| 'use strict'; |
| |
| // Note: we can't get significant speed boost here. |
| // So write code to minimize size - no pregenerated tables |
| // and array tools dependencies. |
| |
| |
| // 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 ^= -1; |
| |
| for (var i = pos; i < end; i++) { |
| crc = (crc >>> 8) ^ t[(crc ^ buf[i]) & 0xFF]; |
| } |
| |
| return (crc ^ (-1)); // >>> 0; |
| } |
| |
| |
| module.exports = crc32; |