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<title>Mu - 028translate.cc</title>
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<a href='https://github.com/akkartik/mu/blob/master/028translate.cc'>https://github.com/akkartik/mu/blob/master/028translate.cc</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="Comment">//: The bedrock level 1 of abstraction is now done, and we're going to start</span>
<span id="L2" class="LineNr"> 2 </span><span class="Comment">//: building levels above it that make programming in x86 machine code a</span>
<span id="L3" class="LineNr"> 3 </span><span class="Comment">//: little more ergonomic.</span>
<span id="L4" class="LineNr"> 4 </span><span class="Comment">//:</span>
<span id="L5" class="LineNr"> 5 </span><span class="Comment">//: All levels will be "pass through by default". Whatever they don't</span>
<span id="L6" class="LineNr"> 6 </span><span class="Comment">//: understand they will silently pass through to lower levels.</span>
<span id="L7" class="LineNr"> 7 </span><span class="Comment">//:</span>
<span id="L8" class="LineNr"> 8 </span><span class="Comment">//: Since raw hex bytes of machine code are always possible to inject, SubX is</span>
<span id="L9" class="LineNr"> 9 </span><span class="Comment">//: not a language, and we aren't building a compiler. This is something</span>
<span id="L10" class="LineNr"> 10 </span><span class="Comment">//: deliberately leakier. Levels are more for improving auditing, checks and</span>
<span id="L11" class="LineNr"> 11 </span><span class="Comment">//: error messages rather than for hiding low-level details.</span>
<span id="L12" class="LineNr"> 12 </span>
<span id="L13" class="LineNr"> 13 </span><span class="Comment">//: Translator workflow: read 'source' file. Run a series of transforms on it,</span>
<span id="L14" class="LineNr"> 14 </span><span class="Comment">//: each passing through what it doesn't understand. The final program should</span>
<span id="L15" class="LineNr"> 15 </span><span class="Comment">//: be just machine code, suitable to write to an ELF binary.</span>
<span id="L16" class="LineNr"> 16 </span><span class="Comment">//:</span>
<span id="L17" class="LineNr"> 17 </span><span class="Comment">//: Higher levels usually transform code on the basis of metadata.</span>
<span id="L18" class="LineNr"> 18 </span>
<span id="L19" class="LineNr"> 19 </span><span class="Delimiter">:(before "End Main")</span>
<span id="L20" class="LineNr"> 20 </span><span class="Normal">if</span> <span class="Delimiter">(</span><a href='001help.cc.html#L96'>is_equal</a><span class="Delimiter">(</span>argv[<span class="Constant">1</span>]<span class="Delimiter">,</span> <span class="Constant">"translate"</span><span class="Delimiter">))</span> <span class="Delimiter">{</span>
<span id="L21" class="LineNr"> 21 </span> <span class="Comment">// Outside of tests, traces must be explicitly requested.</span>
<span id="L22" class="LineNr"> 22 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><span class="Special"><a href='003trace.cc.html#L446'>Trace_file</a></span><span class="Delimiter">.</span>is_open<span class="Delimiter">())</span> <span class="Special"><a href='003trace.cc.html#L72'>Trace_stream</a></span> = <span class="Normal">new</span> trace_stream<span class="Delimiter">;</span>
<span id="L23" class="LineNr"> 23 </span> <a href='000organization.cc.html#L148'>reset</a><span class="Delimiter">();</span>
<span id="L24" class="LineNr"> 24 </span> <span class="Comment">// Begin subx translate</span>
<span id="L25" class="LineNr"> 25 </span> program p<span class="Delimiter">;</span>
<span id="L26" class="LineNr"> 26 </span> string output_filename<span class="Delimiter">;</span>
<span id="L27" class="LineNr"> 27 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Comment">/*</span><span class="Comment">skip 'subx translate'</span><span class="Comment">*/</span><span class="Constant">2</span><span class="Delimiter">;</span> i < argc<span class="Delimiter">;</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L28" class="LineNr"> 28 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='001help.cc.html#L96'>is_equal</a><span class="Delimiter">(</span>argv[i]<span class="Delimiter">,</span> <span class="Constant">"-o"</span><span class="Delimiter">))</span> <span class="Delimiter">{</span>
