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cf79ceefea
This required the change of CURSOR! signature: we now supply it with both old and new cursor positions. Also, fix broken _bs in Grid subsystem.
77 lines
2.6 KiB
Plaintext
77 lines
2.6 KiB
Plaintext
# Protocols
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Some subsystems (and in the case of KEY and EMIT, the core) re-
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quire drivers to implement certain words in a certain way. For
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example, the core requires drivers to implement (key) and (emit)
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or else it won't know how to provide a console.
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These protocols are described here.
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# TTY protocol
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(key) -- c Returns the next typed key on the console.
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If none, block until there is one.
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(emit) c -- Spit a character on the console.
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# PS/2 protocol
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This protocol enables communication with a device that spits
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PS/2 keycodes.
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(ps2kc) -- kc Returns the next typed PS/2 keycode from the
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console. Blocking.
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# SPI Relay protocol
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This protocol enables communication with a SPI relay. This
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protocol is designed to support devices with multiple endpoints.
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To that end, (spie) takes a device ID argument, with a meaning
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that is up to the device itself. To disable all devices, supply
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0 to (spie).
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We expect relay devices to support only one enabled device at
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once. Enabling a specific device is expected to disable the
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previously enabled one.
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(spie) n -- Enable SPI device
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(spix) n -- n Perform SPI exchange (push a number, get a
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number back)
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# Grid protocol
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A grid is a device that shows as a grid of ASCII characters and
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allows random access to it.
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COLS -- n Number of columns in the device
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LINES -- n Number of lines in the device
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CELL! c pos -- Set character at pos
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Optional:
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NEWLN ln -- "Enter" line ln
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CURSOR! new old -- Move cursor from old pos to new pos
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"pos" is a simple number (y * cols) + x. For example, if we
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have 40 columns per line, the position (x, y) (12, 10) is 412.
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CELL! is not expected to be called with an out-of-range char-
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acter. For example, glyphs are often mapped starting at 0x20
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(space). On most systems, CELL! should not be called with c <
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0x20.If it is, CELL! should do nothing.
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NEWLN is called when we "enter" a new line, that is, when we
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overflow from previous line or when 0x0d ( ASCII CR ) is emit-
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ted.
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When this is called, the line being entered should be cleared
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of its contents. On some systems, some kinf of screen offset
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might be have to be set to give a "scrolling" effect. Now's the
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time.
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If it's not defined, the grid system uses multiple CELL!
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calls to clear it. On some devices, this is highly inefficient.
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Drivers for those devices should define NEWLINE.
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CURSOR! is called whenever we change the cursor's position. If
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not implemented, it will be a noop. It is never called with an
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out of range "pos" (greater than COLS*LINES).
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