Widget:SecondPageTableDemo: Difference between revisions
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<noinclude> | <noinclude> | ||
This demonstration demonstrates the operation of a Two-level Page Table. | This demonstration demonstrates the operation of a Two-level Page Table. | ||
[{{canonicalurl:Special:ShowWidget|widget=SecondPageTableDemo}} Dark-mode widget for embedding] | |||
{{#widget:SecondPageTableDemo}} | {{#widget:SecondPageTableDemo}} | ||
</noinclude> | </noinclude> | ||
<includeonly> | <includeonly> | ||
<div id="twoLevelPageTable"> | |||
<p><canvas id="page_2_canvas" width="920" height="770"></canvas></p> | <p><canvas id="page_2_canvas" width="920" height="770"></canvas></p> | ||
<h4 id = 'mapping1'>Virtual Address in binary (8 bits)</h4> | <h4 id = 'mapping1'>Virtual Address in binary (8 bits)</h4> | ||
<h4 id = 'mapping2'>Virtual Address = L1 PageTable index (2 bits) + L2 PageTable index (2 bits) + Offset (4 bits)</h4> | <h4 id = 'mapping2'>Virtual Address = L1 PageTable index (2 bits) + L2 PageTable index (2 bits) + Offset (4 bits)</h4> | ||
<h4 id = 'mapping3'>Physical Address in binary (8 bits)</h4> | <h4 id = 'mapping3'>Physical Address in binary (8 bits)</h4> | ||
</div> | |||
<script> | <script> | ||
var | // Set to use dark theme if the body's background color is too dark | ||
var bodyColour = window.getComputedStyle(document.querySelector('body')).getPropertyValue("background-color").match(/rgba?\((.*)\)/)[1].split(',').map(Number); | |||
var usingDarkTheme; | |||
if (bodyColour[3] === 0) | |||
usingDarkTheme = false; | |||
else | |||
usingDarkTheme = bodyColour.reduce((a, b) => a + b, 0) < 255 * 1.5; | |||
// Mouse position | // Mouse position | ||
var mousePosition; | var mousePosition; | ||
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var mouseY; | var mouseY; | ||
var canvas = document.getElementById("page_2_canvas"); | var canvas = document.getElementById("page_2_canvas"); | ||
var ctx = canvas.getContext('2d'); | |||
// Constant for specifying invalid memory page | // Constant for specifying invalid memory page | ||
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function draw() { | function draw() { | ||
// Set stroke style according to theme | |||
ctx.strokeStyle = usingDarkTheme ? "white" : "black"; | |||
// Set colour of explanatory text | |||
document.getElementById("twoLevelPageTable").style.color = "white"; | |||
//Draw Virtual Memory | //Draw Virtual Memory | ||
drawVM(); | drawVM(); | ||
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function drawPageTable(label, startX, startY, blockNumber, entry, level, valid = true) { | function drawPageTable(label, startX, startY, blockNumber, entry, level, valid = true) { | ||
// Draw label | // Draw label | ||
ctx.fillStyle = "purple"; | ctx.fillStyle = usingDarkTheme ? "mediumpurple" : "purple"; | ||
ctx.font = "18px Arial"; | ctx.font = "18px Arial"; | ||
if(level == 1) | if(level == 1) | ||
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if(!valid) ctx.fillStyle = "mediumorchid"; // Table invalid | if(!valid) ctx.fillStyle = "mediumorchid"; // Table invalid | ||
else if (entry[i] == NOT_FOUND) ctx.fillStyle = "orchid"; // Entry invalid | else if (entry[i] == NOT_FOUND) ctx.fillStyle = "orchid"; // Entry invalid | ||
else ctx.fillStyle = "purple"; // Valid | else ctx.fillStyle = usingDarkTheme ? "mediumpurple" : "purple"; // Valid | ||
ctx.fillRect(startX, startY + i * BLOCK_HEIGHT, blockLength, BLOCK_HEIGHT); | ctx.fillRect(startX, startY + i * BLOCK_HEIGHT, blockLength, BLOCK_HEIGHT); | ||
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function drawPhysicalMemory() { | function drawPhysicalMemory() { | ||
// Heading | // Heading | ||
ctx.fillStyle = "blue"; | ctx.fillStyle = usingDarkTheme ? "aqua" : "blue"; | ||
ctx.font = "20px Arial"; | ctx.font = "20px Arial"; | ||
ctx.fillText("Physical Memory", 760, 80); | ctx.fillText("Physical Memory", 760, 80); | ||
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// Physical address | // Physical address | ||
ctx.fillStyle = "blue"; | ctx.fillStyle = usingDarkTheme ? "aqua" : "blue"; | ||
for (var i = 0; i < PMBlockNumber; i++) { | for (var i = 0; i < PMBlockNumber; i++) { | ||
ctx.fillText((i<<4).toString(16), PMStartx + PMBlockLength + 5, PMStarty + i * PMBlockHeight + 10); | ctx.fillText((i<<4).toString(16), PMStartx + PMBlockLength + 5, PMStarty + i * PMBlockHeight + 10); | ||
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// Draws a line with a width of 3, colour optional | // Draws a line with a width of 3, colour optional | ||
function drawLine(ctx, x, y, a, b, style = "black") { | function drawLine(ctx, x, y, a, b, style = usingDarkTheme ? "white" : "black") { | ||
ctx.lineWidth = 3; | ctx.lineWidth = 3; | ||
ctx.beginPath(); | ctx.beginPath(); | ||
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ctx.stroke(); | ctx.stroke(); | ||
ctx.lineWidth = 1; | ctx.lineWidth = 1; | ||
ctx.strokeStyle = 'black'; | ctx.strokeStyle = usingDarkTheme ? "white" : 'black'; | ||
} | } | ||
Latest revision as of 07:22, 14 August 2019
This demonstration demonstrates the operation of a Two-level Page Table.
Dark-mode widget for embedding
Virtual Address in binary (8 bits)
Virtual Address = L1 PageTable index (2 bits) + L2 PageTable index (2 bits) + Offset (4 bits)
Physical Address in binary (8 bits)
