Started on shift operations

k#

register.py

@@ -56,6 +56,7 @@ class Accumulator(Register):
     parity_flag = False
 
     def set_flags(self):
+        "Set accumulator flags after an arithmetic operation"
         self.negative_flag = False
         self.zero_flag = False
 
@@ -84,7 +85,25 @@ class Accumulator(Register):
         self.set_flags()
 
     def shift_right(self, through_carry=True):
-        pass
+        was_one = (self.get() & 1) == 1
+        if through_carry:
+            add_bit = self.carry_flag
+        else:
+            add_bit = was_one
+        if add_bit:
+            self.value |= 1 << (self.n_bits)
+        self.value >>= 1
+        self.carry_flag = was_one
+        self.set_flags()
 
     def shift_left(self, through_carry=True):
-        pass
+        was_one = (self.get() & (1 << (self.n_bits - 1))) != 0
+        if through_carry:
+            add_bit = self.carry_flag
+        else:
+            add_bit = was_one
+        self.value <<= 1
+        if add_bit:
+            self.value |= 1
+        self.carry_flag = was_one
+        self.set_flags()

test.py

@@ -0,0 +1,8 @@
+from register import Accumulator
+
+a = Accumulator(8)
+a.carry_flag = True
+a.set(8)
+print(a)
+a.shift_right(True)
+print(a)