From: Joseph Spiros <joseph.spiros@ithinksw.com>
Date: Wed, 13 Apr 2011 04:40:10 +0000 (-0400)
Subject: Fixed and cleaned up signed integer reading and encoding. Implemented some value... 
X-Git-Url: http://git.ithinksw.org/~jspiros/python-ebml.git/commitdiff_plain/d8f926028d6d4368348ad27fb2c7beef29eda9c0

Fixed and cleaned up signed integer reading and encoding. Implemented some value tests.
---

diff --git a/ebml/core.py b/ebml/core.py
index 24d849f..e076c8b 100644
--- a/ebml/core.py
+++ b/ebml/core.py
@@ -138,13 +138,13 @@ def read_signed_integer(stream, size):
 	
 	value = 0
 	if size > 0:
-		byte = ord(stream.read(1))
-		if (byte & 0b10000000) == 0b10000000:
-			value = -1 << 8
-		value |= byte
+		first_byte = ord(stream.read(1))
+		value = first_byte
 		for i in xrange(1, size):
 			byte = ord(stream.read(1))
-			value = (value << 1) | byte
+			value = (value << 8) | byte
+		if (first_byte & 0b10000000) == 0b10000000:
+			value = -(2**(size*8) - value)
 	return value
 
 
@@ -391,9 +391,7 @@ def encode_signed_integer(sint, length=None):
 		if sint >= 0:
 			uint = sint
 		else:
-			uint = 0b10000000 << (length - 1)
-			uint += sint
-			uint |= 0b10000000 << (length - 1)
+			uint = 2**(length*8) - abs(sint)
 	
 	data = bytearray(length)
 	for index in reversed(xrange(length)):
diff --git a/ebml/tests/test_core.py b/ebml/tests/test_core.py
index 54a46a7..ce72b69 100644
--- a/ebml/tests/test_core.py
+++ b/ebml/tests/test_core.py
@@ -59,5 +59,48 @@ class ElementIDTests(unittest.TestCase):
 			self.assert_roundtrip(id_)
 
 
+class ValueTestCase(unittest.TestCase):
+	encoder = None
+	reader = None
+	
+	def assert_roundtrip(self, value):
+		if self.encoder is not None and self.reader is not None:
+			encoded = self.encoder(value)
+			encoded_stream = StringIO(encoded)
+			self.assertEqual(value, self.reader(encoded_stream, len(encoded)))
+		else:
+			raise NotImplementedError
+
+
+class UnsignedIntegerTests(ValueTestCase):
+	encoder = staticmethod(encode_unsigned_integer)
+	reader = staticmethod(read_unsigned_integer)
+	maximum = 2**64 - 1
+	
+	def test_random(self):
+		for value in (randint(0, self.maximum) for i in xrange(0, 10000)):
+			self.assert_roundtrip(value)
+	
+	def test_maximum(self):
+		self.assert_roundtrip(self.maximum)
+
+
+class SignedIntegerTests(ValueTestCase):
+	encoder = staticmethod(encode_signed_integer)
+	reader = staticmethod(read_signed_integer)
+	minimum = -(2**63)
+	maximum = (2**63) - 1
+	
+	def test_random(self):
+		for value in (randint(self.minimum, self.maximum) for i in xrange(0, 10000)):
+			self.assert_roundtrip(value)
+	
+	def test_minimum(self):
+		self.assert_roundtrip(self.minimum)
+	
+	def test_maximum(self):
+		self.assert_roundtrip(self.maximum)
+
+
 if __name__ == '__main__':
 	unittest.main()
\ No newline at end of file