Merge current master

1 files changed, 66 insertions, 0 deletions

diff --git a/backends/lua.md b/backends/lua.md
new file mode 100644
index 0000000..f38e189
--- /dev/null
+++ b/backends/lua.md
@@ -0,0 +1,66 @@
+### The `lua` backend
+
+The `lua` backend provides a flexible programming environment, allowing users to route and manipulate
+events using the Lua programming language.
+
+Every instance has it's own interpreter state which can be loaded with custom handler scripts.
+
+To process incoming channel events, the MIDIMonster calls corresponding Lua functions (if they exist)
+with the value (as a Lua `number` type) as parameter.
+
+The following functions are provided within the Lua interpreter for interaction with the MIDIMonster
+
+| Function			| Usage example			| Description				|
+|-------------------------------|-------------------------------|---------------------------------------|
+| `output(string, number)`	| `output("foo", 0.75)`		| Output a value event to a channel	|
+| `interval(function, number)`	| `interval(update, 100)`	| Register a function to be called periodically. Intervals are milliseconds (rounded to the nearest 10 ms) |
+| `input_value(string)`		| `input_value("foo")`		| Get the last input value on a channel	|
+| `output_value(string)`	| `output_value("bar")`		| Get the last output value on a channel |
+
+
+Example script:
+```
+function bar(value)
+	output("foo", value / 2)
+end
+
+step = 0
+function toggle()
+	output("bar", step * 1.0)
+	step = (step + 1) % 2;
+end
+
+interval(toggle, 1000)
+```
+
+Input values range between 0.0 and 1.0, output values are clamped to the same range.
+
+#### Global configuration
+
+The `lua` backend does not take any global configuration.
+
+#### Instance configuration
+
+| Option	| Example value		| Default value 	| Description		|
+|---------------|-----------------------|-----------------------|-----------------------|
+| `script`	| `script.lua`		| none			| Lua source file (relative to configuration file)|
+
+A single instance may have multiple `source` options specified, which will all be read cumulatively.
+
+#### Channel specification
+
+Channel names may be any valid Lua function name.
+
+Example mapping:
+```
+lua1.foo > lua2.bar
+```
+
+#### Known bugs / problems
+
+Using any of the interface functions (`output`, `interval`, `input_value`, `output_value`) as an
+input channel name to a Lua instance will not call any handler functions.
+Using these names as arguments to the output and value interface functions works as intended.
+
+Output values will not trigger corresponding input event handlers unless the channel is mapped
+back in the MIDIMonster configuration.