84 lines
4.9 KiB
HTML
84 lines
4.9 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml"><head>
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<title>.</title>
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<style type="text/css">
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* { color: #000; background: #fff; max-width: 700px; }
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tt, pre { background: #dedede; color: #111; font-family: monospace;
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white-space: pre; display: block; width: 100%; }
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box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
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padding: 7px;
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display: block;
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}
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.h1, .h2, .h3, .h4 { white-space: normal; }
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.h1 { font-size: 125%; }
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.h2 { font-size: 120%; }
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.h3 { font-size: 115%; }
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.h4 { font-size: 110%; }
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</style>
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</head><body>
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<p><br/><br/>
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Retro provides three words for interacting with I/O. These are:
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<br/><br/>
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<tt class='indentedcode'>io:enumerate returns the number of attached devices</tt>
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<tt class='indentedcode'>io:query returns information about a device</tt>
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<tt class='indentedcode'>io:invoke invokes an interaction with a device</tt>
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<br/><br/>
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As an example, with an implementation providing an output source,
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a block storage system, and keyboard:
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<br/><br/>
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<tt class='indentedcode'>io:enumerate will return `3` since there are three</tt>
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<tt class='indentedcode'> i/o devices</tt>
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<tt class='indentedcode'>#0 io:query will return 0 0, since the first device</tt>
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<tt class='indentedcode'> is a screen (device class 0) with a version</tt>
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<tt class='indentedcode'> of 0</tt>
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<tt class='indentedcode'>#1 io:query will return 1 3, since the second device is</tt>
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<tt class='indentedcode'> block storage (device class 3), with a version</tt>
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<tt class='indentedcode'> of 1</tt>
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<tt class='indentedcode'>#2 io:query will return 0 1, since the last device is a</tt>
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<tt class='indentedcode'> keyboard (device class 1), with a version</tt>
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<tt class='indentedcode'> of 0</tt>
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<br/><br/>
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In this case, some interactions can be defined:
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<br/><br/>
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<tt class='indentedcode'>:c:put #0 io:invoke ;</tt>
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<tt class='indentedcode'>:c:get #2 io:invoke ;</tt>
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<br/><br/>
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Setup the stack, push the device handle, and then use <span class="tt">io:invoke</span>
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to invoke the interaction.
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<br/><br/>
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A Retro system requires one I/O device (a generic output for a
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single character). This must be the first device, and must have
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a device class and handle of 0.
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<br/><br/>
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All other devices are optional and can be specified in any
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order.
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<br/><br/>
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</p>
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</body></html>
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