38 lines
1.3 KiB
Text
38 lines
1.3 KiB
Text
# Internals: I/O
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Retro provides three words for interacting with I/O. These are:
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io:enumerate returns the number of attached devices
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io:query returns information about a device
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io:invoke invokes an interaction with a device
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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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io:enumerate will return `3` since there are three
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i/o devices
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#0 io:query will return 0 0, since the first device
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is a screen (device class 0) with a version
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of 0
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#1 io:query will return 1 3, since the second device is
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block storage (device class 3), with a version
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of 1
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#2 io:query will return 0 1, since the last device is a
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keyboard (device class 1), with a version
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of 0
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In this case, some interactions can be defined:
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:c:put #0 io:invoke ;
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:c:get #2 io:invoke ;
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Setup the stack, push the device handle, and then use `io:invoke`
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to invoke the interaction.
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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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All other devices are optional and can be specified in any
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order.
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