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Bombe: review, tests, validation

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s2224834 2019-01-08 18:25:42 +00:00
parent b6eb4e84e4
commit ad6e30f3d4
5 changed files with 173 additions and 31 deletions
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34
src/core/lib/Bombe.mjs
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@ -77,10 +77,7 @@ class Edge {
* @returns {number}
*/
getOther(node) {
if (this.node1 === node) {
return this.node2;
}
return this.node1;
return this.node1 === node ? this.node2 : this.node1;
}
}
@ -144,10 +141,7 @@ class Scrambler {
* @returns {number}
*/
getOtherEnd(end) {
if (this.end1 === end) {
return this.end2;
}
return this.end1;
return this.end1 === end ? this.end2 : this.end1;
}
/**
@ -194,8 +188,11 @@ export class BombeMachine {
* @param {function} update - Function to call to send status updates (optional)
*/
constructor(rotors, reflector, ciphertext, crib, update=undefined) {
if (ciphertext.length !== crib.length) {
throw new OperationError("Ciphertext and crib length differ");
if (ciphertext.length < crib.length) {
throw new OperationError("Crib overruns supplied ciphertext");
}
if (ciphertext.length > crib.length) {
throw new OperationError("Ciphertext is longer than crib");
}
if (crib.length < 2) {
// This is the absolute bare minimum to be sane, and even then it's likely too short to
@ -226,7 +223,7 @@ export class BombeMachine {
// This is the bundle of wires corresponding to the 26 letters within each of the 26
// possible nodes in the menu
this.wires = new Array(26*26).fill(false);
this.wires = new Array(26*26);
// These are the pseudo-Engima devices corresponding to each edge in the menu, and the
// nodes in the menu they each connect to
@ -271,9 +268,9 @@ export class BombeMachine {
* If we have a way of sending status messages, do so.
* @param {string} msg - Message to send.
*/
update(msg) {
update(...msg) {
if (this.updateFn !== undefined) {
this.updateFn(msg);
this.updateFn(...msg);
}
}
@ -411,7 +408,10 @@ export class BombeMachine {
// For each possible rotor setting
const nChecks = Math.pow(26, this.baseRotors.length);
for (let i=1; i<=nChecks; i++) {
this.wires.fill(false);
// Benchmarking suggests this is faster than using .fill()
for (let i=0; i<this.wires.length; i++) {
this.wires[i] = false;
}
// Energise the test input, follow the current through each scrambler
// (and the diagonal board)
this.energiseCount = 0;
@ -462,9 +462,9 @@ export class BombeMachine {
scrambler.step(n);
}
// Send status messages at what seems to be a reasonably sensible frequency
if (n > 2) {
const msg = `Bombe run with ${this.nLoops} loops in menu (2+ desirable): ${stops} stops, ${Math.floor(100 * i / nChecks)}% done`;
this.update(msg);
// (note this won't be triggered on 3-rotor runs - they run fast enough it doesn't seem necessary)
if (n > 3) {
this.update(this.nLoops, stops, i/nChecks);
}
}
return result;