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https://opencores.org/ocsvn/wb_vga/wb_vga/trunk
[/] [wb_vga/] [web_uploads/] [mouse.shtml] - Blame information for rev 10
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<!--# include virtual="/ssi/ssi_start.shtml" -->
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<link REL="stylesheet" TYPE="text/css" HREF="/people/tantos/styles.css">
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<h1>Wishbone Monitor Controller Mouse Sprite Module</h1>
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<h2>Description</h2>
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<strong>Wishbone Monitor Controller Mouse Sprite Module</strong> is a
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future extension to the existing VGA core. The need for such a module is
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pretty obvious I think. It takes a lot of time to keep track of mouse cursor position and
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prevent destroying it. Alternatively you can remove the mouse from the screen prior each WR access
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and restore it afterwards. Not only it takes a lot of time it also makes the cursor blinking and
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interfere with the refresh of the screen. HW support for mouse cursor overlay can make graphical
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application's life much easier.
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<p>
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The planned functionality will use one 512 bytes chuck on on-chip RAM.
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The 32x32 pixel image of the mouse with 2 bits per pixel is planned to be placed there. The 512
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bytes of available memory allows for 2 mouse images to be stored. The overlay engine than takes
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care of reading the content and put it on the output video data. As the memory is dual-ported
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there can no collisions occur. Thus de-coupling is not needed for this functionality and the
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overlaying can be done in the part of the core synchronized with the pixel clock.
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<p>
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The meaning of each pixel planned to be the following:
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<table border>
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<tr><td>00</td><td>No effect, transparent</td></tr>
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<tr><td>01</td><td>Invert all bits of the underlaying pixel. Allways done on all 8 pixels of the output even when BPP is less than 8.</td></tr>
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<tr><td>10</td><td>Opaue: replace output with all bits with 0s</td></tr>
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<tr><td>11</td><td>Opaue: replace output with all bits with 1s</td></tr>
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</table>
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<h2>Author & Maintainer</h2>
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<p>
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<a href="/people/tantos">Andras Tantos</a>
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