https://github.com/akkartik/mu/blob/master/032operands.cc
  1 //: Metadata for fields of an x86 instruction.
  2 //:
  3 //: The x86 instruction set is variable-length, and how a byte is interpreted
  4 //: affects later instruction boundaries. A lot of the pain in programming
  5 //: machine code stems from computer and programmer going out of sync on what
  6 //: a byte means. The miscommunication is usually not immediately caught, and
  7 //: metastasizes at runtime into kilobytes of misinterpreted instructions.
  8 //:
  9 //: To mitigate these issues, we'll start programming in terms of logical
 10 //: arguments rather than physical bytes. Some arguments are smaller than a
 11 //: byte, and others may consist of multiple bytes. This layer will correctly
 12 //: pack and order the bytes corresponding to the arguments in an instruction.
 13 
 14 :(before "End Help Texts")
 15 put_new(Help, "instructions",
 16   "Each x86 instruction consists of an instruction or opcode and some number\n"
 17   "of arguments.\n"
 18   "Each argument has a type. An instruction won't have more than one argument of\n"
 19   "any type.\n"
 20   "Each instruction has some set of allowed argument types. It'll reject others.\n"
 21   "The complete list of argument types: mod, subop, r32 (integer register),\n"
 22   "rm32 (integer register or memory), x32 (floating point register),\n"
 23   "xm32 (floating point register or memory), scale, index, base, disp8, disp16,\n"
 24   "disp32,imm8,imm32.\n"
 25   "Each of these has its own help page. Try reading 'bootstrap help mod' next.\n"
 26 );
 27 :(before "End Help Contents")
 28 cerr << "  instructions\n";
 29 
 30 :(before "Running Test Program")
 31 transform(p);
 32 if (trace_contains_errors()) return;
 33 
 34 :(code)
 35 void test_pack_immediate_constants() {
 36   run(
 37       "== code 0x1\n"
 38       "bb  0x2a/imm32\n"
 39   );
 40   CHECK_TRACE_CONTENTS(
 41       "transform: packing instruction 'bb 0x2a/imm32'\n"
 42       "transform: instruction after packing: 'bb 2a 00 00 00'\n"
 43       "run: copy imm32 0x0000002a to EBX\n"
 44   );
 45 }
 46 
 47 //: complete set of valid argument types
 48 
 49 :(before "End Globals")
 50 set<string> Instruction_arguments;
 51 :(before "End One-time Setup")
 52 Instruction_arguments.insert("subop");
 53 Instruction_arguments.insert("mod");
 54 Instruction_arguments.insert("rm32");
 55 Instruction_arguments.insert("xm32");
 56 Instruction_arguments.insert("base");
 57 Instruction_arguments.insert("index");
 58 Instruction_arguments.insert("scale");
 59 Instruction_arguments.insert("r32");
 60 Instruction_arguments.insert("x32");
 61 Instruction_arguments.insert("disp8");
 62 Instruction_arguments.insert("disp16");
 63 Instruction_arguments.insert("disp32");
 64 Instruction_arguments.insert("imm8");
 65 Instruction_arguments.insert("imm32");
 66 
 67 :(before "End Help Texts")
 68 init_argument_type_help();
 69 :(code)
 70 void init_argument_type_help() {
 71   put(Help, "mod",
 72     "2-bit argument controlling the _addressing mode_ of many instructions,\n"
 73     "to determine how to compute the _effective address_ to look up memory at\n"
 74     "based on the 'rm32' argument and potentially others.\n"
 75     "\n"
 76     "If mod = 3, just operate on the contents of the register specified by rm32\n"
 77     "            (direct mode).\n"
 78     "If mod = 2, effective a
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Mu - 105string-equal.subx</title>
<meta name="Generator" content="Vim/8.1">
<meta name="plugin-version" content="vim8.1_v1">
<meta name="syntax" content="none">
<meta name="settings" content="number_lines,use_css,no_foldcolumn,expand_tabs,line_ids,prevent_copy=">
<meta name="colorscheme" content="minimal-light">
<style type="text/css">
<!--
pre { font-family: monospace; color: #000000; background-color: #c6c6c6; }
body { font-size:12pt; font-family: monospace; color: #000000; background-color: #c6c6c6; }
a { color:inherit; }
* { font-size:12pt; font-size: 1em; }
.subxComment { color: #005faf; }
.subxS2Comment { color: #8a8a8a; }
.subxTest { color: #5f8700; }
.subxFunction { color: #af5f00; text-decoration: underline; }
.LineNr { }
.subxS1Comment { color: #0000af; }
.CommentedCode { color: #8a8a8a; }
.SpecialChar { color: #d70000; }
.Normal { color: #000000; background-color: #c6c6c6; padding-bottom: 1px; }
.Constant { color: #008787; }
.subxH1Comment { color: #005faf; text-decoration: underline; }
-->
</style>

<script type='text/javascript'>
<!--

/* function to open any folds containing a jumped-to line before jumping to it */
function JumpToLine()
{
  var lineNum;
  lineNum = window.location.hash;
  lineNum = lineNum.substr(1); /* strip off '#' */

  if (lineNum.indexOf('L') == -1) {
    lineNum = 'L'+lineNum;
  }
  var lineElem = document.getElementById(lineNum);
  /* Always jump to new location even if the line was hidden inside a fold, or
   * we corrected the raw number to a line ID.