<span id="L29" class="LineNr"> 29 </span> ++i<span class="Delimiter">;</span>
<span id="L30" class="LineNr"> 30 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>i >= argc<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L31" class="LineNr"> 31 </span> <a href='028translate.cc.html#L72'>print_translate_usage</a><span class="Delimiter">();</span>
<span id="L32" class="LineNr"> 32 </span> cerr << <span class="Constant">"'-o' must be followed by a filename to write results to\n"</span><span class="Delimiter">;</span>
<span id="L33" class="LineNr"> 33 </span> exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L34" class="LineNr"> 34 </span> <span class="Delimiter">}</span>
<span id="L35" class="LineNr"> 35 </span> output_filename = argv[i]<span class="Delimiter">;</span>
<span id="L36" class="LineNr"> 36 </span> <span class="Delimiter">}</span>
<span id="L37" class="LineNr"> 37 </span> <span class="Normal">else</span> <span class="Delimiter">{</span>
<span id="L38" class="LineNr"> 38 </span> <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Constant">2</span><span class="Delimiter">,</span> <span class="Constant">"parse"</span><span class="Delimiter">)</span> << argv[i] << end<span class="Delimiter">();</span>
<span id="L39" class="LineNr"> 39 </span> ifstream fin<span class="Delimiter">(</span>argv[i]<span class="Delimiter">);</span>
<span id="L40" class="LineNr"> 40 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>!fin<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L41" class="LineNr"> 41 </span> cerr << <span class="Constant">"could not open "</span> << argv[i] << <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
<span id="L42" class="LineNr"> 42 </span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L43" class="LineNr"> 43 </span> <span class="Delimiter">}</span>
<span id="L44" class="LineNr"> 44 </span> parse<span class="Delimiter">(</span>fin<span class="Delimiter">,</span> p<span class="Delimiter">);</span>
<span id="L45" class="LineNr"> 45 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='003trace.cc.html#L262'>trace_contains_errors</a><span class="Delimiter">())</span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L46" class="LineNr"> 46 </span> <span class="Delimiter">}</span>
<span id="L47" class="LineNr"> 47 </span> <span class="Delimiter">}</span>
<span id="L48" class="LineNr"> 48 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L107'>segments</a><span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Delimiter">{</span>
<span id="L49" class="LineNr"> 49 </span> <a href='028translate.cc.html#L72'>print_translate_usage</a><span class="Delimiter">();</span>
<span id="L50" class="LineNr"> 50 </span> cerr << <span class="Constant">"nothing to do; must provide at least one file to read\n"</span><span class="Delimiter">;</span>
<span id="L51" class="LineNr"> 51 </span> exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L52" class="LineNr"> 52 </span> <span class="Delimiter">}</span>
<span id="L53" class="LineNr"> 53 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>output_filename<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Delimiter">{</span>
<span id="L54" class="LineNr"> 54 </span> <a href='028translate.cc.html#L72'>print_translate_usage</a><span class="Delimiter">();</span>
<span id="L55" class="LineNr"> 55 </span> cerr << <span class="Constant">"must provide a filename to write to using '-o'\n"</span><span class="Delimiter">;</span>
<span id="L56" class="LineNr"> 56 </span> exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L57" class="LineNr"> 57 </span> <span class="Delimiter">}</span>
<span id="L58" class="LineNr"> 58 </span> <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Constant">2</span><span class="Delimiter">,</span> <span class="Constant">"transform"</span><span class="Delimiter">)</span> << <span class="Constant">"begin"</span> << end<span class="Delimiter">();</span>
