html/313index-bounds-check.subx.html

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  55 <a href='https://github.com/akkartik/mu/blob/main/313index-bounds-check.subx'>https://github.com/akkartik/mu/blob/main/313index-bounds-check.subx</a>
  56 <pre id='vimCodeElement'>
  57 <span id="L1" class="LineNr"> 1 </span><span class="subxComment"># Helper to check an array's bounds, and to abort if they're violated.</span>
  58 <span id="L2" class="LineNr"> 2 </span><span class="subxComment"># Really only intended to be called from code generated by mu.subx.</span>
  59 <span id="L3" class="LineNr"> 3 </span>
  60 <span id="L4" class="LineNr"> 4 </span>== code
  61 <span id="L5" class="LineNr"> 5 </span>
  62 <span id="L6" class="LineNr"> 6 </span><span class="subxMinorFunction">__check-mu-array-bounds</span>:  <span class="subxComment"># index: int, elem-size: int, arr-size: int, function-name: (addr array byte), array-name: (addr array byte)</span>
  63 <span id="L7" class="LineNr"> 7 </span>    <span class="subxS1Comment"># . prologue</span>
  64 <span id="L8" class="LineNr"> 8 </span>    55/push-ebp
  65 <span id="L9" class="LineNr"> 9 </span>    89/&lt;- %ebp 4/r32/esp
  66 <span id="L10" class="LineNr">10 </span>    <span class="subxS1Comment"># . save registers</span>
  67 <span id="L11" class="LineNr">11 </span>    50/push-eax
  68 <span id="L12" class="LineNr">12 </span>    51/push-ecx
  69 <span id="L13" class="LineNr">13 </span>    52/push-edx
  70 <span id="L14" class="LineNr">14 </span>    <span class="subxS1Comment"># . not bothering saving ebx; it's only clobbered if we're going to abort</span>
  71 <span id="L15" class="LineNr">15 </span>    <span class="subxComment"># ecx = arr-size</span>
  72 <span id="L16" class="LineNr">16 </span>    8b/-&gt; *(ebp+0x10) 1/r32/ecx
  73 <span id="L17" class="LineNr">17 </span>    <span class="subxComment"># var overflow/edx: int = 0</span>
  74 <span id="L18" class="LineNr">18 </span>    ba/copy-to-edx 0/imm32
  75 <span id="L19" class="LineNr">19 </span>    <span class="subxComment"># var offset/eax: int = index * elem-size</span>
  76 <span id="L20" class="LineNr">20 </span>    8b/-&gt; *(ebp+8) 0/r32/eax
  77 <span id="L21" class="LineNr">21 </span>    f7 4/subop/multiply-eax-with *(ebp+0xc)
  78 <span id="L22" class="LineNr">22 </span>    <span class="subxComment"># check for overflow</span>
  79 <span id="L23" class="LineNr">23 </span>    81 7/subop/compare %edx 0/imm32
  80 <span id="L24" class="LineNr">24 </span>    0f 85/jump-if-!= <a href='313index-bounds-check.subx.html#L6'>__check-mu-array-bounds</a>:overflow/disp32
  81 <span id="L25" class="LineNr">25 </span>    <span class="subxComment"># check bounds</span>
  82 <span id="L26" class="LineNr">26 </span>    39/compare %eax 1/r32/ecx
  83 <span id="L27" class="LineNr">27 </span>    0f 82/jump-if-unsigned&lt; $__check-mu-array-bounds:end/disp32  <span class="subxComment"># negative index should always abort</span>
  84 <span id="L28" class="LineNr">28 </span>    <span class="subxComment"># abort if necessary</span>
  85 <span id="L29" class="LineNr">29 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">&quot;fn &quot;</span> 3 0)  <span class="subxComment"># 3=cyan</span>
  86 <span id="L30" class="LineNr">30 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x14) 3 0)  <span class="subxComment"># 3=cyan</span>
  87 <span id="L31" class="LineNr">31 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">&quot;: offset &quot;</span> 3 0)  <span class="subxComment"># 3=cyan</span>