   */
  if (lineElem) {
    lineElem.scrollIntoView(true);
  }
  return true;
}
if ('onhashchange' in window) {
  window.onhashchange = JumpToLine;
}

-->
</script>
</head>
<body onload='JumpToLine();'>
<a href='https://github.com/akkartik/mu/blob/master/105string-equal.subx'>https://github.com/akkartik/mu/blob/master/105string-equal.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr">  1 </span><span class="subxComment"># Comparing 'regular' size-prefixed strings.</span>
<span id="L2" class="LineNr">  2 </span>
<span id="L3" class="LineNr">  3 </span>== code
<span id="L4" class="LineNr">  4 </span><span class="subxComment">#   instruction                     effective address                                                   register    displacement    immediate</span>
<span id="L5" class="LineNr">  5 </span><span class="subxS1Comment"># . op          subop               mod             rm32          base        index         scale       r32</span>
<span id="L6" class="LineNr">  6 </span><span class="subxS1Comment"># . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes</span>
<span id="L7" class="LineNr">  7 </span>
<span id="L8" class="LineNr">  8 </span><span class="SpecialChar">Entry</span>:  <span class="subxComment"># run all tests</span>
<span id="L9" class="LineNr">  9 </span><span class="CommentedCode">#?     e8/call test-compare-equal-strings/disp32</span>
<span id="L10" class="LineNr"> 10 </span>    e8/call  run-tests/disp32  <span class="subxComment"># 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.</span>
<span id="L11" class="LineNr"> 11 </span>    <span class="subxComment"># syscall(exit, Num-test-failures)</span>
<span id="L12" class="LineNr"> 12 </span>    8b/copy                         0/mod/indirect  5/rm32/.disp32           <span class="Normal"> . </span>           <span class="Normal"> . </span>          3/r32/ebx   <span class="SpecialChar"><a href='102test.subx.html#L89'>Num-test-failures</a></span>/disp32          <span class="subxComment"># copy *Num-test-failures to ebx</span>
<span id="L13" class="LineNr"> 13 </span>    e8/call  syscall_exit/disp32
<span id="L14" class="LineNr"> 14 </span>
<span id="L15" class="LineNr"> 15 </span><span class="subxFunction">string-equal?</span>:  <span class="subxComment"># s: (addr array byte), benchmark: (addr array byte) -&gt; result/eax: boolean</span>
<span id="L16" class="LineNr"> 16 </span>    <span class="subxComment"># pseudocode:</span>
<span id="L17" class="LineNr"> 17 </span>    <span class="subxComment">#   if (s-&gt;size != benchmark-&gt;size) return false</span>
<span id="L18" class="LineNr"> 18 </span>    <span class="subxComment">#   return string-starts-with?(s, benchmark)</span>
<span id="L19" class="LineNr"> 19 </span>    <span class="subxComment">#</span>
<span id="L20" class="LineNr"> 20 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L21" class="LineNr"> 21 </span>    55/push-ebp
<span id="L22" class="LineNr"> 22 </span>    89/copy                         3/mod/direct    5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          4/r32/esp  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy esp to ebp</span>
<span id="L23" class="LineNr"> 23 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L24" class="LineNr"> 24 </span>    51/push-ecx
<span id="L25" class="LineNr"> 25 </span>    56/push-esi
<span id="L26" class="LineNr"> 26 </span>    57/push-edi
<span id="L27" class="LineNr"> 27 </span>    <span class="subxComment"># esi = s</span>
<span id="L28" class="LineNr"> 28 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          6/r32/esi   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+8) to esi</span>
<span id="L29" class="LineNr"> 29 </span>    <span class="subxComment"># edi = benchmark</span>
<span id="L30" class="LineNr"> 30 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          7/r32/edi   0xc/disp8      <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+12) to edi</span>
