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<a href='https://github.com/akkartik/mu/blob/main/ex2.subx'>https://github.com/akkartik/mu/blob/main/ex2.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># Test out the video mode by filling in the screen with pixels.</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># To build a disk image:</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment"># ./translate_subx boot.subx ex2.subx # emits disk.img</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment"># To run:</span>
<span id="L6" class="LineNr"> 6 </span><span class="subxComment"># qemu-system-i386 disk.img</span>
<span id="L7" class="LineNr"> 7 </span><span class="subxComment"># Or:</span>
<span id="L8" class="LineNr"> 8 </span><span class="subxComment"># bochs -f bochsrc # bochsrc loads disk.img</span>
<span id="L9" class="LineNr"> 9 </span>
<span id="L10" class="LineNr">10 </span>== code
<span id="L11" class="LineNr">11 </span>
<span id="L12" class="LineNr">12 </span><span class="SpecialChar">Entry</span>:
<span id="L13" class="LineNr">13 </span> <span class="subxComment"># ecx <- start of video memory</span>
<span id="L14" class="LineNr">14 </span> 8b/-> *<span class="SpecialChar">Video-memory-addr</span> 1/r32/ecx
<span id="L15" class="LineNr">15 </span>
<span id="L16" class="LineNr">16 </span> <span class="subxComment"># eax <- final pixel of video memory</span>
<span id="L17" class="LineNr">17 </span> 8d/copy-address *(ecx + 0x0bffff) 0/r32/eax <span class="subxComment"># 0xbffff = 1024*768 - 1</span>
<span id="L18" class="LineNr">18 </span>
<span id="L19" class="LineNr">19 </span> <span class="subxComment"># for each pixel in video memory</span>
<span id="L20" class="LineNr">20 </span> {
<span id="L21" class="LineNr">21 </span> 39/compare %eax 1/r32/ecx
<span id="L22" class="LineNr">22 </span> 7c/jump-if-< <span class="Constant">break</span>/disp8
<span id="L23" class="LineNr">23 </span> <span class="subxComment"># write its column number to it</span>
<span id="L24" class="LineNr">24 </span> 88/byte<- *eax 0/r32/AL
<span id="L25" class="LineNr">25 </span> 48/decrement-eax
<span id="L26" class="LineNr">26 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L27" class="LineNr">27 </span> }
<span id="L28" class="LineNr">28 </span>
<span id="L29" class="LineNr">29 </span> <span class="subxComment"># hang indefinitely</span>
<span id="L30" class="LineNr">30 </span> {
<span id="L31" class="LineNr">31 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L32" class="LineNr">32 </span> }
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