<span id="L59" class="LineNr"> 59 </span> transform<span class="Delimiter">(</span>p<span class="Delimiter">);</span>
<span id="L60" class="LineNr"> 60 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='003trace.cc.html#L262'>trace_contains_errors</a><span class="Delimiter">())</span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L61" class="LineNr"> 61 </span> <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span><span class="Constant">2</span><span class="Delimiter">,</span> <span class="Constant">"translate"</span><span class="Delimiter">)</span> << <span class="Constant">"begin"</span> << end<span class="Delimiter">();</span>
<span id="L62" class="LineNr"> 62 </span> save_elf<span class="Delimiter">(</span>p<span class="Delimiter">,</span> output_filename<span class="Delimiter">);</span>
<span id="L63" class="LineNr"> 63 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='003trace.cc.html#L262'>trace_contains_errors</a><span class="Delimiter">())</span> <span class="Delimiter">{</span>
<span id="L64" class="LineNr"> 64 </span> unlink<span class="Delimiter">(</span>output_filename<span class="Delimiter">.</span>c_str<span class="Delimiter">());</span>
<span id="L65" class="LineNr"> 65 </span> <span class="Identifier">return</span> <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L66" class="LineNr"> 66 </span> <span class="Delimiter">}</span>
<span id="L67" class="LineNr"> 67 </span> <span class="Comment">// End subx translate</span>
<span id="L68" class="LineNr"> 68 </span> <span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L69" class="LineNr"> 69 </span><span class="Delimiter">}</span>
<span id="L70" class="LineNr"> 70 </span>
<span id="L71" class="LineNr"> 71 </span><span class="Delimiter">:(code)</span>
<span id="L72" class="LineNr"> 72 </span><span class="Normal">void</span> <a href='028translate.cc.html#L72'>print_translate_usage</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L73" class="LineNr"> 73 </span> cerr << <span class="Constant">"Usage: subx translate file1 file2 ... -o output\n"</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">// write out a program to a bare-bones ELF file</span>
<span id="L77" class="LineNr"> 77 </span><span class="Normal">void</span> save_elf<span class="Delimiter">(</span><span class="Normal">const</span> program& p<span class="Delimiter">,</span> <span class="Normal">const</span> string& filename<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L78" class="LineNr"> 78 </span> ofstream out<span class="Delimiter">(</span>filename<span class="Delimiter">.</span>c_str<span class="Delimiter">(),</span> ios::binary<span class="Delimiter">);</span>
<span id="L79" class="LineNr"> 79 </span> save_elf<span class="Delimiter">(</span>p<span class="Delimiter">,</span> out<span class="Delimiter">);</span>
<span id="L80" class="LineNr"> 80 </span> out<span class="Delimiter">.</span>close<span class="Delimiter">();</span>
<span id="L81" class="LineNr"> 81 </span><span class="Delimiter">}</span>
<span id="L82" class="LineNr"> 82 </span>
<span id="L83" class="LineNr"> 83 </span><span class="Normal">void</span> save_elf<span class="Delimiter">(</span><span class="Normal">const</span> program& p<span class="Delimiter">,</span> ostream& out<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L84" class="LineNr"> 84 </span> <span class="Comment">// validation: stay consistent with the self-hosted translator</span>
<span id="L85" class="LineNr"> 85 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L106'>entry</a> == <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L86" class="LineNr"> 86 </span> <a href='003trace.cc.html#L226'>raise</a> << <span class="Constant">"no 'Entry' label found\n"</span> << end<span class="Delimiter">();</span>
<span id="L87" class="LineNr"> 87 </span> <span class="Identifier">return</span><span class="Delimiter">;</span>
<span id="L88" class="LineNr"> 88 </span> <span class="Delimiter">}</span>
