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// ethash.js
// Tim Hughes <tim@twistedfury.com>
// Revision 19
/*jslint node: true, shadow:true */
"use strict";
var Keccak = require('./keccak');
var util = require('./util');
var ethUtil = require('ethereumjs-util');
// 32-bit unsigned modulo
function mod32(x, n) {
return (x >>> 0) % (n >>> 0);
}
function fnv(x, y) {
// js integer multiply by 0x01000193 will lose precision
return ((x * 0x01000000 | 0) + (x * 0x193 | 0)) ^ y;
}
function computeCache(params, seedWords) {
var cache = new Uint32Array(params.cacheSize >> 2);
var cacheNodeCount = params.cacheSize >> 6;
// Initialize cache
var keccak = new Keccak();
keccak.digestWords(cache, 0, 16, seedWords, 0, seedWords.length);
for (var n = 1; n < cacheNodeCount; ++n) {
keccak.digestWords(cache, n << 4, 16, cache, (n - 1) << 4, 16);
}
var tmp = new Uint32Array(16);
// Do randmemohash passes
for (var r = 0; r < params.cacheRounds; ++r) {
for (var n = 0; n < cacheNodeCount; ++n) {
var p0 = mod32(n + cacheNodeCount - 1, cacheNodeCount) << 4;
var p1 = mod32(cache[n << 4 | 0], cacheNodeCount) << 4;
for (var w = 0; w < 16; w = (w + 1) | 0) {
tmp[w] = cache[p0 | w] ^ cache[p1 | w];
}
keccak.digestWords(cache, n << 4, 16, tmp, 0, tmp.length);
}
}
return cache;
}
function computeDagNode(o_node, params, cache, keccak, nodeIndex) {
var cacheNodeCount = params.cacheSize >> 6;
var dagParents = params.dagParents;
var c = (nodeIndex % cacheNodeCount) << 4;
var mix = o_node;
for (var w = 0; w < 16; ++w) {
mix[w] = cache[c | w];
}
mix[0] ^= nodeIndex;
keccak.digestWords(mix, 0, 16, mix, 0, 16);
for (var p = 0; p < dagParents; ++p) {
// compute cache node (word) index
c = mod32(fnv(nodeIndex ^ p, mix[p & 15]), cacheNodeCount) << 4;
for (var w = 0; w < 16; ++w) {
mix[w] = fnv(mix[w], cache[c | w]);
}
}
keccak.digestWords(mix, 0, 16, mix, 0, 16);
}
function computeHashInner(mix, params, cache, keccak, tempNode) {
var mixParents = params.mixParents | 0;
var mixWordCount = params.mixSize >> 2;
var mixNodeCount = mixWordCount >> 4;
var dagPageCount = (params.dagSize / params.mixSize) >> 0;
// grab initial first word
var s0 = mix[0];
// initialise mix from initial 64 bytes
for (var w = 16; w < mixWordCount; ++w) {
mix[w] = mix[w & 15];
}
for (var a = 0; a < mixParents; ++a) {
var p = mod32(fnv(s0 ^ a, mix[a & (mixWordCount - 1)]), dagPageCount);
var d = (p * mixNodeCount) | 0;
for (var n = 0, w = 0; n < mixNodeCount; ++n, w += 16) {
computeDagNode(tempNode, params, cache, keccak, (d + n) | 0);
for (var v = 0; v < 16; ++v) {
mix[w | v] = fnv(mix[w | v], tempNode[v]);
}
}
}
}
function convertSeed(seed) {
// todo, reconcile with spec, byte ordering?
// todo, big-endian conversion
var newSeed = util.toWords(seed);
if (newSeed === null)
throw Error("Invalid seed '" + seed + "'");
return newSeed;
}
var params = exports.params = {
REVISION: 23,
DATASET_BYTES_INIT: 1073741824,
DATASET_BYTES_GROWTH: 8388608,
CACHE_BYTES_INIT: 1073741824,
CACHE_BYTES_GROWTH: 131072,
EPOCH_LENGTH: 30000,
MIX_BYTES: 128,
HASH_BYTES: 64,
DATASET_PARENTS: 256,
CACHE_ROUNDS: 3,
ACCESSES: 64
};
var cache_sizes = require('./cache_sizes');
var dag_sizes = require('./dag_sizes');
exports.calcSeed = function(blockNum) {
var epoch;
var seed = new Uint8Array(32);
if (blockNum > cache_sizes.length * params.EPOCH_LENGTH) {
return new Error('Time to upgrade to POS!!!');
} else {
epoch = Math.floor(blockNum / params.EPOCH_LENGTH);
for (var i = 0; i < epoch; i++) {
seed = ethUtil.sha3(new Buffer(seed));
}
return seed;
}
};
exports.defaultParams = function() {
return {
cacheSize: 1048384,
cacheRounds: 3,
dagSize: 1073739904,
dagParents: 256,
mixSize: 128,
mixParents: 64
};
};
exports.Ethash = function(params, seed) {
// precompute cache and related values
// seed = convertSeed(seed);
var cache = computeCache(params, seed);
// preallocate buffers/etc
var initBuf = new ArrayBuffer(96);
var initBytes = new Uint8Array(initBuf);
var initWords = new Uint32Array(initBuf);
var mixWords = new Uint32Array(params.mixSize / 4);
var tempNode = new Uint32Array(16);
var keccak = new Keccak();
var retWords = new Uint32Array(8);
var retBytes = new Uint8Array(retWords.buffer); // supposedly read-only
this.hash = function(header, nonce) {
// compute initial hash
initBytes.set(header, 0);
initBytes.set(nonce, 32);
keccak.digestWords(initWords, 0, 16, initWords, 0, 8 + nonce.length / 4);
// compute mix
for (var i = 0; i !== 16; ++i) {
mixWords[i] = initWords[i];
}
computeHashInner(mixWords, params, cache, keccak, tempNode);
// compress mix and append to initWords
for (var i = 0; i !== mixWords.length; i += 4) {
initWords[16 + i / 4] = fnv(fnv(fnv(mixWords[i], mixWords[i + 1]), mixWords[i + 2]), mixWords[i + 3]);
}
// final Keccak hashes
keccak.digestWords(retWords, 0, 8, initWords, 0, 24); // Keccak-256(s + cmix)
return retBytes;
};
this.cacheDigest = function() {
return keccak.digest(32, new Uint8Array(cache.buffer));
};
};
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