66 lines
1.9 KiB
JavaScript
66 lines
1.9 KiB
JavaScript
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/**
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* Web Worker routines for Browser platform.
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*/
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"use strict";
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// NOTE(Kagami): In order to use it you need to create separate
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// browserify bundle for this file, place it somewhere in your HTTP
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// server assets path (under the same origin with your application code)
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// and then pass appropriate `workerUrl` value to the function that
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// spawns workers.
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// You may also try to pass object URL instead. See
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// <http://mdn.io/worker.worker>, <https://stackoverflow.com/q/10343913>
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// for details.
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// XXX(Kagami): This is rather unpleasent that we use different SHA-2
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// implementations for main library code and for worker code (we use
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// `sha.js` here because it's faster). Though worker code lays in
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// separate file so it shouldn't result in any download overhead.
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var createHash = require("sha.js");
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function sha512(buf) {
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return createHash("sha512").update(buf).digest();
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}
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function pow(opts) {
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var nonce = opts.num;
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var poolSize = opts.poolSize;
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var message = new Buffer(72);
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message.fill(0);
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Buffer(opts.initialHash).copy(message, 8);
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var targetHi = Math.floor(opts.target / 4294967296);
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var targetLo = opts.target % 4294967296;
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var digest, trialHi, trialLo;
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while (true) {
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// uint32_t overflow. There is no much need to fix it since 4G
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// double hashes would we computed too long anyway in a Browser.
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if (nonce > 4294967295) {
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return -1;
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}
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message.writeUInt32BE(nonce, 4, true);
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digest = sha512(sha512(message));
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trialHi = digest.readUInt32BE(0, true);
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if (trialHi > targetHi) {
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nonce += poolSize;
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} else if (trialHi === targetHi) {
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trialLo = digest.readUInt32BE(4, true);
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if (trialLo > targetLo) {
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nonce += poolSize;
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} else {
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return nonce;
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}
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} else {
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return nonce;
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}
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}
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}
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onmessage = function(e) { // jshint ignore:line
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var nonce = pow(e.data);
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postMessage(nonce); // jshint ignore:line
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};
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