<span id="L89" class="LineNr"> 89 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>find<span class="Delimiter">(</span>p<span class="Delimiter">,</span> <span class="Constant">"data"</span><span class="Delimiter">)</span> == <span class="Constant">NULL</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L90" class="LineNr"> 90 </span> <a href='003trace.cc.html#L226'>raise</a> << <span class="Constant">"must include a 'data' segment\n"</span> << end<span class="Delimiter">();</span>
<span id="L91" class="LineNr"> 91 </span> <span class="Identifier">return</span><span class="Delimiter">;</span>
<span id="L92" class="LineNr"> 92 </span> <span class="Delimiter">}</span>
<span id="L93" class="LineNr"> 93 </span> <span class="Comment">// processing</span>
<span id="L94" class="LineNr"> 94 </span> <a href='028translate.cc.html#L99'>write_elf_header</a><span class="Delimiter">(</span>out<span class="Delimiter">,</span> p<span class="Delimiter">);</span>
<span id="L95" class="LineNr"> 95 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">size_t</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < p<span class="Delimiter">.</span><a href='011run.cc.html#L107'>segments</a><span class="Delimiter">.</span>size<span class="Delimiter">();</span> ++i<span class="Delimiter">)</span>
<span id="L96" class="LineNr"> 96 </span> <a href='028translate.cc.html#L195'>write_segment</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L107'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">),</span> out<span class="Delimiter">);</span>
<span id="L97" class="LineNr"> 97 </span><span class="Delimiter">}</span>
<span id="L98" class="LineNr"> 98 </span>
<span id="L99" class="LineNr"> 99 </span><span class="Normal">void</span> <a href='028translate.cc.html#L99'>write_elf_header</a><span class="Delimiter">(</span>ostream& out<span class="Delimiter">,</span> <span class="Normal">const</span> program& p<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L100" class="LineNr">100 </span> <span class="Normal">char</span> c = <span class="cSpecial">'\0'</span><span class="Delimiter">;</span>
<span id="L101" class="LineNr">101 </span><span class="PreProc">#define </span><span class="Special">O</span><span class="PreProc">(</span><span class="Special">X</span><span class="PreProc">) c = (</span><span class="Special">X</span><span class="PreProc">)</span><span class="Delimiter">;</span><span class="PreProc"> out</span><span class="Delimiter">.</span><span class="PreProc">write(&c</span><span class="Delimiter">,</span><span class="PreProc"> </span><span class="Normal">sizeof</span><span class="PreProc">(c))</span>
<span id="L102" class="LineNr">102 </span><span class="Comment">// host is required to be little-endian</span>
<span id="L103" class="LineNr">103 </span><span class="PreProc">#define emit(</span><span class="Special">X</span><span class="PreProc">) out</span><span class="Delimiter">.</span><span class="PreProc">write(</span><span class="Normal">reinterpret_cast</span><span class="PreProc"><</span><span class="Normal">const</span><span class="PreProc"> </span><span class="Normal">char</span><span class="PreProc">*>(&</span><span class="Special">X</span><span class="PreProc">)</span><span class="Delimiter">,</span><span class="PreProc"> </span><span class="Normal">sizeof</span><span class="PreProc">(</span><span class="Special">X</span><span class="PreProc">))</span>
<span id="L104" class="LineNr">104 </span> <span class="SalientComment">//// ehdr</span>
<span id="L105" class="LineNr">105 </span> <span class="Comment">// e_ident</span>
<span id="L106" class="LineNr">106 </span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x7f</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">E</span><span class="Comment">*/</span><span class="Constant">0x45</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">L</span><span class="Comment">*/</span><span class="Constant">0x4c</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Comment">/*</span><span class="Comment">F</span><span class="Comment">*/</span><span class="Constant">0x46</span><span class="Delimiter">);</span>
