Module `ariths_gen.multi_bit_circuits.subtractors.ripple_borrow_subtractor`

Classes

class SignedRippleBorrowSubtractor (a: Bus, b: Bus, prefix: str = '', name: str = 's_rbs', **kwargs)

Class representing signed ripple borrow subtractor.

Signed ripple borrow subtractor represents N-bit signed subtractor which is composed of N one bit subtractor, where the first is a half subtractor and rest are full subtractor. At last XOR gates are used to ensure proper sign extension.

Its downside is its long propagation delay the bigger the circuit is.

  B3 A3      B3 A3      B2 A2      B1 A1      B0 A0
  │  │       │  │       │  │       │  │       │  │
┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐
│ SIGN │ B4│      │ B3│      │ B2│      │ B1│      │
│Extend│◄──┤  FS  │◄──┤  FS  │◄──┤  FS  │◄──┤  HS  │
│      │   │      │   │      │   │      │   │      │
└──┬───┘   └──┬───┘   └──┬───┘   └──┬───┘   └──┬───┘
   ▼          ▼          ▼          ▼          ▼
  Bout        D3         D2         D1         D0

Description of the init method.

Args

a : Bus: First input bus.
b : Bus: Second input bus.
prefix : str, optional: Prefix name of signed rbs. Defaults to "".
name : str, optional: Name of signed rbs. Defaults to "s_rbs".

Expand source code

class SignedRippleBorrowSubtractor(UnsignedRippleBorrowSubtractor, GeneralCircuit):
    """Class representing signed ripple borrow subtractor.

    Signed ripple borrow subtractor represents N-bit signed subtractor which is composed of
    N one bit subtractor, where the first is a half subtractor and rest are full subtractor.
    At last XOR gates are used to ensure proper sign extension.

    Its downside is its long propagation delay the bigger the circuit is.

    ```
      B3 A3      B3 A3      B2 A2      B1 A1      B0 A0
      │  │       │  │       │  │       │  │       │  │
    ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐
    │ SIGN │ B4│      │ B3│      │ B2│      │ B1│      │
    │Extend│◄──┤  FS  │◄──┤  FS  │◄──┤  FS  │◄──┤  HS  │
    │      │   │      │   │      │   │      │   │      │
    └──┬───┘   └──┬───┘   └──┬───┘   └──┬───┘   └──┬───┘
       ▼          ▼          ▼          ▼          ▼
      Bout        D3         D2         D1         D0
    ```

    Description of the __init__ method.

    Args:
        a (Bus): First input bus.
        b (Bus): Second input bus.
        prefix (str, optional): Prefix name of signed rbs. Defaults to "".
        name (str, optional): Name of signed rbs. Defaults to "s_rbs".
    """
    def __init__(self, a: Bus, b: Bus, prefix: str = "", name: str = "s_rbs", **kwargs):
        super().__init__(a=a, b=b, prefix=prefix, name=name, signed=True, **kwargs)
        
        # Additional XOR gates to ensure correct sign extension in case of sign addition
        sign_xor_1 = XorGate(self.get_previous_component(1).a, self.get_previous_component(1).b, prefix=self.prefix+"_xor"+str(self.get_instance_num(cls=XorGate)), parent_component=self)
        self.add_component(sign_xor_1)
        sign_xor_2 = XorGate(sign_xor_1.out, self.get_previous_component(2).get_borrow_wire(), prefix=self.prefix+"_xor"+str(self.get_instance_num(cls=XorGate)), parent_component=self)
        self.add_component(sign_xor_2)
        self.out.connect(self.N, sign_xor_2.out)

