Arithmetic networks

The file mockturtle/generators/arithmetic.hpp implements several functions to generate arithmetic networks.

Addition and Subtraction

template<typename Ntk>
inline std::pair<signal<Ntk>, signal<Ntk>> mockturtle::full_adder(Ntk &ntk, const signal<Ntk> &a, const signal<Ntk> &b, const signal<Ntk> &c)

Inserts a full adder into a network.

Inserts a full adder for three inputs (two 1-bit operands and one carry) into the network and returns a pair of sum and carry bit.

By default creates a seven 2-input gate network composed of AND, NOR, and OR gates. If network has create_node function, creates two 3-input gate network. If the network has ternary create_maj and create_xor3 functions, it will use them (except for AIGs).

Parameters:

  • ntk – Network

  • a – First input operand

  • b – Second input operand

  • c – Carry

Returns:

Pair of sum (first) and carry (second)

template<typename Ntk>
inline void mockturtle::carry_ripple_adder_inplace(Ntk &ntk, std::vector<signal<Ntk>> &a, std::vector<signal<Ntk>> const &b, signal<Ntk> &carry)

Creates carry ripple adder structure.

Creates a carry ripple structure composed of full adders. The vectors a and b must have the same size. The resulting sum bits are eventually stored in a and the carry bit will be overridden to store the output carry bit.

Parameters:

  • a – First input operand, will also have the output after the call

  • b – Second input operand

  • carry – Carry bit, will also have the output carry after the call

template<typename Ntk>
inline void mockturtle::carry_ripple_subtractor_inplace(Ntk &ntk, std::vector<signal<Ntk>> &a, const std::vector<signal<Ntk>> &b, signal<Ntk> &carry)

Creates carry ripple subtractor structure.

Creates a carry ripple structure composed of full adders. The vectors a and b must have the same size. The resulting sum bits are eventually stored in a and the carry bit will be overridden to store the output carry bit. The inputs in b are inverted to realize subtraction with full adders. The carry bit must be passed in inverted state to the subtractor.

Parameters:

  • a – First input operand, will also have the output after the call

  • b – Second input operand

  • carry – Carry bit, will also have the output carry after the call

template<typename Ntk>
inline std::vector<signal<Ntk>> mockturtle::carry_ripple_multiplier(Ntk &ntk, std::vector<signal<Ntk>> const &a, std::vector<signal<Ntk>> const &b)

Creates a classical multiplier using full adders.

The vectors a and b must not have the same size. The function creates the multiplier in ntk and returns output signals, whose size is the summed sizes of a and b.

Parameters:

  • ntk – Network

  • a – First input operand

  • b – Second input operand

template<typename Ntk>
inline void mockturtle::carry_lookahead_adder_inplace(Ntk &ntk, std::vector<signal<Ntk>> &a, std::vector<signal<Ntk>> const &b, signal<Ntk> &carry)

Creates carry lookahead adder structure.

Creates a carry lookahead structure composed of full adders. The vectors a and b must have the same size. The resulting sum bits are eventually stored in a and the carry bit will be overridden to store the output carry bit.

Parameters:

  • a – First input operand, will also have the output after the call

  • b – Second input operand

  • carry – Carry bit, will also have the output carry after the call

template<typename Ntk>
inline std::vector<signal<Ntk>> mockturtle::sideways_sum_adder(Ntk &ntk, std::vector<signal<Ntk>> const &a)

Creates a sideways sum adder using half and full adders.

The function creates the adder in ntk and returns output signals, whose size is floor(log2(a.size()))+1.

Parameters:

  • ntk – Network

  • a – Input operand