Mercurial > public > cpp-enigma

annotate enigma/machine.h @ 13:b9d124a15926

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
To improve cache performance, the enigma machine rotors are now stored together with the reflector in a vector.
author Brian Neal <bgneal@gmail.com>
date Mon, 02 Jul 2012 19:14:36 -0500
parents 424111a36ed7
children 919b7a0d1802
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@11 19 typedef std::vector<std::shared_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@11 33 enigma_machine(const rotor_vector& rv,
bgneal@11 34 std::shared_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@11 38 enigma_machine(const rotor_vector& rv,
bgneal@11 39 std::shared_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@13 50 assert(rotors.size() == 4);
bgneal@4 51
bgneal@13 52 rotors[1].set_display(left);
bgneal@13 53 rotors[2].set_display(mid);
bgneal@13 54 rotors[3].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@13 60 assert(rotors.size() == 5);
bgneal@4 61
bgneal@13 62 rotors[1].set_display(c0);
bgneal@13 63 rotors[2].set_display(c1);
bgneal@13 64 rotors[3].set_display(c2);
bgneal@13 65 rotors[4].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@13 73 if (val.size() == 3 && rotors.size() == 4)
bgneal@7 74 {
bgneal@7 75 set_display(val[0], val[1], val[2]);
bgneal@7 76 }
bgneal@13 77 else if (val.size() == 4 && rotors.size() == 5)
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@13 91 for (std::size_t i = 1; i < rotors.size(); ++i)
bgneal@4 92 {
bgneal@13 93 result += rotors[i].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@12 126 // Process a buffer of pre-processed text of length n, placing the result in an output buffer.
bgneal@12 127 void process_data(const char* input, char* output, std::size_t n)
bgneal@12 128 {
bgneal@12 129 for (std::size_t i = 0; i < n; ++i)
bgneal@12 130 {
bgneal@12 131 step_rotors();
bgneal@12 132 *output++ = electric_signal(*input++) + 'A';
bgneal@12 133 }
bgneal@12 134 }
bgneal@12 135
bgneal@4 136 // for access to the plugboard for hill-climbing, etc
bgneal@4 137 plugboard& get_plugboard() { return pb; }
bgneal@4 138
bgneal@8 139 // Returns a string representation of the enigma machine's state. Useful
bgneal@8 140 // for logging, etc:
bgneal@8 141 //
bgneal@8 142 std::string army_str() const { return str(true); }
bgneal@8 143 std::string navy_str() const { return str(false); }
bgneal@8 144
bgneal@4 145 private:
bgneal@13 146 // Note that to improve cache performance, the rotors and reflectors are stored
bgneal@13 147 // in a contiguous vector.
bgneal@13 148 std::vector<rotor> rotors; // rotor & reflector array
bgneal@4 149 plugboard pb;
bgneal@4 150 rotor* r_rotor; // rightmost rotor
bgneal@4 151 rotor* m_rotor; // 2nd to right rotor
bgneal@4 152 rotor* l_rotor; // 3rd to right rotor
bgneal@4 153
bgneal@4 154 void rotor_count_check();
bgneal@4 155
bgneal@4 156 void step_rotors()
bgneal@4 157 {
bgneal@4 158 // The right-most rotor's right-side ratchet is always over a pawl, and
bgneal@4 159 // it has no neighbor to the right, so it always rotates.
bgneal@4 160 //
bgneal@4 161 // The middle rotor will rotate if either:
bgneal@4 162 // 1) The right-most rotor's left side notch is over the 2nd pawl
bgneal@4 163 // or
bgneal@4 164 // 2) It has a left-side notch over the 3rd pawl
bgneal@4 165 //
bgneal@4 166 // The third rotor (from the right) will rotate only if the middle rotor
bgneal@4 167 // has a left-side notch over the 3rd pawl.
bgneal@4 168 //
bgneal@4 169 // Kriegsmarine model M4 has 4 rotors, but the 4th rotor (the leftmost)
bgneal@4 170 // does not rotate (they did not add a 4th pawl to the mechanism).
bgneal@4 171
bgneal@4 172 const bool l_rotate = m_rotor->notch_over_pawl();
bgneal@4 173 const bool m_rotate = l_rotate || r_rotor->notch_over_pawl();
bgneal@4 174
bgneal@4 175 r_rotor->rotate();
bgneal@4 176 if (m_rotate)
bgneal@4 177 {
bgneal@4 178 m_rotor->rotate();
bgneal@4 179 }
bgneal@4 180 if (l_rotate)
bgneal@4 181 {
bgneal@4 182 l_rotor->rotate();
bgneal@4 183 }
bgneal@4 184 }
bgneal@4 185
bgneal@4 186 // Simulate running an electric signal through the machine in order to
bgneal@4 187 // perform an encrypt or decrypt operation
bgneal@4 188 // signal_num - the wire (0-25) that the simulated current occurs on
bgneal@4 189 // Returns a lamp number to light (an integer 0-25).
bgneal@4 190 int electric_signal(int signal_num)
bgneal@4 191 {
bgneal@13 192 int n = pb.signal(signal_num);
bgneal@4 193
bgneal@13 194 if (rotors.size() == 4) // 3 rotors + reflector
bgneal@4 195 {
bgneal@13 196 n = rotors[3].signal_in(n);
bgneal@13 197 n = rotors[2].signal_in(n);
bgneal@13 198 n = rotors[1].signal_in(n);
bgneal@13 199 n = rotors[0].signal_in(n); // reflector
bgneal@13 200 n = rotors[1].signal_out(n);
bgneal@13 201 n = rotors[2].signal_out(n);
bgneal@13 202 n = rotors[3].signal_out(n);
bgneal@4 203 }
bgneal@13 204 else // Kriegsmarine 4 rotor + reflector
bgneal@4 205 {
bgneal@13 206 n = rotors[4].signal_in(n);
bgneal@13 207 n = rotors[3].signal_in(n);
bgneal@13 208 n = rotors[2].signal_in(n);
bgneal@13 209 n = rotors[1].signal_in(n);
bgneal@13 210 n = rotors[0].signal_in(n); // reflector
bgneal@13 211 n = rotors[1].signal_out(n);
bgneal@13 212 n = rotors[2].signal_out(n);
bgneal@13 213 n = rotors[3].signal_out(n);
bgneal@13 214 n = rotors[4].signal_out(n);
bgneal@4 215 }
bgneal@13 216 return pb.signal(n);
bgneal@4 217 }
bgneal@8 218
bgneal@8 219 std::string str(bool army) const;
bgneal@4 220 };
bgneal@4 221 }
bgneal@4 222
bgneal@4 223 #endif