From 6070c23e5e1c60d3bb169e43bddfa59b1d322427 Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Thu, 16 Jan 2020 18:31:12 -0800 Subject: 5897 - rename comparison instructions Signed and unsigned don't quite capture the essence of what the different combinations of x86 flags are doing for SubX. The crucial distinction is that one set of comparison operators is for integers and the second is for addresses. --- html/062write-stream.subx.html | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'html/062write-stream.subx.html') diff --git a/html/062write-stream.subx.html b/html/062write-stream.subx.html index 2b32ebc1..f698d844 100644 --- a/html/062write-stream.subx.html +++ b/html/062write-stream.subx.html @@ -82,7 +82,7 @@ if ('onhashchange' in window) { 21 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp 22 # if (f < 0x08000000) _write-stream(f, s), return # f can't be a user-mode address, so treat it as a kernel file descriptor 23 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 0x08000000/imm32 # compare *(ebp+8) - 24 73/jump-if-greater-unsigned-or-equal $write-stream:fake/disp8 + 24 73/jump-if-addr>= $write-stream:fake/disp8 25 # . . push args 26 ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) 27 ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) @@ -165,7 +165,7 @@ if ('onhashchange' in window) { 104 cd/syscall 0x80/imm8 105 # if (eax < 0) abort 106 3d/compare-eax-with 0/imm32 -107 0f 8c/jump-if-lesser $_write-stream:abort/disp32 +107 0f 8c/jump-if-< $_write-stream:abort/disp32 108 # s->read += eax 109 01/add 1/mod/*+disp8 6/rm32/esi . . . 0/r32/eax 4/disp8 . # add eax to *(esi+4) 110 # . restore registers -- cgit 1.4.1-2-gfad0 -0700 committer Kartik Agaram <vc@akkartik.com> 2019-07-27 18:26:18 -0700 5490' href='/akkartik/mu/commit/html/055stream.subx.html?h=hlt&id=c8a3ccbeb89221d726542a89b42ddb26827af1f4'>c8a3ccbe ^ 
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<a href='https://github.com/akkartik/mu/blob/master/055stream.subx'>https://github.com/akkartik/mu/blob/master/055stream.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># streams: data structure for operating on arrays in a stateful manner</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># A stream looks like this:</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment">#   write : int  # index at which writes go</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment">#   read : int  # index that we've read until</span>
<span id="L6" class="LineNr"> 6 </span><span class="subxComment">#   data : (ref array byte)  # prefixed by length as usual</span>
<span id="L7" class="LineNr"> 7 </span><span class="subxComment">#</span>
<span id="L8" class="LineNr"> 8 </span><span class="subxComment"># some primitives for operating on streams:</span>
<span id="L9" class="LineNr"> 9 </span><span class="subxComment">#   - clear-stream (clears everything but the data length)</span>
<span id="L10" class="LineNr">10 </span><span class="subxComment">#   - rewind-stream (resets read pointer)</span>
<span id="L11" class="LineNr">11 </span>
<span id="L12" class="LineNr">12 </span>== code
<span id="L13" class="LineNr">13 </span><span class="subxComment">#   instruction                     effective address                                                   register    displacement    immediate</span>
<span id="L14" class="LineNr">14 </span><span class="subxS1Comment"># . op          subop               mod             rm32          base        index         scale       r32</span>
<span id="L15" class="LineNr">15 </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="L16" class="LineNr">16 </span>
<span id="L17" class="LineNr">17 </span><span class="subxFunction">clear-stream</span>:  <span class="subxComment"># f : (address stream byte)</span>
<span id="L18" class="LineNr">18 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L19" class="LineNr">19 </span>    55/push-ebp
<span id="L20" class="LineNr">20 </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="L21" class="LineNr">21 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L22" class="LineNr">22 </span>    50/push-eax
<span id="L23" class="LineNr">23 </span>    51/push-ecx
<span id="L24" class="LineNr">24 </span>    <span class="subxComment"># eax = f</span>
<span id="L25" class="LineNr">25 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>                        0/r32/eax   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+8) to eax</span>
<span id="L26" class="LineNr">26 </span>    <span class="subxComment"># var count/ecx : int = f-&gt;length</span>
<span id="L27" class="LineNr">27 </span>    8b/copy                         1/mod/*+disp8   0/rm32/eax   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ecx   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(eax+8) to ecx</span>
<span id="L28" class="LineNr">28 </span>    <span class="subxComment"># var max/ecx : (address byte) = &amp;f-&gt;data[f-&gt;length]</span>