Ancestors

UnsignedRippleBorrowSubtractor
GeneralCircuit

Inherited members

UnsignedRippleBorrowSubtractor:
- add_component
- get_blif_code_flat
- get_blif_code_hier
- get_c_code_flat
- get_c_code_hier
- get_cgp_code_flat
- get_circuit_blif
- get_circuit_c
- get_circuit_def
- get_circuit_gates
- get_circuit_v
- get_circuit_wire_index
- get_circuit_wires
- get_component_types
- get_declaration_blif
- get_declaration_c_flat
- get_declaration_c_hier
- get_declaration_v_flat
- get_declaration_v_hier
- get_declarations_c_hier
- get_declarations_v_hier
- get_function_blif_flat
- get_function_block_blif
- get_function_block_c
- get_function_block_v
- get_function_blocks_blif
- get_function_blocks_c
- get_function_blocks_v
- get_function_out_blif
- get_function_out_c_flat
- get_function_out_c_hier
- get_function_out_python_flat
- get_function_out_v_flat
- get_function_out_v_hier
- get_hier_subcomponent_def
- get_includes_c
- get_init_c_flat
- get_init_c_hier
- get_init_python_flat
- get_init_v_flat
- get_init_v_hier
- get_instance_num
- get_invocation_blif_hier
- get_invocations_blif_hier
- get_multi_bit_components
- get_one_bit_components
- get_out_invocation_c
- get_out_invocation_v
- get_outputs_cgp
- get_parameters_cgp
- get_previous_component
- get_prototype_blif
- get_prototype_c
- get_prototype_python
- get_prototype_v
- get_python_code_flat
- get_triplets_cgp
- get_unique_types
- get_v_code_flat
- get_v_code_hier
- save_wire_id

class UnsignedRippleBorrowSubtractor (a: Bus, b: Bus, prefix: str = '', name: str = 'u_rbs', **kwargs)

Class representing unsigned ripple borrow subtractor.

Unsigned ripple borrow subtractor represents N-bit unsigned subtractor which is composed of N one bit subtractors, where the first is a half subtractor and rest are full subtractor.

      B3 A3      B2 A2      B1 A1      B0 A0     
      │  │       │  │       │  │       │  │      
    ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐    
    │      │ B3│      │ B2│      │ B1│      │
 ┌──┤  FS  │◄──┤  FS  │◄──┤  FS  │◄──┤  HS  │
 │  │      │   │      │   │      │   │      │    
 │  └──────┘   └──────┘   └──────┘   └──────┘    
 ▼     ▼          ▼          ▼          ▼        
Bout   D3         D2         D1         D0

Description of the init method.

Args

a : Bus: First input bus.
b : Bus: Second input bus.
prefix : str, optional: Prefix name of unsigned rbs. Defaults to "".
name : str, optional: Name of unsigned rbs. Defaults to "u_rbs".

Expand source code

class UnsignedRippleBorrowSubtractor(GeneralCircuit):
    """Class representing unsigned ripple borrow subtractor.

    Unsigned ripple borrow subtractor represents N-bit unsigned subtractor which is composed of
    N one bit subtractors, where the first is a half subtractor and rest are full subtractor.
    ```
          B3 A3      B2 A2      B1 A1      B0 A0     
          │  │       │  │       │  │       │  │      
        ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐   ┌─▼──▼─┐    
        │      │ B3│      │ B2│      │ B1│      │
     ┌──┤  FS  │◄──┤  FS  │◄──┤  FS  │◄──┤  HS  │
     │  │      │   │      │   │      │   │      │    
     │  └──────┘   └──────┘   └──────┘   └──────┘    
     ▼     ▼          ▼          ▼          ▼        
    Bout   D3         D2         D1         D0       
    ```

    Description of the __init__ method.

    Args:
        a (Bus): First input bus.
        b (Bus): Second input bus.
        prefix (str, optional): Prefix name of unsigned rbs. Defaults to "".
        name (str, optional): Name of unsigned rbs. Defaults to "u_rbs".
    """
    def __init__(self, a: Bus, b: Bus, prefix: str = "", name: str = "u_rbs", **kwargs):
        self.N = max(a.N, b.N)
        super().__init__(inputs=[a, b], prefix=prefix, name=name, out_N=self.N + 1, signed_out=True, **kwargs)

        # Bus sign extension in case buses have different lengths
        self.a.bus_extend(N=self.N, prefix=a.prefix)
        self.b.bus_extend(N=self.N, prefix=b.prefix)

        # Gradual addition of 1-bit subtractor components
        for input_index in range(self.N):
            # First adder is a half subtractor
            if input_index == 0:
                obj_subtractor = HalfSubtractor(self.a.get_wire(input_index), self.b.get_wire(input_index), prefix=self.prefix+"_hs")
            # Rest adders are full subtractor
            else:
                obj_subtractor = FullSubtractor(self.a.get_wire(input_index), self.b.get_wire(input_index), obj_subtractor.get_borrow_wire(), prefix=self.prefix+"_fs"+str(input_index))

            self.add_component(obj_subtractor)
            self.out.connect(input_index, obj_subtractor.get_difference_wire())
            if input_index == (self.N-1):
                self.out.connect(self.N, obj_subtractor.get_borrow_wire())

Classes

Args

Ancestors

Inherited members

Args

Ancestors

Subclasses

Inherited members