<span id="L107" class="LineNr">107 </span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x1</span><span class="Delimiter">);</span> <span class="Comment">// 32-bit format</span>
<span id="L108" class="LineNr">108 </span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x1</span><span class="Delimiter">);</span> <span class="Comment">// little-endian</span>
<span id="L109" class="LineNr">109 </span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x1</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x0</span><span class="Delimiter">);</span>
<span id="L110" class="LineNr">110 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">size_t</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <span class="Constant">8</span><span class="Delimiter">;</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x0</span><span class="Delimiter">);</span> <span class="Delimiter">}</span>
<span id="L111" class="LineNr">111 </span> <span class="Comment">// e_type</span>
<span id="L112" class="LineNr">112 </span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x02</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span>
<span id="L113" class="LineNr">113 </span> <span class="Comment">// e_machine</span>
<span id="L114" class="LineNr">114 </span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x03</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span>
<span id="L115" class="LineNr">115 </span> <span class="Comment">// e_version</span>
<span id="L116" class="LineNr">116 </span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x01</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span> <span class="Special">O</span><span class="Delimiter">(</span><span class="Constant">0x00</span><span class="Delimiter">);</span>
<span id="L117" class="LineNr">117 </span> <span class="Comment">// e_entry</span>
<span id="L118" class="LineNr">118 </span> <span class="Normal">uint32_t</span> e_entry = p<span class="Delimiter">.</span><a href='011run.cc.html#L106'>entry</a><span class="Delimiter">;</span>
<span id="L119" class="LineNr">119 </span> <span class="Comment">// Override e_entry</span>
<span id="L120" class="LineNr">120 </span> emit<span class="Delimiter">(</span>e_entry<span class="Delimiter">);</span>
<span id="L121" class="LineNr">121 </span> <span class="Comment">// e_phoff -- immediately after ELF header</span>
<span id="L122" class="LineNr">122 </span> <span class="Normal">uint32_t</span> e_phoff = <span class="Constant">0x34</span><span class="Delimiter">;</span>
<span id="L123" class="LineNr">123 </span> emit<span class="Delimiter">(</span>e_phoff<span class="Delimiter">);</span>
<span id="L124" class="LineNr">124 </span> <span class="Comment">// e_shoff; unused</span>
<span id="L125" class="LineNr">125 </span> <span class="Normal">uint32_t</span> dummy32 = <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L126" class="LineNr">126 </span> emit<span class="Delimiter">(</span>dummy32<span class="Delimiter">);</span>
<span id="L127" class="LineNr">127 </span> <span class="Comment">// e_flags; unused</span>
<span id="L128" class="LineNr">128 </span> emit<span class="Delimiter">(</span>dummy32<span class="Delimiter">);</span>
<span id="L129" class="LineNr">129 </span> <span class="Comment">// e_ehsize</span>
<span id="L130" class="LineNr">130 </span> <span class="Normal">uint16_t</span> e_ehsize = <span class="Constant">0x34</span><span class="Delimiter">;</span>
<span id="L131" class="LineNr">131 </span> emit<span class="Delimiter">(</span>e_ehsize<span class="Delimiter">);</span>
<span id="L132" class="LineNr">132 </span> <span class="Comment">// e_phentsize</span>
<span id="L133" class="LineNr">133 </span> <span class="Normal">uint16_t</span> e_phentsize = <span class="Constant">0x20</span><span class="Delimiter">;</span>
<span id="L134" class="LineNr">134 </span> emit<span class="Delimiter">(</span>e_phentsize<span class="Delimiter">);</span>
<span id="L135" class="LineNr">135 </span> <span class="Comment">// e_phnum</span>
