<!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 - 313index-bounds-check.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,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy=">
<meta name="colorscheme" content="minimal-dark">
<style type="text/css">
<!--
pre { white-space: pre-wrap; font-family: monospace; color: #000000; background-color: #a8a8a8; }
body { font-size:12pt; font-family: monospace; color: #000000; background-color: #a8a8a8; }
a { color:inherit; }
* { font-size:12pt; font-size: 1em; }
.subxComment { color: #005faf; }
.subxS1Comment { color: #0000af; }
.LineNr { }
.Constant { color: #008787; }
.subxMinorFunction { color: #875f5f; }
-->
</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/main/313index-bounds-check.subx'>https://github.com/akkartik/mu/blob/main/313index-bounds-check.subx</a>
<pre id='vimCodeElement'>
<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>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment"># Really only intended to be called from code generated by mu.subx.</span>
<span id="L3" class="LineNr"> 3 </span>
<span id="L4" class="LineNr"> 4 </span>== code
<span id="L5" class="LineNr"> 5 </span>
<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>
<span id="L7" class="LineNr"> 7 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L8" class="LineNr"> 8 </span> 55/push-ebp
<span id="L9" class="LineNr"> 9 </span> 89/<- %ebp 4/r32/esp
<span id="L10" class="LineNr">10 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L11" class="LineNr">11 </span> 50/push-eax
<span id="L12" class="LineNr">12 </span> 51/push-ecx
<span id="L13" class="LineNr">13 </span> 52/push-edx
<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>
<span id="L15" class="LineNr">15 </span> <span class="subxComment"># ecx = arr-size</span>
<span id="L16" class="LineNr">16 </span> 8b/-> *(ebp+0x10) 1/r32/ecx
<span id="L17" class="LineNr">17 </span> <span class="subxComment"># var overflow/edx: int = 0</span>
<span id="L18" class="LineNr">18 </span> ba/copy-to-edx 0/imm32
<span id="L19" class="LineNr">19 </span> <span class="subxComment"># var offset/eax: int = index * elem-size</span>
<span id="L20" class="LineNr">20 </span> 8b/-> *(ebp+8) 0/r32/eax
<span id="L21" class="LineNr">21 </span> f7 4/subop/multiply-eax-with *(ebp+0xc)
<span id="L22" class="LineNr">22 </span> <span class="subxComment"># check for overflow</span>
<span id="L23" class="LineNr">23 </span> 81 7/subop/compare %edx 0/imm32
<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
<span id="L25" class="LineNr">25 </span> <span class="subxComment"># check bounds</span>
<span id="L26" class="LineNr">26 </span> 39/compare %eax 1/r32/ecx
<span id="L27" class="LineNr">27 </span> 0f 82/jump-if-unsigned< $__check-mu-array-bounds:end/disp32 <span class="subxComment"># negative index should always abort</span>
<span id="L28" class="LineNr">28 </span> <span class="subxComment"># abort if necessary</span>
<span id="L29" class="LineNr">29 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">"fn "</span> 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L30" class="LineNr">30 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x14) 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L31" class="LineNr">31 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">": offset "</span> 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L32" class="LineNr">32 </span> (<a href='501draw-text.mu.html#L312'>draw-int32-hex-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 %eax 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L33" class="LineNr">33 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">" is too large for array '"</span> 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L34" class="LineNr">34 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x18) 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L35" class="LineNr">35 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">"'"</span> 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L36" class="LineNr">36 </span> {
<span id="L37" class="LineNr">37 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L38" class="LineNr">38 </span> }
<span id="L39" class="LineNr">39 </span> <span class="subxComment"># never gets here</span>
<span id="L40" class="LineNr">40 </span><span class="Constant">$__check-mu-array-bounds:end</span>:
<span id="L41" class="LineNr">41 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L42" class="LineNr">42 </span> 5a/pop-to-edx
<span id="L43" class="LineNr">43 </span> 59/pop-to-ecx
<span id="L44" class="LineNr">44 </span> 58/pop-to-eax
<span id="L45" class="LineNr">45 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L46" class="LineNr">46 </span> 89/<- %esp 5/r32/ebp
<span id="L47" class="LineNr">47 </span> 5d/pop-to-ebp
<span id="L48" class="LineNr">48 </span> c3/return
<span id="L49" class="LineNr">49 </span>
<span id="L50" class="LineNr">50 </span><span class="subxMinorFunction">__check-mu-array-bounds:overflow</span>:
<span id="L51" class="LineNr">51 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">"fn "</span> 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L52" class="LineNr">52 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x14) 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L53" class="LineNr">53 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">": offset to array '"</span> 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L54" class="LineNr">54 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 *(ebp+0x18) 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L55" class="LineNr">55 </span> (<a href='501draw-text.mu.html#L258'>draw-text-wrapping-right-then-down-from-cursor-over-full-screen</a> 0 <span class="Constant">"' overflowed 32 bits"</span> 3 0) <span class="subxComment"># 3=cyan</span>
<span id="L56" class="LineNr">56 </span> {
<span id="L57" class="LineNr">57 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L58" class="LineNr">58 </span> }
<span id="L59" class="LineNr">59 </span> <span class="subxComment"># never gets here</span>
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->