//copy from ../module/rangy-serializer
//rangy1 export crc32 as a member of util

// Checksum for checking whether range can be serialized

        function utf8encode(str) {
            var utf8CharCodes = [];

            for (var i = 0, len = str.length, c; i < len; ++i) {
                c = str.charCodeAt(i);
                if (c < 128) {
                    utf8CharCodes.push(c);
                } else if (c < 2048) {
                    utf8CharCodes.push((c >> 6) | 192, (c & 63) | 128);
                } else {
                    utf8CharCodes.push((c >> 12) | 224, ((c >> 6) & 63) | 128, (c & 63) | 128);
                }
            }
            return utf8CharCodes;
        }

        var cachedCrcTable = null;

        function buildCRCTable() {
            var table = [];
            for (var i = 0, j, crc; i < 256; ++i) {
                crc = i;
                j = 8;
                while (j--) {
                    if ((crc & 1) == 1) {
                        crc = (crc >>> 1) ^ 0xEDB88320;
                    } else {
                        crc >>>= 1;
                    }
                }
                table[i] = crc >>> 0;
            }
            return table;
        }

        function getCrcTable() {
            if (!cachedCrcTable) {
                cachedCrcTable = buildCRCTable();
            }
            return cachedCrcTable;
        }

        export function crc32(str) {
            var utf8CharCodes = utf8encode(str), crc = -1, crcTable = getCrcTable();
            for (var i = 0, len = utf8CharCodes.length, y; i < len; ++i) {
                y = (crc ^ utf8CharCodes[i]) & 0xFF;
                crc = (crc >>> 8) ^ crcTable[y];
            }
            return (crc ^ -1) >>> 0;
        }