<span id="L136" class="LineNr">136 </span> <span class="Normal">uint16_t</span> e_phnum = <a href='001help.cc.html#L164'>SIZE</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L107'>segments</a><span class="Delimiter">);</span>
<span id="L137" class="LineNr">137 </span> emit<span class="Delimiter">(</span>e_phnum<span class="Delimiter">);</span>
<span id="L138" class="LineNr">138 </span> <span class="Comment">// e_shentsize</span>
<span id="L139" class="LineNr">139 </span> <span class="Normal">uint16_t</span> dummy16 = <span class="Constant">0x0</span><span class="Delimiter">;</span>
<span id="L140" class="LineNr">140 </span> emit<span class="Delimiter">(</span>dummy16<span class="Delimiter">);</span>
<span id="L141" class="LineNr">141 </span> <span class="Comment">// e_shnum</span>
<span id="L142" class="LineNr">142 </span> emit<span class="Delimiter">(</span>dummy16<span class="Delimiter">);</span>
<span id="L143" class="LineNr">143 </span> <span class="Comment">// e_shstrndx</span>
<span id="L144" class="LineNr">144 </span> emit<span class="Delimiter">(</span>dummy16<span class="Delimiter">);</span>
<span id="L145" class="LineNr">145 </span>
<span id="L146" class="LineNr">146 </span> <span class="Normal">uint32_t</span> p_offset = <span class="Comment">/*</span><span class="Comment">size of ehdr</span><span class="Comment">*/</span><span class="Constant">0x34</span> + <a href='001help.cc.html#L164'>SIZE</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L107'>segments</a><span class="Delimiter">)</span>*<span class="Constant">0x20</span><span class="Comment">/*</span><span class="Comment">size of each phdr</span><span class="Comment">*/</span><span class="Delimiter">;</span>
<span id="L147" class="LineNr">147 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <a href='001help.cc.html#L164'>SIZE</a><span class="Delimiter">(</span>p<span class="Delimiter">.</span><a href='011run.cc.html#L107'>segments</a><span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L148" class="LineNr">148 </span> <span class="Normal">const</span> segment& curr = p<span class="Delimiter">.</span><a href='011run.cc.html#L107'>segments</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
<span id="L149" class="LineNr">149 </span> <span class="SalientComment">//// phdr</span>
<span id="L150" class="LineNr">150 </span> <span class="Comment">// p_type</span>
<span id="L151" class="LineNr">151 </span> <span class="Normal">uint32_t</span> p_type = <span class="Constant">0x1</span><span class="Delimiter">;</span>
<span id="L152" class="LineNr">152 </span> emit<span class="Delimiter">(</span>p_type<span class="Delimiter">);</span>
<span id="L153" class="LineNr">153 </span> <span class="Comment">// p_offset</span>
<span id="L154" class="LineNr">154 </span> emit<span class="Delimiter">(</span>p_offset<span class="Delimiter">);</span>
<span id="L155" class="LineNr">155 </span> <span class="Comment">// p_vaddr</span>
<span id="L156" class="LineNr">156 </span> <span class="Normal">uint32_t</span> p_start = curr<span class="Delimiter">.</span>start<span class="Delimiter">;</span>
<span id="L157" class="LineNr">157 </span> emit<span class="Delimiter">(</span>p_start<span class="Delimiter">);</span>
<span id="L158" class="LineNr">158 </span> <span class="Comment">// p_paddr</span>
<span id="L159" class="LineNr">159 </span> emit<span class="Delimiter">(</span>p_start<span class="Delimiter">);</span>
<span id="L160" class="LineNr">160 </span> <span class="Comment">// p_filesz</span>
<span id="L161" class="LineNr">161 </span> <span class="Normal">uint32_t</span> size = <a href='028translate.cc.html#L205'>num_words</a><span class="Delimiter">(</span>curr<span class="Delimiter">);</span>
<span id="L162" class="LineNr">162 </span> assert<span class="Delimiter">(</span>p_offset + size < <a href='010---vm.cc.html#L92'>SEGMENT_ALIGNMENT</a><span class="Delimiter">);</span>
<span id="L163" class="LineNr">163 </span> emit<span class="Delimiter">(</span>size<span class="Delimiter">);</span>
<span id="L164" class="LineNr">164 </span> <span class="Comment">// p_memsz</span>
