bgneal@4: #ifndef CPP_ENIGMA_MACHINE_H
bgneal@4: #define CPP_ENIGMA_MACHINE_H
bgneal@4: // Copyright (C) 2012 by Brian Neal.
bgneal@4: // This file is part of Cpp-Enigma, the Enigma Machine simulation.
bgneal@4: // Cpp-Enigma is released under the MIT License (see License.txt).
bgneal@4: //
bgneal@4: // machine.h - This file contains the main Enigma machine class.
bgneal@4: 
bgneal@4: #include <memory>
bgneal@4: #include <string>
bgneal@4: #include <vector>
bgneal@4: #include <cassert>
bgneal@4: #include "enigma_types.h"
bgneal@4: #include "rotor.h"
bgneal@4: #include "plugboard.h"
bgneal@4: 
bgneal@4: namespace enigma
bgneal@4: {
bgneal@4:    typedef std::vector<std::unique_ptr<rotor>> rotor_vector;
bgneal@4: 
bgneal@4:    class enigma_machine_error : public enigma_error
bgneal@4:    {
bgneal@4:    public:
bgneal@4:       explicit enigma_machine_error(const std::string& what_arg)
bgneal@4:        : enigma_error(what_arg)
bgneal@4:       {}
bgneal@4:    };
bgneal@4: 
bgneal@4:    class enigma_machine
bgneal@4:    {
bgneal@4:    public:
bgneal@4:       // construct an Enigma machine from component parts:
bgneal@4:       enigma_machine(rotor_vector rv,
bgneal@4:                      std::unique_ptr<rotor> reflector,
bgneal@4:                      const plugboard& pb);
bgneal@4: 
bgneal@4:       // construct an Enigma machine with a default plugboard (no cables connected):
bgneal@4:       enigma_machine(rotor_vector rv,
bgneal@4:                      std::unique_ptr<rotor> reflector);
bgneal@4: 
bgneal@4:       // key-sheet style constructors:
bgneal@4:       enigma_machine(const std::vector<std::string>& rotor_types,
bgneal@4:                      const std::vector<int>& ring_settings,
bgneal@4:                      const std::string& reflector_name = "B",
bgneal@4:                      const std::string& plugboard_settings = "");
bgneal@4: 
bgneal@4:       // set the rotor display (starting position) - 3 rotor version
bgneal@4:       void set_display(char left, char mid, char right)
bgneal@4:       {
bgneal@4:          assert(rotors.size() == 3);
bgneal@4: 
bgneal@4:          rotors[0]->set_display(left);
bgneal@4:          rotors[1]->set_display(mid);
bgneal@4:          rotors[2]->set_display(right);
bgneal@4:       }
bgneal@4: 
bgneal@4:       // set the rotor display (starting position) - 4 rotor version
bgneal@4:       void set_display(char c0, char c1, char c2, char c3)
bgneal@4:       {
bgneal@4:          assert(rotors.size() == 4);
bgneal@4: 
bgneal@4:          rotors[0]->set_display(c0);
bgneal@4:          rotors[1]->set_display(c1);
bgneal@4:          rotors[2]->set_display(c2);
bgneal@4:          rotors[3]->set_display(c3);
bgneal@4:       }
bgneal@4: 
bgneal@4:       // return the rotor display (starting position) as a string
bgneal@4:       std::string get_display() const
bgneal@4:       {
bgneal@4:          std::string result;
bgneal@4:          for (const auto& r : rotors)
bgneal@4:          {
bgneal@4:             result += r->get_display();
bgneal@4:          }
bgneal@4:          return result;
bgneal@4:       }
bgneal@4: 
bgneal@4:       // simulate front panel key press; returns the lamp character that is lit
bgneal@4:       char key_press(char c)
bgneal@4:       {
bgneal@4:          step_rotors();
bgneal@4:          return electric_signal(c - 'A') + 'A';
bgneal@4:       }
bgneal@4: 
bgneal@4:       // Process a buffer of text of length n, placing the result in an output buffer.