<span id="L31" class="LineNr"> 31 </span>    <span class="subxComment"># ecx = s-&gt;size</span>
<span id="L32" class="LineNr"> 32 </span>    8b/copy                         0/mod/indirect  6/rm32/esi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ecx  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy *esi to ecx</span>
<span id="L33" class="LineNr"> 33 </span><span class="Constant">$string-equal?:sizes</span>:
<span id="L34" class="LineNr"> 34 </span>    <span class="subxComment"># if (ecx != benchmark-&gt;size) return false</span>
<span id="L35" class="LineNr"> 35 </span>    39/compare                      0/mod/indirect  7/rm32/edi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ecx  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># compare *edi and ecx</span>
<span id="L36" class="LineNr"> 36 </span>    b8/copy-to-eax  0/imm32/false
<span id="L37" class="LineNr"> 37 </span>    75/jump-if-!=  $string-equal?:end/disp8
<span id="L38" class="LineNr"> 38 </span><span class="Constant">$string-equal?:contents</span>:
<span id="L39" class="LineNr"> 39 </span>    <span class="subxComment"># string-starts-with?(s, benchmark)</span>
<span id="L40" class="LineNr"> 40 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L41" class="LineNr"> 41 </span>    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>          0xc/disp8      <span class="Normal"> . </span>                <span class="subxComment"># push *(ebp+12)</span>
<span id="L42" class="LineNr"> 42 </span>    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>          8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># push *(ebp+8)</span>
<span id="L43" class="LineNr"> 43 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L44" class="LineNr"> 44 </span>    e8/call  <a href='105string-equal.subx.html#L57'>string-starts-with?</a>/disp32
<span id="L45" class="LineNr"> 45 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L46" class="LineNr"> 46 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              8/imm32           <span class="subxComment"># add to esp</span>
<span id="L47" class="LineNr"> 47 </span><span class="Constant">$string-equal?:end</span>:
<span id="L48" class="LineNr"> 48 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L49" class="LineNr"> 49 </span>    5f/pop-to-edi
<span id="L50" class="LineNr"> 50 </span>    5e/pop-to-esi
<span id="L51" class="LineNr"> 51 </span>    59/pop-to-ecx
<span id="L52" class="LineNr"> 52 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L53" class="LineNr"> 53 </span>    89/copy                         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          5/r32/ebp  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy ebp to esp</span>
<span id="L54" class="LineNr"> 54 </span>    5d/pop-to-ebp
<span id="L55" class="LineNr"> 55 </span>    c3/return
<span id="L56" class="LineNr"> 56 </span>
<span id="L57" class="LineNr"> 57 </span><span class="subxFunction">string-starts-with?</span>:  <span class="subxComment"># s: (addr array byte), benchmark: (addr array byte) -&gt; result/eax: boolean</span>
<span id="L58" class="LineNr"> 58 </span>    <span class="subxComment"># pseudocode:</span>
<span id="L59" class="LineNr"> 59 </span>    <span class="subxComment">#   if (s-&gt;size &lt; benchmark-&gt;size) return false</span>
<span id="L60" class="LineNr"> 60 </span>    <span class="subxComment">#   currs = s-&gt;data</span>
<span id="L61" class="LineNr"> 61 </span>    <span class="subxComment">#   currb = benchmark-&gt;data</span>
<span id="L62" class="LineNr"> 62 </span>    <span class="subxComment">#   maxb = &amp;benchmark-&gt;data[benchmark-&gt;size]</span>
<span id="L63" class="LineNr"> 63 </span>    <span class="subxComment">#   while currb &lt; maxb</span>
<span id="L64" class="LineNr"> 64 </span>    <span class="subxComment">#     c1 = *currs</span>