<span id="L165" class="LineNr">165 </span> emit<span class="Delimiter">(</span>size<span class="Delimiter">);</span>
<span id="L166" class="LineNr">166 </span> <span class="Comment">// p_flags</span>
<span id="L167" class="LineNr">167 </span> <span class="Normal">uint32_t</span> p_flags = <span class="Delimiter">(</span>curr<span class="Delimiter">.</span><a href='011run.cc.html#L112'>name</a> == <span class="Constant">"code"</span><span class="Delimiter">)</span> ? <span class="Comment">/*</span><span class="Comment">r-x</span><span class="Comment">*/</span><span class="Constant">0x5</span> : <span class="Comment">/*</span><span class="Comment">rw-</span><span class="Comment">*/</span><span class="Constant">0x6</span><span class="Delimiter">;</span>
<span id="L168" class="LineNr">168 </span> emit<span class="Delimiter">(</span>p_flags<span class="Delimiter">);</span>
<span id="L169" class="LineNr">169 </span>
<span id="L170" class="LineNr">170 </span> <span class="Comment">// p_align</span>
<span id="L171" class="LineNr">171 </span> <span class="Comment">// "As the system creates or augments a process image, it logically copies</span>
<span id="L172" class="LineNr">172 </span> <span class="Comment">// a file's segment to a virtual memory segment. When—and if— the system</span>
<span id="L173" class="LineNr">173 </span> <span class="Comment">// physically reads the file depends on the program's execution behavior,</span>
<span id="L174" class="LineNr">174 </span> <span class="Comment">// system load, and so on. A process does not require a physical page</span>
<span id="L175" class="LineNr">175 </span> <span class="Comment">// unless it references the logical page during execution, and processes</span>
<span id="L176" class="LineNr">176 </span> <span class="Comment">// commonly leave many pages unreferenced. Therefore delaying physical</span>
<span id="L177" class="LineNr">177 </span> <span class="Comment">// reads frequently obviates them, improving system performance. To obtain</span>
<span id="L178" class="LineNr">178 </span> <span class="Comment">// this efficiency in practice, executable and shared object files must</span>
<span id="L179" class="LineNr">179 </span> <span class="Comment">// have segment images whose file offsets and virtual addresses are</span>
<span id="L180" class="LineNr">180 </span> <span class="Comment">// congruent, modulo the page size." -- <a href="http://refspecs.linuxbase.org/elf/elf.pdf">http://refspecs.linuxbase.org/elf/elf.pdf</a> (page 95)</span>
<span id="L181" class="LineNr">181 </span> <span class="Normal">uint32_t</span> p_align = <span class="Constant">0x1000</span><span class="Delimiter">;</span> <span class="Comment">// default page size on linux</span>
<span id="L182" class="LineNr">182 </span> emit<span class="Delimiter">(</span>p_align<span class="Delimiter">);</span>
<span id="L183" class="LineNr">183 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>p_offset % p_align != p_start % p_align<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L184" class="LineNr">184 </span> <a href='003trace.cc.html#L226'>raise</a> << <span class="Constant">"segment starting at 0x"</span> << <a href='010---vm.cc.html#L398'>HEXWORD</a> << p_start << <span class="Constant">" is improperly aligned; alignment for p_offset "</span> << p_offset << <span class="Constant">" should be "</span> << <span class="Delimiter">(</span>p_offset % p_align<span class="Delimiter">)</span> << <span class="Constant">" but is "</span> << <span class="Delimiter">(</span>p_start % p_align<span class="Delimiter">)</span> << <span class="cSpecial">'\n'</span> << end<span class="Delimiter">();</span>
<span id="L185" class="LineNr">185 </span> <span class="Identifier">return</span><span class="Delimiter">;</span>
<span id="L186" class="LineNr">186 </span> <span class="Delimiter">}</span>
<span id="L187" class="LineNr">187 </span>
<span id="L188" class="LineNr">188 </span> <span class="Comment">// prepare for next segment</span>
<span id="L189" class="LineNr">189 </span> p_offset += size<span class="Delimiter">;</span>
<span id="L190" class="LineNr">190 </span> <span class="Delimiter">}</span>
