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annotate enigma/machine.h @ 7:db1216d380b3

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Added a set_rotor() that takes a string for convenience.
author Brian Neal <bgneal@gmail.com>
date Fri, 29 Jun 2012 20:08:10 -0500
parents 2792ca4ffa84
children b90a41f0cd94
rev   line source
bgneal@4 1 #ifndef CPP_ENIGMA_MACHINE_H
bgneal@4 2 #define CPP_ENIGMA_MACHINE_H
bgneal@4 3 // Copyright (C) 2012 by Brian Neal.
bgneal@4 4 // This file is part of Cpp-Enigma, the Enigma Machine simulation.
bgneal@4 5 // Cpp-Enigma is released under the MIT License (see License.txt).
bgneal@4 6 //
bgneal@4 7 // machine.h - This file contains the main Enigma machine class.
bgneal@4 8
bgneal@4 9 #include <memory>
bgneal@4 10 #include <string>
bgneal@4 11 #include <vector>
bgneal@4 12 #include <cassert>
bgneal@4 13 #include "enigma_types.h"
bgneal@4 14 #include "rotor.h"
bgneal@4 15 #include "plugboard.h"
bgneal@4 16
bgneal@4 17 namespace enigma
bgneal@4 18 {
bgneal@4 19 typedef std::vector<std::unique_ptr<rotor>> rotor_vector;
bgneal@4 20
bgneal@4 21 class enigma_machine_error : public enigma_error
bgneal@4 22 {
bgneal@4 23 public:
bgneal@4 24 explicit enigma_machine_error(const std::string& what_arg)
bgneal@4 25 : enigma_error(what_arg)
bgneal@4 26 {}
bgneal@4 27 };
bgneal@4 28
bgneal@4 29 class enigma_machine
bgneal@4 30 {
bgneal@4 31 public:
bgneal@4 32 // construct an Enigma machine from component parts:
bgneal@4 33 enigma_machine(rotor_vector rv,
bgneal@4 34 std::unique_ptr<rotor> reflector,
bgneal@4 35 const plugboard& pb);
bgneal@4 36
bgneal@4 37 // construct an Enigma machine with a default plugboard (no cables connected):
bgneal@4 38 enigma_machine(rotor_vector rv,
bgneal@4 39 std::unique_ptr<rotor> reflector);
bgneal@4 40
bgneal@4 41 // key-sheet style constructors:
bgneal@4 42 enigma_machine(const std::vector<std::string>& rotor_types,
bgneal@4 43 const std::vector<int>& ring_settings,
bgneal@4 44 const std::string& reflector_name = "B",
bgneal@4 45 const std::string& plugboard_settings = "");
bgneal@4 46
bgneal@4 47 // set the rotor display (starting position) - 3 rotor version
bgneal@4 48 void set_display(char left, char mid, char right)
bgneal@4 49 {
bgneal@4 50 assert(rotors.size() == 3);
bgneal@4 51
bgneal@4 52 rotors[0]->set_display(left);
bgneal@4 53 rotors[1]->set_display(mid);
bgneal@4 54 rotors[2]->set_display(right);
bgneal@4 55 }
bgneal@4 56
bgneal@4 57 // set the rotor display (starting position) - 4 rotor version
bgneal@4 58 void set_display(char c0, char c1, char c2, char c3)
bgneal@4 59 {
bgneal@4 60 assert(rotors.size() == 4);
bgneal@4 61
bgneal@4 62 rotors[0]->set_display(c0);
bgneal@4 63 rotors[1]->set_display(c1);
bgneal@4 64 rotors[2]->set_display(c2);
bgneal@4 65 rotors[3]->set_display(c3);
bgneal@4 66 }
bgneal@4 67
bgneal@7 68 // Set the rotor display (starting position) using a string; the
bgneal@7 69 // string length must match the number of rotors in use or a
bgneal@7 70 // enigma_machine_error exception will be thrown:
bgneal@7 71 void set_display(const std::string& val)
bgneal@7 72 {
bgneal@7 73 if (val.size() == 3 && rotors.size() == 3)
bgneal@7 74 {
bgneal@7 75 set_display(val[0], val[1], val[2]);
bgneal@7 76 }
bgneal@7 77 else if (val.size() == 4 && rotors.size() == 4)
bgneal@7 78 {
bgneal@7 79 set_display(val[0], val[1], val[2], val[3]);
bgneal@7 80 }
bgneal@7 81 else
bgneal@7 82 {
bgneal@7 83 throw enigma_machine_error("set_display invalid size");
bgneal@7 84 }
bgneal@7 85 }
bgneal@7 86
bgneal@4 87 // return the rotor display (starting position) as a string
bgneal@4 88 std::string get_display() const
bgneal@4 89 {
bgneal@4 90 std::string result;
bgneal@4 91 for (const auto& r : rotors)
bgneal@4 92 {
bgneal@4 93 result += r->get_display();
bgneal@4 94 }
bgneal@4 95 return result;
bgneal@4 96 }
bgneal@4 97
bgneal@4 98 // simulate front panel key press; returns the lamp character that is lit
bgneal@4 99 char key_press(char c)
bgneal@4 100 {
bgneal@4 101 step_rotors();
bgneal@4 102 return electric_signal(c - 'A') + 'A';
bgneal@4 103 }
bgneal@4 104
bgneal@4 105 // Process a buffer of text of length n, placing the result in an output buffer.
