utf8BufferToUint16Array.js

function Utf8BufferToUint16Array(buff) {
    let c, char2, char3;
    let len = buff.length;
    let i = 0;
    let ni = 0;
    const newA = new Uint16Array(len);
    while (i < len) {
        c = buff[i++];
        if (c < 128) {
            newA[ni++] = c;
        } else if (c <= 224) {
            char2 = buff[i++];
            newA[ni++] = (c & 0x1F) << 6 | char2 & 0x3F;
        } else {
            char2 = buff[i++];
            char3 = buff[i++];
            newA[ni++] = (c & 0x0F) << 12 | (char2 & 0x3F) << 6 | (char3 & 0x3F) << 0;
        }
    }
    return newA;
}
// http://www.onicos.com/staff/iz/amuse/javascript/expert/utf.txt
// performance: 100x1mb ~ 260ms