  88 <span id="L32" class="LineNr">32 </span>    (<a href='501draw-text.mu.html#L387'>draw-int32-hex-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 %eax 3 0)  <span class="subxComment"># 3=cyan</span>
  89 <span id="L33" class="LineNr">33 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">&quot; is too large for array '&quot;</span> 3 0)  <span class="subxComment"># 3=cyan</span>
  90 <span id="L34" class="LineNr">34 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x18) 3 0)  <span class="subxComment"># 3=cyan</span>
  91 <span id="L35" class="LineNr">35 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">&quot;'&quot;</span> 3 0)  <span class="subxComment"># 3=cyan</span>
  92 <span id="L36" class="LineNr">36 </span>    (<a href='317abort.subx.html#L5'>abort</a> <span class="Constant">&quot;&quot;</span>)
  93 <span id="L37" class="LineNr">37 </span>    <span class="subxComment"># never gets here</span>
  94 <span id="L38" class="LineNr">38 </span><span class="Constant">$__check-mu-array-bounds:end</span>:
  95 <span id="L39" class="LineNr">39 </span>    <span class="subxS1Comment"># . restore registers</span>
  96 <span id="L40" class="LineNr">40 </span>    5a/pop-to-edx
  97 <span id="L41" class="LineNr">41 </span>    59/pop-to-ecx
  98 <span id="L42" class="LineNr">42 </span>    58/pop-to-eax
  99 <span id="L43" class="LineNr">43 </span>    <span class="subxS1Comment"># . epilogue</span>
 100 <span id="L44" class="LineNr">44 </span>    89/&lt;- %esp 5/r32/ebp
 101 <span id="L45" class="LineNr">45 </span>    5d/pop-to-ebp
 102 <span id="L46" class="LineNr">46 </span>    c3/return
 103 <span id="L47" class="LineNr">47 </span>
 104 <span id="L48" class="LineNr">48 </span><span class="subxMinorFunction">__check-mu-array-bounds:overflow</span>:
 105 <span id="L49" class="LineNr">49 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">&quot;fn &quot;</span> 3 0)  <span class="subxComment"># 3=cyan</span>
 106 <span id="L50" class="LineNr">50 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x14) 3 0)  <span class="subxComment"># 3=cyan</span>
 107 <span id="L51" class="LineNr">51 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">&quot;: offset to array '&quot;</span> 3 0)  <span class="subxComment"># 3=cyan</span>
 108 <span id="L52" class="LineNr">52 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x18) 3 0)  <span class="subxComment"># 3=cyan</span>
 109 <span id="L53" class="LineNr">53 </span>    (<a href='501draw-text.mu.html#L332'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">&quot;' overflowed 32 bits&quot;</span> 3 0)  <span class="subxComment"># 3=cyan</span>
 110 <span id="L54" class="LineNr">54 </span>    (<a href='317abort.subx.html#L5'>abort</a> <span class="Constant">&quot;&quot;</span>)
 111 <span id="L55" class="LineNr">55 </span>    <span class="subxComment"># never gets here</span>
 112 <span id="L56" class="LineNr">56 </span>
 113 <span id="L57" class="LineNr">57 </span><span class="subxMinorFunction">__mu-abort-null-index-base-address</span>:
 114 <span id="L58" class="LineNr">58 </span>    (<a href='317abort.subx.html#L5'>abort</a> <span class="Constant">&quot;null address in 'index'&quot;</span>)
 115 <span id="L59" class="LineNr">59 </span>
 116 <span id="L60" class="LineNr">60 </span><span class="subxMinorFunction">__mu-abort-null-get-base-address</span>:
 117 <span id="L61" class="LineNr">61 </span>    (<a href='317abort.subx.html#L5'>abort</a> <span class="Constant">&quot;null address in 'get'&quot;</span>)
 118 </pre>
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