== data 0x2000\n&quot;</span>
<span id="L150" class="LineNr">150 </span>      <span class="Constant">&quot;f0 cc bb aa\n&quot;</span>
<span id="L151" class="LineNr">151 </span>  <span class="Delimiter">);</span>
<span id="L152" class="LineNr">152 </span>  <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a><span class="Delimiter">(</span>
<span id="L153" class="LineNr">153 </span>      <span class="Constant">&quot;run: copy imm8 to r8/m8-at-r32\n&quot;</span>
<span id="L154" class="LineNr">154 </span>      <span class="Constant">&quot;run: effective address is 0x00002000 (<a href='010---vm.cc.html#L10'>EAX</a>)\n&quot;</span>
<span id="L155" class="LineNr">155 </span>      <span class="Constant">&quot;run: storing 0xdd\n&quot;</span>
<span id="L156" class="LineNr">156 </span>  <span class="Delimiter">);</span>
<span id="L157" class="LineNr">157 </span>  <a href='002test.cc.html#L31'>CHECK_EQ</a><span class="Delimiter">(</span><span class="Constant">0xaabbccdd</span><span class="Delimiter">,</span> <a href='010---vm.cc.html#L172'>read_mem_u32</a><span class="Delimiter">(</span><span class="Constant">0x2000</span><span class="Delimiter">));</span>
<span id="L158" class="LineNr">158 </span><span class="Delimiter">}</span>
<span id="L159" class="LineNr">159 </span>
<span id="L160" class="LineNr">160 </span><span class="Delimiter">:(before &quot;End Single-Byte Opcodes&quot;)</span>
<span id="L161" class="LineNr">161 </span><span class="Normal">case</span> <span class="Constant">0xc6</span>: <span class="Delimiter">{</span>  <span class="Comment">// copy imm8 to r/m8</span>
<span id="L162" class="LineNr">162 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> modrm = <a href='010---vm.cc.html#L325'>next</a><span class="Delimiter">();</span>
<span id="L163" class="LineNr">163 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> src = <a href='010---vm.cc.html#L325'>next</a><span class="Delimiter">();</span>
<span id="L164" class="LineNr">164 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;copy imm8 to r8/m8-at-r32&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L165" class="LineNr">165 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;imm8 is 0x&quot;</span> &lt;&lt; <a href='010---vm.cc.html#L395'>HEXWORD</a> &lt;&lt; <a href='010---vm.cc.html#L397'>NUM</a><span class="Delimiter">(</span>src<span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L166" class="LineNr">166 </span>  <span class="Normal">const</span> <span class="Normal">uint8_t</span> subop = <span class="Delimiter">(</span>modrm&gt;&gt;<span class="Constant">3</span><span class="Delimiter">)</span>&amp;<span class="Constant">0x7</span><span class="Delimiter">;</span>  <span class="Comment">// middle 3 'reg opcode' bits</span>
<span id="L167" class="LineNr">167 </span>  <span class="Normal">if</span> <span class="Delimiter">(</span>subop != <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L168" class="LineNr">168 </span>    cerr &lt;&lt; <span class="Constant">&quot;unrecognized subop for opcode c6: &quot;</span> &lt;&lt; <a href='010---vm.cc.html#L397'>NUM</a><span class="Delimiter">(</span>subop<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot; (only 0/copy currently implemented)\n&quot;</span><span class="Delimiter">;</span>
<span id="L169" class="LineNr">169 </span>    exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L170" class="LineNr">170 </span>  <span class="Delimiter">}</span>
<span id="L171" class="LineNr">171 </span>  <span class="Comment">// use unsigned to zero-extend 8-bit value to 32 bits</span>
<span id="L172" class="LineNr">172 </span>  <span class="Normal">uint8_t</span>* dest = <span class="Normal">reinterpret_cast</span>&lt;<span class="Normal">uint8_t</span>*&gt;<span class="Delimiter">(</span><a href='021byte_addressing.cc.html#L21'>effective_byte_address</a><span class="Delimiter">(</span>modrm<span class="Delimiter">));</span>
<span id="L173" class="LineNr">173 </span>  *dest = src<span class="Delimiter">;</span>
<span id="L174" class="LineNr">174 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Special">Callstack_depth</span>+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;storing 0x&quot;</span> &lt;&lt; <a href='010---vm.cc.html#L394'>HEXBYTE</a> &lt;&lt; <a href='010---vm.cc.html#L397'>NUM</a><span class="Delimiter">(</span>*dest<span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L175" class="LineNr">175 </span>  <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L176" class="LineNr">176 </span><span class="Delimiter">}</span>
</pre>
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