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- # Protocols
-
- Some subsystems (and in the case of KEY and EMIT, the core) re-
- quire drivers to implement certain words in a certain way. For
- example, the core requires drivers to implement (key) and (emit)
- or else it won't know how to provide a console.
-
- These protocols are described here.
-
- # TTY protocol
-
- (key) -- c Returns the next typed key on the console.
- If none, block until there is one.
- (emit) c -- Spit a character on the console.
-
- # PS/2 protocol
-
- This protocol enables communication with a device that spits
- PS/2 keycodes.
-
- (ps2kc) -- kc Returns the next typed PS/2 keycode from the
- console. Blocking.
-
- # SPI Relay protocol
-
- This protocol enables communication with a SPI relay. This
- protocol is designed to support devices with multiple endpoints.
- To that end, (spie) takes a device ID argument, with a meaning
- that is up to the device itself. To disable all devices, supply
- 0 to (spie).
-
- We expect relay devices to support only one enabled device at
- once. Enabling a specific device is expected to disable the
- previously enabled one.
-
- (spie) n -- Enable SPI device
- (spix) n -- n Perform SPI exchange (push a number, get a
- number back)
-
- # Grid protocol
-
- A grid is a device that shows as a grid of ASCII characters and
- allows random access to it.
-
- COLS -- n Number of columns in the device
- LINES -- n Number of lines in the device
- CELL! g pos -- Set glyph at pos
-
- Optional:
- NEWLN ln -- "Enter" line ln
-
- "pos" is a simple number (y * cols) + x. For example, if we
- have 40 columns per line, the position (x, y) (12, 10) is 412.
-
- A glyph is ASCII-0x20. If the resulting glyph number exceeds the
- number of glyphs in the font, it's up to CELL! to ignore it.
-
- Glyph 0 is always blank.
-
- NEWLN is called when we "enter" a new line, that is, when we
- overflow from previous line or when 0x0d ( ASCII CR ) is emit-
- ted.
-
- When this is called, the line being entered should be cleared
- of its contents. On some systems, some kinf of screen offset
- might be have to be set to give a "scrolling" effect. Now's the
- time.
-
- If it's not defined, the grid system uses multiple CELL!
- calls to clear it. On some devices, this is highly inefficient.
- Drivers for those devices should define NEWLINE.
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