bgneal@4:       void process_text(const char* input, char* output, std::size_t n)
bgneal@4:       {
bgneal@4:          for (std::size_t i = 0; i < n; ++i)
bgneal@4:          {
bgneal@4:             *output++ = key_press(*input++);
bgneal@4:          }
bgneal@4:       }
bgneal@4: 
bgneal@4:       std::string process_text(const std::string& input)
bgneal@4:       {
bgneal@4:          std::string result;
bgneal@4:          result.reserve(input.size());
bgneal@4: 
bgneal@4:          for (const auto& c : input)
bgneal@4:          {
bgneal@4:             result += key_press(c);
bgneal@4:          }
bgneal@4:          return result;
bgneal@4:       }
bgneal@4: 
bgneal@4:       // for access to the plugboard for hill-climbing, etc
bgneal@4:       plugboard& get_plugboard() { return pb; }
bgneal@4: 
bgneal@4:    private:
bgneal@4:       rotor_vector rotors;
bgneal@4:       std::unique_ptr<rotor> reflector;
bgneal@4:       plugboard pb;
bgneal@4:       rotor* r_rotor;      // rightmost rotor
bgneal@4:       rotor* m_rotor;      // 2nd to right rotor
bgneal@4:       rotor* l_rotor;      // 3rd to right rotor
bgneal@4: 
bgneal@4:       void rotor_count_check();
bgneal@4: 
bgneal@4:       void step_rotors()
bgneal@4:       {
bgneal@4:          // The right-most rotor's right-side ratchet is always over a pawl, and
bgneal@4:          // it has no neighbor to the right, so it always rotates.
bgneal@4:          //
bgneal@4:          // The middle rotor will rotate if either:
bgneal@4:          //   1) The right-most rotor's left side notch is over the 2nd pawl
bgneal@4:          //       or
bgneal@4:          //   2) It has a left-side notch over the 3rd pawl
bgneal@4:          //
bgneal@4:          // The third rotor (from the right) will rotate only if the middle rotor
bgneal@4:          // has a left-side notch over the 3rd pawl.
bgneal@4:          //
bgneal@4:          // Kriegsmarine model M4 has 4 rotors, but the 4th rotor (the leftmost)
bgneal@4:          // does not rotate (they did not add a 4th pawl to the mechanism).
bgneal@4: 
bgneal@4:          const bool l_rotate = m_rotor->notch_over_pawl();
bgneal@4:          const bool m_rotate = l_rotate || r_rotor->notch_over_pawl();
bgneal@4: 
bgneal@4:          r_rotor->rotate();
bgneal@4:          if (m_rotate)
bgneal@4:          {
bgneal@4:             m_rotor->rotate();
bgneal@4:          }
bgneal@4:          if (l_rotate)
bgneal@4:          {
bgneal@4:             l_rotor->rotate();
bgneal@4:          }
bgneal@4:       }
bgneal@4: 
bgneal@4:       // Simulate running an electric signal through the machine in order to
bgneal@4:       // perform an encrypt or decrypt operation
bgneal@4:       // signal_num - the wire (0-25) that the simulated current occurs on
bgneal@4:       // Returns a lamp number to light (an integer 0-25).
bgneal@4:       int electric_signal(int signal_num)
bgneal@4:       {
bgneal@4:          int pos = pb.signal(signal_num);
bgneal@4: 
bgneal@4:          for (auto r = rotors.rbegin(); r != rotors.rend(); ++r)
bgneal@4:          {
bgneal@4:             pos = (*r)->signal_in(pos);
bgneal@4:          }
bgneal@4: 
bgneal@4:          pos = reflector->signal_in(pos);
bgneal@4: 
bgneal@4:          for (const auto& r : rotors)
bgneal@4:          {
bgneal@4:             pos = r->signal_out(pos);
bgneal@4:          }
bgneal@4: 
bgneal@4:          return pb.signal(pos);
bgneal@4:       }
bgneal@4:    };
bgneal@4: }
bgneal@4: 
bgneal@4: #endif