watch-xdelta/lib/util.js

smart-watch xdelta script

/**
 * Created by iyww on 15/9/15.
 */
'use strict';

var _regeneratorRuntime = require('babel-runtime/regenerator')['default'];

var _interopRequireDefault = require('babel-runtime/helpers/interop-require-default')['default'];

Object.defineProperty(exports, '__esModule', {
  value: true
});

var _co = require('co');

var _co2 = _interopRequireDefault(_co);

var _babelFs = require('babel-fs');

var _babelFs2 = _interopRequireDefault(_babelFs);

/**
 * 生成校验和的低16位
 * @param {Number} 校验和
 * @return {Object.highHex} 校验和高字节
 * @return {Object.lowHex} 校验和低字节
 *
 */
var checkSumToHex = function checkSumToHex(num) {
  var hexStr = num.toString(16);
  var highHex = parseInt(hexStr.slice(-4, -2), 16);
  var lowHex = parseInt(hexStr.slice(-2), 16);
  return { highHex: highHex, lowHex: lowHex };
};

exports.checkSumToHex = checkSumToHex;
/**
 * 截取文件最后32个字节
 * @param {String} filename 文件名称
 * @return {Object} 返回的对象中包含32字节tail,以及截去tail的新文件名称
 *
 */
var truncateLast32Bits = _co2['default'].wrap(_regeneratorRuntime.mark(function callee$0$0(filename) {
  var buffer, tempFile;
  return _regeneratorRuntime.wrap(function callee$0$0$(context$1$0) {
    while (1) switch (context$1$0.prev = context$1$0.next) {
      case 0:
        context$1$0.next = 2;
        return _babelFs2['default'].readFile(filename);

      case 2:
        buffer = context$1$0.sent;
        tempFile = filename + '.temp';
        context$1$0.next = 6;
        return _babelFs2['default'].writeFile(tempFile, buffer.slice(0, -32));

      case 6:
        return context$1$0.abrupt('return', { tail: buffer.slice(-32), tempFile: tempFile });

      case 7:
      case 'end':
        return context$1$0.stop();
    }
  }, callee$0$0, this);
}));
exports.truncateLast32Bits = truncateLast32Bits;