1 files changed, 121 insertions, 0 deletions
diff --git a/evdev.lua b/evdev.lua
new file mode 100644
index 0000000..dcf5a57
--- /dev/null
+++ b/evdev.lua
@@ -0,0 +1,121 @@
+local ffi = require "ffi"
+local C = ffi.C
+
+cdef_include "evdev.h"
+cdef_safe[[
+/*
+ * These definitions are copied from input-event-codes.h
+ */
+enum applause_evdev_type {
+	EV_KEY			= 0x01,
+	EV_REL			= 0x02,
+	EV_ABS			= 0x03
+};
+
+enum applause_evdev_rel {
+	REL_X			= 0x00,
+	REL_Y			= 0x01,
+	REL_Z			= 0x02,
+	REL_RX			= 0x03,
+	REL_RY			= 0x04,
+	REL_RZ			= 0x05,
+	REL_HWHEEL		= 0x06,
+	REL_DIAL		= 0x07,
+	REL_WHEEL		= 0x08,
+	REL_MISC		= 0x09,
+	REL_WHEEL_HI_RES	= 0x0b,
+	REL_HWHEEL_HI_RES	= 0x0c
+};
+
+enum applause_evdev_abs {
+	ABS_X			= 0x00,
+	ABS_Y			= 0x01,
+	ABS_Z			= 0x02
+};
+]]
+
+EvdevStream = DeriveClass(Stream)
+
+function EvdevStream:ctor(id, grab)
+	local grab = grab == nil or grab
+
+	local node
+	if type(id) == "number" then
+		node = "/dev/input/event"..id
+	else
+		assert(type(id) == "string")
+		-- id is assumed to be a Lua pattern to match against the device name
+		local name
+		local i = 0
+		repeat
+			node = "/dev/input/event"..i
+			local buffer = ffi.gc(C.applause_evdev_getname(node), C.free)
+			if buffer == nil then error("Evdev device not found!") end
+			name = ffi.string(buffer)
+			i = i + 1
+		until name:match(id)
+	end
+
+	-- Creating only one object has the advantage that the device can be
+	-- grabbed.
+	-- NOTE: To reliably ungrab the device, the entire object needs to be niled
+	-- and you have to drive the garbage collector manually.
+	self.evdev = ffi.gc(C.applause_evdev_new(node, grab), C.applause_evdev_free)
+	if self.evdev == nil then error("Evdev device not found!") end
+end
+
+function EvdevStream:gtick()
+	local evdev = self.evdev
+	local sample = ffi.new("applause_evdev_sample[1]")
+
+	return function()
+		-- EvdevStreams only have a single event queue no matter how often they are
+		-- gticked. That's why it must always be cached.
+		local cached_sample = sampleCache[self]
+		if not cached_sample then
+			C.applause_evdev_pull(evdev, sample)
+			sampleCache[self] = sample[0]
+			cached_sample = sample[0]
+		end
+		return cached_sample
+	end
+end
+
+-- Relative devices like some mouses and the trackpoint.
+-- The coordinate is returned in `resolution` steps between [-1, 1]
+-- NOTE: `code` is optional (default: REL_X) and you can specify a number (0 or 1)
+-- or string ('REL_X', 'REL_Y') as well.
+function Stream:evrel(code, resolution)
+	code = ffi.cast("enum applause_evdev_rel", code)
+	resolution = resolution or 1000
+	local min, max = math.min, math.max
+
+	return self:scan(function(last, sample)
+		last = last or 0
+		return sample.type == C.EV_REL and sample.code == code and
+		       min(max(last+sample.value, 0), resolution) or last
+	end) / (resolution/2) - 1
+end
+
+-- FIXME: min and max can be read from the properties of the corresponding code.
+-- This would however require us to do all postprocessing already in EvdevStream:gtick()
+-- or even in applause_evdev_new().
+function Stream:evabs(code, min, max)
+	code = ffi.cast("enum applause_evdev_abs", code)
+
+	return self:scan(function(last, sample)
+		last = last or 0
+		return sample.type == C.EV_ABS and sample.code == code and
+		       (sample.value - min)/((max-min)/2) - 1 or last
+	end)
+end
+
+-- FIXME: We haven't got constants for all KEY_X constants,#
+-- so you will have to look up the key code in input-event-codes.h.
+function Stream:evkey(key)
+	return self:scan(function(last, sample)
+		last = last or 0
+		return sample.type == C.EV_KEY and sample.code == key and
+		       sample.value or last
+	end)
+end