162 lines
3.0 KiB
JavaScript
162 lines
3.0 KiB
JavaScript
/*!
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* common.js - mining utils
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* Copyright (c) 2014-2017, Christopher Jeffrey (MIT License).
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* https://github.com/bcoin-org/bcoin
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*/
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'use strict';
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var assert = require('assert');
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var consensus = require('../protocol/consensus');
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var BN = require('../crypto/bn');
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/**
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* @exports mining/common
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*/
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var common = exports;
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/*
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* Constants
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*/
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var DIFF = 0x00000000ffff0000000000000000000000000000000000000000000000000000;
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var B192 = 0x1000000000000000000000000000000000000000000000000;
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var B128 = 0x100000000000000000000000000000000;
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var B64 = 0x10000000000000000;
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var B0 = 0x1;
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/**
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* Swap 32 bit endianness of uint256.
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* @param {Buffer} data
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* @returns {Buffer}
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*/
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common.swap32 = function swap32(data) {
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var i, field;
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for (i = 0; i < data.length; i += 4) {
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field = data.readUInt32LE(i, true);
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data.writeUInt32BE(field, i, true);
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}
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return data;
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};
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/**
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* Swap 32 bit endianness of uint256 (hex).
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* @param {String} str
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* @returns {String}
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*/
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common.swap32hex = function swap32hex(str) {
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var data = Buffer.from(str, 'hex');
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return common.swap32(data).toString('hex');
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};
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/**
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* Compare two uint256le's.
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* @param {Buffer} a
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* @param {Buffer} b
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* @returns {Number}
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*/
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common.rcmp = function rcmp(a, b) {
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var i;
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assert(a.length === b.length);
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for (i = a.length - 1; i >= 0; i--) {
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if (a[i] < b[i])
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return -1;
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if (a[i] > b[i])
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return 1;
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}
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return 0;
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};
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/**
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* Convert a uint256le to a double.
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* @param {Buffer} target
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* @returns {Number}
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*/
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common.double256 = function double256(target) {
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var n = 0;
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var hi, lo;
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assert(target.length === 32);
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hi = target.readUInt32LE(28, true);
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lo = target.readUInt32LE(24, true);
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n += (hi * 0x100000000 + lo) * B192;
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hi = target.readUInt32LE(20, true);
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lo = target.readUInt32LE(16, true);
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n += (hi * 0x100000000 + lo) * B128;
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hi = target.readUInt32LE(12, true);
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lo = target.readUInt32LE(8, true);
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n += (hi * 0x100000000 + lo) * B64;
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hi = target.readUInt32LE(4, true);
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lo = target.readUInt32LE(0, true);
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n += (hi * 0x100000000 + lo) * B0;
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return n;
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};
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/**
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* Calculate mining difficulty
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* from little-endian target.
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* @param {Buffer} target
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* @returns {Number}
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*/
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common.getDifficulty = function getDifficulty(target) {
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var d = DIFF;
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var n = common.double256(target);
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if (n === 0)
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return d;
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if (n > d)
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return d;
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return Math.floor(d / n);
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};
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/**
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* Get target from bits as a uint256le.
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* @param {Number} bits
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* @returns {Buffer}
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*/
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common.getTarget = function getTarget(bits) {
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var target = consensus.fromCompact(bits);
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if (target.isNeg())
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throw new Error('Target is negative.');
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if (target.cmpn(0) === 0)
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throw new Error('Target is zero.');
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return target.toArrayLike(Buffer, 'le', 32);
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};
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/**
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* Get bits from target.
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* @param {Buffer} data
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* @returns {Buffer}
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*/
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common.getBits = function getBits(data) {
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var target = new BN(data, 'le');
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if (target.cmpn(0) === 0)
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throw new Error('Target is zero.');
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return consensus.toCompact(target);
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};
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