Merge pull request #10 from henzef/master

Allow padding with ones by using the uppercase "P" format character

bitstruct.py

@@ -30,7 +30,7 @@ def _parse_format(fmt):
         if info[0] != "":
             endianness = info[0]
 
-        if info[1] not in 'supfbtr':
+        if info[1] not in 'supPfbtr':
             raise ValueError("bad char '{}' in format".format(info[1]))
 
         infos.append((info[1], int(info[2]), endianness))
@@ -147,7 +147,7 @@ def __init__(self, fmt):
         self._number_of_arguments = 0
 
         for info in infos:
-            if info[0] != 'p':
+            if info[0] not in 'pP':
                 self._number_of_arguments += 1
 
     def pack(self, *args):
@@ -173,6 +173,8 @@ def pack(self, *args):
         for type_, size, endianness in self._infos:
             if type_ == 'p':
                 bits += size * '0'
+            elif type_ == 'P':
+                bits += size * '1'
             else:
                 if type_ == 's':
                     value_bits = _pack_integer(size, args[i])
@@ -238,7 +240,7 @@ def unpack(self, data):
         offset = 0
 
         for type_, size, endianness in self._infos:
-            if type_ == 'p':
+            if type_ in 'pP':
                 pass
             else:
                 # reverse bytes order for least significant byte first
@@ -325,7 +327,8 @@ def pack(fmt, *args):
     - ``b`` -- boolean
     - ``t`` -- text (ascii or utf-8)
     - ``r`` -- raw, bytes
-    - ``p`` -- padding, ignore
+    - ``p`` -- padding with zeros, ignore
+    - ``P`` -- padding with ones, ignore
 
     Length is the number of bits to pack the value into.
 

tests/test_bitstruct.py

@@ -33,9 +33,15 @@ def test_pack(self):
         packed = pack('p1u1s6u7u9', 0, -2, 65, 22)
         self.assertEqual(packed, b'\x3e\x82\x16')
 
+        packed = pack('P1u1s6u7u9', 0, -2, 65, 22)
+        self.assertEqual(packed, b'\xbe\x82\x16')
+
         packed = pack('p1u1s6p7u9', 0, -2, 22)
         self.assertEqual(packed, b'\x3e\x00\x16')
 
+        packed = pack('P1u1s6p7u9', 0, -2, 22)
+        self.assertEqual(packed, b'\xbe\x00\x16')
+
         packed = pack('u1s6f32r43', 0, -2, 3.75, b'\x00\xff\x00\xff\x00\xff')
         self.assertEqual(packed, b'\x7c\x80\xe0\x00\x00\x01\xfe\x01\xfe\x01\xc0')
 
@@ -45,6 +51,9 @@ def test_pack(self):
         packed = pack('b1p6b1', True, True)
         self.assertEqual(packed, b'\x81')
 
+        packed = pack('b1P6b1', True, True)
+        self.assertEqual(packed, b'\xff')
+
         packed = pack('u5b2u1', -1, False, 1)
         self.assertEqual(packed, b'\xf9')
 
@@ -130,6 +139,18 @@ def test_unpack(self):
         unpacked = unpack('s4000', packed)
         self.assertEqual(unpacked, (0, ))
 
+        packed = b'\xbe\x82\x16'
+        unpacked = unpack('P1u1s6u7u9', packed)
+        self.assertEqual(unpacked, (0, -2, 65, 22))
+
+        packed = b'\x3e\x82\x16'
+        unpacked = unpack('P1u1s6u7u9', packed)
+        self.assertEqual(unpacked, (0, -2, 65, 22))
+
+        packed = b'\xbe\x82\x16'
+        unpacked = unpack('p1u1s6u7u9', packed)
+        self.assertEqual(unpacked, (0, -2, 65, 22))
+
         packed = b'\x3e\x82\x16'
         unpacked = unpack('p1u1s6u7u9', packed)
         self.assertEqual(unpacked, (0, -2, 65, 22))
@@ -240,6 +261,9 @@ def test_calcsize(self):
         size = calcsize('b1s6u7u9p1t8')
         self.assertEqual(size, 32)
 
+        size = calcsize('b1s6u7u9P1t8')
+        self.assertEqual(size, 32)
+
     def test_byteswap(self):
         """Byte swap.
 
@@ -525,7 +549,7 @@ def test_empty_format(self):
         self.assertEqual(cf.unpack(b'\x00'), ())
 
     def test_byte_order_format(self):
-        """Test of a format with only byte order informationx.
+        """Test of a format with only byte order information.
 
         """