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[PHP] Binary waveform


Codedninja-PHP
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Well I was challenge by my teacher in school to a program off. I got the challenge done but, I see a little flaw. Well the example is at http://www.codedninja.com/programs/binary....binary=10110110 basically you put the binary you wanna show at the of the binary var. If you see it, if a number is doubled it has the extra line like 11001100 see how it has double 1's and 0's well I can fix it but I don't want the code to be really long. I would like it to be short simple. Well here is the code.

<?php
if (isset($_GET['binary'])) {
    header("Content-type: image/png");
    $im = @imagecreate(500, 500)
        or die("Cannot Initialize new GD image stream");
    $bgcolor = imagecolorallocate($im, 255, 255, 255);
    $color = imagecolorallocate($im, 0, 0, 0);
    imageline($im, 3, 3, 3, 497, $color);
    imageline($im, 3, 497, 497, 497, $color);
    $bits = str_split($_GET['binary']);
    $c = 20;
    foreach ($bits as $digit) {
      if ($digit == 0) {
        imageline($im, $c, 40, $c + 20, 40, $color);
        $c = $c + 20;
      }
      elseif ($digit == 1) {
         imageline($im, $c, 40, $c, 20, $color); 
         imageline($im, $c, 20, $c + 20, 20, $color); 
         imageline($im, $c + 20, 40, $c + 20, 20, $color);
         $c = $c + 20;
      }
    }
    imagepng($im);
    imagedestroy($im);
}
else {
    echo "Sorry, you didn't give the Binary var";
}
?>

real waveform image: http://poscope.itss.com.co/images/ExtSampling-full.jpg

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I'm not really that good with php script but one thing I see instantly is that in the image, you're treating binary as a 3bit system. It's like you have 0 as your base line, 1 as 1 and 0 as -1 and then returning to the base line after each bit.

It would be better to have your baseline as 0 and only move up to 1 when you need to, rather than moving down to -1.

For a binary model it make it look as though there are 3 values.

Here's my two cent's worth anyway.

Pseudocode:

if bit is 0 and previous bit was nothing or 0
move line one step forward

If bit is 0 and previous bit was 1
move line one step down then one step forward

if bit is 1 and previous bit was nothing or 0
move line one step up then one step forward

if bit is 1 and previous bit was 1
move line one step forward

Simplifying this would then become:

for bits
if bit is 1 and previous bit was nothing or 0
move line one step up 

else if bit is 0 and previous bit was 1
move line one step down
endif

move line one step forward
next

I hope you can follow what I mean by this, I may not have explained it very well.

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The problem is that you are drawing vertical lines on each side of a '1' bit even if there is another '1' bit on the side of it. You have to check around the current position for a '0' bit before drawing a vertical line.

This is a fixed version of your code. Hope that helps!

This (code) is a more flexible version I wrote that might impress your teacher more ;)

(reload mine a few times, the extra lines are random)

Cool exercise!

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