<span id="L191" class="LineNr">191 </span><span class="PreProc">#undef </span><span class="Special">O</span>
<span id="L192" class="LineNr">192 </span><span class="PreProc">#undef emit</span>
<span id="L193" class="LineNr">193 </span><span class="Delimiter">}</span>
<span id="L194" class="LineNr">194 </span>
<span id="L195" class="LineNr">195 </span><span class="Normal">void</span> <a href='028translate.cc.html#L195'>write_segment</a><span class="Delimiter">(</span><span class="Normal">const</span> segment& s<span class="Delimiter">,</span> ostream& out<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L196" class="LineNr">196 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <a href='001help.cc.html#L164'>SIZE</a><span class="Delimiter">(</span>s<span class="Delimiter">.</span><a href='011run.cc.html#L114'>lines</a><span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L197" class="LineNr">197 </span> <span class="Normal">const</span> vector<word>& w = s<span class="Delimiter">.</span><a href='011run.cc.html#L114'>lines</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L123'>words</a><span class="Delimiter">;</span>
<span id="L198" class="LineNr">198 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> j = <span class="Constant">0</span><span class="Delimiter">;</span> j < <a href='001help.cc.html#L164'>SIZE</a><span class="Delimiter">(</span>w<span class="Delimiter">);</span> ++j<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L199" class="LineNr">199 </span> <span class="Normal">uint8_t</span> x = <a href='011run.cc.html#L302'>hex_byte</a><span class="Delimiter">(</span>w<span class="Delimiter">.</span>at<span class="Delimiter">(</span>j<span class="Delimiter">).</span>data<span class="Delimiter">);</span> <span class="Comment">// we're done with metadata by this point</span>
<span id="L200" class="LineNr">200 </span> out<span class="Delimiter">.</span>write<span class="Delimiter">(</span><span class="Normal">reinterpret_cast</span><<span class="Normal">const</span> <span class="Normal">char</span>*><span class="Delimiter">(</span>&x<span class="Delimiter">),</span> <span class="Comment">/*</span><span class="Comment">sizeof(byte)</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">);</span>
<span id="L201" class="LineNr">201 </span> <span class="Delimiter">}</span>
<span id="L202" class="LineNr">202 </span> <span class="Delimiter">}</span>
<span id="L203" class="LineNr">203 </span><span class="Delimiter">}</span>
<span id="L204" class="LineNr">204 </span>
<span id="L205" class="LineNr">205 </span><span class="Normal">uint32_t</span> <a href='028translate.cc.html#L205'>num_words</a><span class="Delimiter">(</span><span class="Normal">const</span> segment& s<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L206" class="LineNr">206 </span> <span class="Normal">uint32_t</span> sum = <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L207" class="LineNr">207 </span> <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i < <a href='001help.cc.html#L164'>SIZE</a><span class="Delimiter">(</span>s<span class="Delimiter">.</span><a href='011run.cc.html#L114'>lines</a><span class="Delimiter">);</span> ++i<span class="Delimiter">)</span>
<span id="L208" class="LineNr">208 </span> sum += <a href='001help.cc.html#L164'>SIZE</a><span class="Delimiter">(</span>s<span class="Delimiter">.</span><a href='011run.cc.html#L114'>lines</a><span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span><a href='011run.cc.html#L123'>words</a><span class="Delimiter">);</span>
<span id="L209" class="LineNr">209 </span> <span class="Identifier">return</span> sum<span class="Delimiter">;</span>
<span id="L210" class="LineNr">210 </span><span class="Delimiter">}</span>
<span id="L211" class="LineNr">211 </span>
<span id="L212" class="LineNr">212 </span><span class="Delimiter">:(before "End Includes")</span>
<span id="L213" class="LineNr">213 </span><span class="Normal">using</span> std::ios<span class="Delimiter">;</span>
</pre>
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