<span id="L29" class="LineNr">29 </span>    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx  <span class="Normal"> . </span>          1/r32/ecx   0xc/disp8      <span class="Normal"> . </span>                <span class="subxComment"># copy eax+ecx+12 to ecx</span>
<span id="L30" class="LineNr">30 </span>    <span class="subxComment"># f-&gt;write = 0</span>
<span id="L31" class="LineNr">31 </span>    c7          0/subop/copy        0/mod/direct    0/rm32/eax   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              0/imm32           <span class="subxComment"># copy to *eax</span>
<span id="L32" class="LineNr">32 </span>    <span class="subxComment"># f-&gt;read = 0</span>
<span id="L33" class="LineNr">33 </span>    c7          0/subop/copy        1/mod/*+disp8   0/rm32/eax   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>          4/disp8         0/imm32           <span class="subxComment"># copy to *(eax+4)</span>
<span id="L34" class="LineNr">34 </span>    <span class="subxComment"># var curr/eax : (address byte) = f-&gt;data</span>
<span id="L35" class="LineNr">35 </span>    81          0/subop/add         3/mod/direct    0/rm32/eax   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              0xc/imm32         <span class="subxComment"># add to eax</span>
<span id="L36" class="LineNr">36 </span><span class="Constant">$clear-stream:loop</span>:
<span id="L37" class="LineNr">37 </span>    <span class="subxComment"># if (curr &gt;= max) break</span>
<span id="L38" class="LineNr">38 </span>    39/compare                      3/mod/direct    0/rm32/eax   <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 eax with ecx</span>
<span id="L39" class="LineNr">39 </span>    73/jump-if-greater-or-equal-unsigned  $clear-stream:end/disp8
<span id="L40" class="LineNr">40 </span>    <span class="subxComment"># *curr = 0</span>
<span id="L41" class="LineNr">41 </span>    c6          0/subop/copy-byte   0/mod/direct    0/rm32/eax   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              0/imm8            <span class="subxComment"># copy byte to *eax</span>
<span id="L42" class="LineNr">42 </span>    <span class="subxComment"># ++curr</span>
<span id="L43" class="LineNr">43 </span>    40/increment-eax
<span id="L44" class="LineNr">44 </span>    eb/jump  $clear-stream:<span class="Constant">loop</span>/disp8
<span id="L45" class="LineNr">45 </span><span class="Constant">$clear-stream:end</span>:
<span id="L46" class="LineNr">46 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L47" class="LineNr">47 </span>    59/pop-to-ecx
<span id="L48" class="LineNr">48 </span>    58/pop-to-eax
<span id="L49" class="LineNr">49 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L50" class="LineNr">50 </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="L51" class="LineNr">51 </span>    5d/pop-to-ebp
<span id="L52" class="LineNr">52 </span>    c3/return
<span id="L53" class="LineNr">53 </span>
<span id="L54" class="LineNr">54 </span><span class="subxFunction">rewind-stream</span>:  <span class="subxComment"># f : (address stream byte)</span>
<span id="L55" class="LineNr">55 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L56" class="LineNr">56 </span>    55/push-ebp
<span id="L57" class="LineNr">57 </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="L58" class="LineNr">58 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L59" class="LineNr">59 </span>    50/push-eax
<span id="L60" class="LineNr">60 </span>    <span class="subxComment"># eax = f</span>
<span id="L61" class="LineNr">61 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>                        0/r32/eax   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+8) to eax</span>
<span id="L62" class="LineNr">62 </span>    <span class="subxComment"># f-&gt;read = 0</span>
<span id="L63" class="LineNr">63 </span>    c7          0/subop/copy        1/mod/*+disp8   0/rm32/eax   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>          4/disp8         0/imm32           <span class="subxComment"># copy to *(eax+4)</span>
<span id="L64" class="LineNr">64 </span><span class="Constant">$rewind-stream:end</span>:
<span id="L65" class="LineNr">65 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L66" class="LineNr">66 </span>    58/pop-to-eax
<span id="L67" class="LineNr">67 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L68" class="LineNr">68 </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="L69" class="LineNr">69 </span>    5d/pop-to-ebp
<span id="L70" class="LineNr">70 </span>    c3/return
<span id="L71" class="LineNr">71 </span>
<span id="L72" class="LineNr">72 </span><span class="subxS2Comment"># . . vim&#0058;nowrap:textwidth=0</span>
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generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-11-26 15:07:37 +0000