Icard/angular-clarity-master(work.../node_modules/jszip/lib/crc32.js

78 lines
1.9 KiB
JavaScript

"use strict";
var utils = require("./utils");
/**
* The following functions come from pako, from pako/lib/zlib/crc32.js
* released under the MIT license, see pako https://github.com/nodeca/pako/
*/
// Use ordinary array, since untyped makes no boost here
function makeTable() {
var c, table = [];
for(var n =0; n < 256; n++){
c = n;
for(var k =0; k < 8; k++){
c = ((c&1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1));
}
table[n] = c;
}
return table;
}
// Create table on load. Just 255 signed longs. Not a problem.
var crcTable = makeTable();
function crc32(crc, buf, len, pos) {
var t = crcTable, end = pos + len;
crc = crc ^ (-1);
for (var i = pos; i < end; i++ ) {
crc = (crc >>> 8) ^ t[(crc ^ buf[i]) & 0xFF];
}
return (crc ^ (-1)); // >>> 0;
}
// That's all for the pako functions.
/**
* Compute the crc32 of a string.
* This is almost the same as the function crc32, but for strings. Using the
* same function for the two use cases leads to horrible performances.
* @param {Number} crc the starting value of the crc.
* @param {String} str the string to use.
* @param {Number} len the length of the string.
* @param {Number} pos the starting position for the crc32 computation.
* @return {Number} the computed crc32.
*/
function crc32str(crc, str, len, pos) {
var t = crcTable, end = pos + len;
crc = crc ^ (-1);
for (var i = pos; i < end; i++ ) {
crc = (crc >>> 8) ^ t[(crc ^ str.charCodeAt(i)) & 0xFF];
}
return (crc ^ (-1)); // >>> 0;
}
module.exports = function crc32wrapper(input, crc) {
if (typeof input === "undefined" || !input.length) {
return 0;
}
var isArray = utils.getTypeOf(input) !== "string";
if(isArray) {
return crc32(crc|0, input, input.length, 0);
} else {
return crc32str(crc|0, input, input.length, 0);
}
};