Fix RegBitField decode/encode (#242)

Author: andywongarista

sonic_platform_base/sonic_xcvr/fields/xcvr_field.py

@@ -94,15 +94,15 @@ def read_before_write(self):
         return True
 
     def decode(self, raw_data, **decoded_deps):
-        return bool((raw_data[0] >> self.bitpos) & 1)
+        return bool((raw_data[0] >> self.bitpos % 8) & 1)
 
     def encode(self, val, raw_state=None):
         assert not self.ro and raw_state is not None
         curr_state = raw_state[0]
         if val:
-            curr_state |= (1 << self.bitpos)
+            curr_state |= (1 << self.bitpos % 8)
         else:
-            curr_state &= ~(1 << self.bitpos)
+            curr_state &= ~(1 << self.bitpos % 8)
         return bytearray([curr_state])
 
 
@@ -249,7 +249,7 @@ def decode(self, raw_data, **decoded_deps):
         for field in self.fields:
             offset = field.get_offset()
             if not field.get_deps():
-                result[field.name] = field.decode(raw_data[offset - start: offset + field.get_size() - start], 
+                result[field.name] = field.decode(raw_data[offset - start: offset + field.get_size() - start],
                                               **decoded_deps)
 
         # Now decode any fields that have dependant fields in the same RegGroupField scope

tests/sonic_xcvr/test_xcvr_field.py

@@ -47,6 +47,10 @@ def __init__(self, codes):
         self.NUM_REG = NumberRegField("NumReg", 100, format=">Q", size=8, ro=False)
         self.SCALE_NUM_REG = NumberRegField("ScaleNumReg", 120, format=">i", size=4, scale=100, ro=False)
         self.FIXED_NUM_REG = FixedNumberRegField("FixedNumReg", 130, 8, format=">f", size=4, ro=False)
+        self.NUM_REG_WITH_BIT = NumberRegField("NumRegWithBit", 140,
+            RegBitField("NumRegBit", bitpos=20, ro=False),
+            format="<I", size=4, ro=False
+        )
         self.STRING_REG = StringRegField("StringReg", 12, size=15)
         self.HEX_REG = HexRegField("HexReg", 30, size=3)
         self.REG_GROUP = RegGroupField("RegGroup",
@@ -168,6 +172,10 @@ def test_encode_decode(self):
         assert field.decode(field.encode(True, bytearray(b'\x00')))
         assert not field.decode(field.encode(False, bytearray(b'\x00')))
 
+        field = mem_map.get_field("NumRegBit")
+        assert field.decode(field.encode(True, bytearray(b'\x00')))
+        assert not field.decode(field.encode(False, bytearray(b'\xFF')))
+
 class TestRegField(object):
     def test_offset(self):
         field = mem_map.get_field("Field0")