bgneal@4 106 void process_text(const char* input, char* output, std::size_t n)
bgneal@4 107 {
bgneal@4 108 for (std::size_t i = 0; i < n; ++i)
bgneal@4 109 {
bgneal@4 110 *output++ = key_press(*input++);
bgneal@4 111 }
bgneal@4 112 }
bgneal@4 113
bgneal@4 114 std::string process_text(const std::string& input)
bgneal@4 115 {
bgneal@4 116 std::string result;
bgneal@4 117 result.reserve(input.size());
bgneal@4 118
bgneal@4 119 for (const auto& c : input)
bgneal@4 120 {
bgneal@4 121 result += key_press(c);
bgneal@4 122 }
bgneal@4 123 return result;
bgneal@4 124 }
bgneal@4 125
bgneal@4 126 // for access to the plugboard for hill-climbing, etc
bgneal@4 127 plugboard& get_plugboard() { return pb; }
bgneal@4 128
bgneal@4 129 private:
bgneal@4 130 rotor_vector rotors;
bgneal@4 131 std::unique_ptr<rotor> reflector;
bgneal@4 132 plugboard pb;
bgneal@4 133 rotor* r_rotor; // rightmost rotor
bgneal@4 134 rotor* m_rotor; // 2nd to right rotor
bgneal@4 135 rotor* l_rotor; // 3rd to right rotor
bgneal@4 136
bgneal@4 137 void rotor_count_check();
bgneal@4 138
bgneal@4 139 void step_rotors()
bgneal@4 140 {
bgneal@4 141 // The right-most rotor's right-side ratchet is always over a pawl, and
bgneal@4 142 // it has no neighbor to the right, so it always rotates.
bgneal@4 143 //
bgneal@4 144 // The middle rotor will rotate if either:
bgneal@4 145 // 1) The right-most rotor's left side notch is over the 2nd pawl
bgneal@4 146 // or
bgneal@4 147 // 2) It has a left-side notch over the 3rd pawl
bgneal@4 148 //
bgneal@4 149 // The third rotor (from the right) will rotate only if the middle rotor
bgneal@4 150 // has a left-side notch over the 3rd pawl.
bgneal@4 151 //
bgneal@4 152 // Kriegsmarine model M4 has 4 rotors, but the 4th rotor (the leftmost)
bgneal@4 153 // does not rotate (they did not add a 4th pawl to the mechanism).
bgneal@4 154
bgneal@4 155 const bool l_rotate = m_rotor->notch_over_pawl();
bgneal@4 156 const bool m_rotate = l_rotate || r_rotor->notch_over_pawl();
bgneal@4 157
bgneal@4 158 r_rotor->rotate();
bgneal@4 159 if (m_rotate)
bgneal@4 160 {
bgneal@4 161 m_rotor->rotate();
bgneal@4 162 }
bgneal@4 163 if (l_rotate)
bgneal@4 164 {
bgneal@4 165 l_rotor->rotate();
bgneal@4 166 }
bgneal@4 167 }
bgneal@4 168
bgneal@4 169 // Simulate running an electric signal through the machine in order to
bgneal@4 170 // perform an encrypt or decrypt operation
bgneal@4 171 // signal_num - the wire (0-25) that the simulated current occurs on
bgneal@4 172 // Returns a lamp number to light (an integer 0-25).
bgneal@4 173 int electric_signal(int signal_num)
bgneal@4 174 {
bgneal@4 175 int pos = pb.signal(signal_num);
bgneal@4 176
bgneal@4 177 for (auto r = rotors.rbegin(); r != rotors.rend(); ++r)
bgneal@4 178 {
bgneal@4 179 pos = (*r)->signal_in(pos);
bgneal@4 180 }
bgneal@4 181
bgneal@4 182 pos = reflector->signal_in(pos);
bgneal@4 183
bgneal@4 184 for (const auto& r : rotors)
bgneal@4 185 {
bgneal@4 186 pos = r->signal_out(pos);
bgneal@4 187 }
bgneal@4 188
bgneal@4 189 return pb.signal(pos);
bgneal@4 190 }
bgneal@4 191 };
bgneal@4 192 }
bgneal@4 193
bgneal@4 194 #endif