From: Stefano Rivera <stefano@rivera.za.net>
Date: Sat, 17 May 2014 15:16:20 +0000 (+0200)
Subject: Actually barrel-shift
X-Git-Tag: 0.1~92^2~1
X-Git-Url: https://git.ctpug.org.za/?p=naja.git;a=commitdiff_plain;h=8f1005d3b07d61d44d5a8a0302099126f7f2e6a9

Actually barrel-shift
---

diff --git a/naja/player.py b/naja/player.py
index b471c62..d4ff732 100644
--- a/naja/player.py
+++ b/naja/player.py
@@ -50,11 +50,12 @@ class PlayerBits(object):
             self.toggle_bit(bit)
 
     def shift_bits_left(self, shift):
-        self.bits <<= shift
+        wrap = self.bits >> (8 - shift)
+        self.bits = (self.bits << shift & 0xff | wrap)
 
     def shift_bits_right(self, shift):
-        self.bits >>= shift
-
+        wrap = self.bits << (8 - shift) & 0xff
+        self.bits = (self.bits >> shift | wrap)
 
 class Player(object):
     """
diff --git a/naja/tests/test_player.py b/naja/tests/test_player.py
index 2e17379..07583b3 100644
--- a/naja/tests/test_player.py
+++ b/naja/tests/test_player.py
@@ -85,6 +85,22 @@ class TestPlayerBits(TestCase):
         bits.toggle_bits([BITS.NORTH, BITS.BLUE, BITS.MSB])
         self.assertEqual(bits._bits, 0x92)
 
+    def test_shift_bits_left(self):
+        bits = PlayerBits(0x03)
+        self.assertEqual(bits._bits, 0x03)
+        bits.shift_bits_left(1)
+        self.assertEqual(bits._bits, 0x06)
+        bits.shift_bits_left(6)
+        self.assertEqual(bits._bits, 0x81)
+
+    def test_shift_bits_right(self):
+        bits = PlayerBits(0x06)
+        self.assertEqual(bits._bits, 0x06)
+        bits.shift_bits_right(1)
+        self.assertEqual(bits._bits, 0x03)
+        bits.shift_bits_right(1)
+        self.assertEqual(bits._bits, 0x81)
+
 
 class TestPlayer(TestCase):
     def test_new_player(self):