retroforth/doc/html/chapters/internals/io.html

86 lines
4.9 KiB
HTML
Raw Normal View History

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"><head>
<title>.</title>
<style type="text/css">
* { color: #000; background: #fff; max-width: 700px; }
tt, pre { background: #dedede; color: #111; font-family: monospace;
white-space: pre; display: block; width: 100%; }
.indentedcode { margin-left: 2em; margin-right: 2em; }
.codeblock {
background: #dedede; color: #111; font-family: monospace;
box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
padding: 7px;
display: block;
}
.indentedlist { margin-left: 2em; color: #000; }
span { white-space: pre; }
.text { color: #000; white-space: pre; background: #dedede; }
.colon { color: #000; background: #dedede; }
.note { color: #000; background: #dedede; }
.str { color: #000; text-decoration: underline; background: #dedede; }
.num { color: #000; background: #dedede; font-weight: bold; font-style: italic; }
.fnum { color: #000; font-weight: bold; background: #dedede; }
.ptr { color: #000; font-weight: bold; background: #dedede; }
.fetch { color: #000; font-style: italic; background: #dedede; }
.store { color: #000; font-style: italic; background: #dedede; }
.char { color: #000; background: #dedede; }
.inst { color: #000; background: #dedede; }
.defer { color: #000; background: #dedede; }
.imm { color: #000; font-weight: bold; background: #dedede; }
.prim { color: #000; font-weight: bolder; background: #dedede; }
.tt { white-space: pre; font-family: monospace; background: #dedede; }
.h1, .h2, .h3, .h4 { white-space: normal; }
.h1 { font-size: 125%; }
.h2 { font-size: 120%; }
.h3 { font-size: 115%; }
.h4 { font-size: 110%; }
.hr { display: block; height: 2px; background: #000000; }
</style>
</head><body>
<p><span class="h1">Internals: I/O</span>
<br/><br/>
Retro provides three words for interacting with I/O. These are:
<br/><br/>
<tt class='indentedcode'>io:enumerate&nbsp;&nbsp;&nbsp;&nbsp;returns&nbsp;the&nbsp;number&nbsp;of&nbsp;attached&nbsp;devices</tt>
<tt class='indentedcode'>io:query&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;returns&nbsp;information&nbsp;about&nbsp;a&nbsp;device</tt>
<tt class='indentedcode'>io:invoke&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;invokes&nbsp;an&nbsp;interaction&nbsp;with&nbsp;a&nbsp;device</tt>
<br/><br/>
As an example, with an implementation providing an output source,
a block storage system, and keyboard:
<br/><br/>
<tt class='indentedcode'>io:enumerate&nbsp;&nbsp;&nbsp;&nbsp;will&nbsp;return&nbsp;`3`&nbsp;since&nbsp;there&nbsp;are&nbsp;three</tt>
<tt class='indentedcode'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;i/o&nbsp;devices</tt>
<tt class='indentedcode'>#0&nbsp;io:query&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;will&nbsp;return&nbsp;0&nbsp;0,&nbsp;since&nbsp;the&nbsp;first&nbsp;device</tt>
<tt class='indentedcode'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;is&nbsp;a&nbsp;screen&nbsp;(device&nbsp;class&nbsp;0)&nbsp;with&nbsp;a&nbsp;version</tt>
<tt class='indentedcode'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;of&nbsp;0</tt>
<tt class='indentedcode'>#1&nbsp;io:query&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;will&nbsp;return&nbsp;1&nbsp;3,&nbsp;since&nbsp;the&nbsp;second&nbsp;device&nbsp;is</tt>
<tt class='indentedcode'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;block&nbsp;storage&nbsp;(device&nbsp;class&nbsp;3),&nbsp;with&nbsp;a&nbsp;version</tt>
<tt class='indentedcode'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;of&nbsp;1</tt>
<tt class='indentedcode'>#2&nbsp;io:query&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;will&nbsp;return&nbsp;0&nbsp;1,&nbsp;since&nbsp;the&nbsp;last&nbsp;device&nbsp;is&nbsp;a</tt>
<tt class='indentedcode'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;keyboard&nbsp;(device&nbsp;class&nbsp;1),&nbsp;with&nbsp;a&nbsp;version</tt>
<tt class='indentedcode'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;of&nbsp;0</tt>
<br/><br/>
In this case, some interactions can be defined:
<br/><br/>
<tt class='indentedcode'>:c:put&nbsp;#0&nbsp;io:invoke&nbsp;;</tt>
<tt class='indentedcode'>:c:get&nbsp;#2&nbsp;io:invoke&nbsp;;</tt>
<br/><br/>
Setup the stack, push the device handle, and then use <span class="tt">io:invoke</span>
to invoke the interaction.
<br/><br/>
A Retro system requires one I/O device (a generic output for a
single character). This must be the first device, and must have
a device class and handle of 0.
<br/><br/>
All other devices are optional and can be specified in any
order.
<br/><br/>
</p>
</body></html>