Add range validator

lib/logitech_receiver/settings.py

@@ -24,19 +24,20 @@ _log = getLogger(__name__)
 del getLogger
 
 from copy import copy as _copy
-
+import math
 
 from .common import (
 				NamedInt as _NamedInt,
 				NamedInts as _NamedInts,
 				bytes2int as _bytes2int,
+				int2bytes as _int2bytes,
 			)
 
 #
 #
 #
 
-KIND = _NamedInts(toggle=0x01, choice=0x02, range=0x12)
+KIND = _NamedInts(toggle=0x01, choice=0x02, range=0x04)
 
 class Setting(object):
 	"""A setting descriptor.
@@ -81,6 +82,14 @@ class Setting(object):
 
 		return self._validator.choices if self._validator.kind & KIND.choice else None
 
+	@property
+	def range(self):
+		assert hasattr(self, '_value')
+		assert hasattr(self, '_device')
+
+		if self._validator.kind == KIND.range:
+			return (self._validator.min_value, self._validator.max_value)
+
 	def read(self, cached=True):
 		assert hasattr(self, '_value')
 		assert hasattr(self, '_device')
@@ -356,3 +365,36 @@ class ChoicesValidator(object):
 			raise ValueError("invalid choice %r" % new_value)
 		assert isinstance(choice, _NamedInt)
 		return choice.bytes(self._bytes_count)
+
+class RangeValidator(object):
+	__slots__ = ('min_value', 'max_value', 'flag', '_bytes_count', 'needs_current_value')
+
+	kind = KIND.range
+
+	"""Translates between integers and a byte sequence.
+	:param min_value: minimum accepted value (inclusive)
+	:param max_value: maximum accepted value (inclusive)
+	:param bytes_count: the size of the derived byte sequence. If None, it
+	will be calculated from the range."""
+	def __init__(self, min_value, max_value, bytes_count=None):
+		assert max_value > min_value
+		self.min_value = min_value
+		self.max_value = max_value
+		self.needs_current_value = False
+
+		self._bytes_count = math.ceil(math.log(max_value + 1, 256))
+		if bytes_count:
+			assert self._bytes_count <= bytes_count
+			self._bytes_count = bytes_count
+		assert self._bytes_count < 8
+
+	def validate_read(self, reply_bytes):
+		reply_value = _bytes2int(reply_bytes[:self._bytes_count])
+		assert reply_value >= self.min_value, "%s: failed to validate read value %02X" % (self.__class__.__name__, reply_value)
+		assert reply_value <= self.max_value, "%s: failed to validate read value %02X" % (self.__class__.__name__, reply_value)
+		return reply_value
+
+	def prepare_write(self, new_value, current_value=None):
+		if new_value < self.min_value or new_value > self.max_value:
+			raise ValueError("invalid choice %r" % new_value)
+		return _int2bytes(new_value, self._bytes_count)