You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
29 lines
821 B
29 lines
821 B
var isStr = require('./isStr');
|
|
var strToBytes = require('./strToBytes');
|
|
var TABLE = [];
|
|
for (var n = 0; n < 256; n++) {
|
|
var c = n;
|
|
for (var k = 0; k < 8; k++) {
|
|
if (c & 1) {
|
|
c = 0xedb88320 ^ (c >>> 1);
|
|
} else {
|
|
c = c >>> 1;
|
|
}
|
|
}
|
|
TABLE[n] = c >>> 0;
|
|
}
|
|
if (typeof Int32Array !== 'undefined') TABLE = new Int32Array(TABLE);
|
|
exports = function(input, previous) {
|
|
return exports.signed(input, previous) >>> 0;
|
|
};
|
|
exports.signed = function(input, previous) {
|
|
if (isStr(input)) input = strToBytes(input);
|
|
var crc = previous === 0 ? 0 : ~~previous ^ -1;
|
|
for (var i = 0, len = input.length; i < len; i++) {
|
|
var byte = input[i];
|
|
crc = TABLE[(crc ^ byte) & 0xff] ^ (crc >>> 8);
|
|
}
|
|
return crc ^ -1;
|
|
};
|
|
|
|
module.exports = exports;
|
|
|