<span id="L65" class="LineNr"> 65 </span>    <span class="subxComment">#     c2 = *currb</span>
<span id="L66" class="LineNr"> 66 </span>    <span class="subxComment">#     if (c1 != c2) return false</span>
<span id="L67" class="LineNr"> 67 </span>    <span class="subxComment">#     ++currs, ++currb</span>
<span id="L68" class="LineNr"> 68 </span>    <span class="subxComment">#   return true</span>
<span id="L69" class="LineNr"> 69 </span>    <span class="subxComment">#</span>
<span id="L70" class="LineNr"> 70 </span>    <span class="subxComment"># registers:</span>
<span id="L71" class="LineNr"> 71 </span>    <span class="subxComment">#   currs: esi</span>
<span id="L72" class="LineNr"> 72 </span>    <span class="subxComment">#   maxs: ecx</span>
<span id="L73" class="LineNr"> 73 </span>    <span class="subxComment">#   currb: edi</span>
<span id="L74" class="LineNr"> 74 </span>    <span class="subxComment">#   c1: eax</span>
<span id="L75" class="LineNr"> 75 </span>    <span class="subxComment">#   c2: ebx</span>
<span id="L76" class="LineNr"> 76 </span>    <span class="subxComment">#</span>
<span id="L77" class="LineNr"> 77 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L78" class="LineNr"> 78 </span>    55/push-ebp
<span id="L79" class="LineNr"> 79 </span>    89/copy                         3/mod/direct    5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          4/r32/esp  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy esp to ebp</span>
<span id="L80" class="LineNr"> 80 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L81" class="LineNr"> 81 </span>    51/push-ecx
<span id="L82" class="LineNr"> 82 </span>    52/push-edx
<span id="L83" class="LineNr"> 83 </span>    56/push-esi
<span id="L84" class="LineNr"> 84 </span>    57/push-edi
<span id="L85" class="LineNr"> 85 </span>    <span class="subxComment"># esi = s</span>
<span id="L86" class="LineNr"> 86 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          6/r32/esi   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+8) to esi</span>
<span id="L87" class="LineNr"> 87 </span>    <span class="subxComment"># edi = benchmark</span>
<span id="L88" class="LineNr"> 88 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          7/r32/edi   0xc/disp8      <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+12) to edi</span>
<span id="L89" class="LineNr"> 89 </span>    <span class="subxComment"># var bsize/ecx: int = benchmark-&gt;size</span>
<span id="L90" class="LineNr"> 90 </span>    8b/copy                         0/mod/indirect  7/rm32/edi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ecx  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy *edi to ecx</span>
<span id="L91" class="LineNr"> 91 </span><span class="Constant">$string-starts-with?:sizes</span>:
<span id="L92" class="LineNr"> 92 </span>    <span class="subxComment"># if (s-&gt;size &lt; bsize) return false</span>
<span id="L93" class="LineNr"> 93 </span>    39/compare                      0/mod/indirect  6/rm32/esi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ecx  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># compare *esi with ecx</span>
<span id="L94" class="LineNr"> 94 </span>    7c/jump-if-&lt;  $string-starts-with?:false/disp8
<span id="L95" class="LineNr"> 95 </span>    <span class="subxComment"># var currs/esi: (addr byte) = s-&gt;data</span>
<span id="L96" class="LineNr"> 96 </span>    81          0/subop/add         3/mod/direct    6/rm32/esi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              4/imm32           <span class="subxComment"># add to esi</span>
<span id="L97" class="LineNr"> 97 </span>    <span class="subxComment"># var currb/edi: (addr byte) = benchmark-&gt;data</span>
<span id="L98" class="LineNr"> 98 </span>    81          0/subop/add         3/mod/direct    7/rm32/edi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class