Function to reverse the bits of a given integer

bit-reverse.js

function bitRev(N) {
    var r = 0;
        val = 0;

    while(N > 0) {
        val = N&1;
        N >>= 1;

        r += val&1;
        r <<= 1;
    }
    r >>= 1;

    return r;
}

function reverse(bits) {   
    var  x=new Uint32Array(1); x[0]=bits; 
    x[0] = ((x[0] & 0x0000ffff) << 16) | ((x[0] & 0xffff0000) >>> 16);
    x[0] = ((x[0] & 0x55555555) << 1) | ((x[0] & 0xAAAAAAAA) >>> 1);
    x[0] = ((x[0] & 0x33333333) << 2) | ((x[0] & 0xCCCCCCCC) >>> 2);
    x[0] = ((x[0] & 0x0F0F0F0F) << 4) | ((x[0] & 0xF0F0F0F0) >>> 4);
    x[0] = ((x[0] & 0x00FF00FF) << 8) | ((x[0] & 0xFF00FF00) >>> 8);
    return x[0];
}

no loops .. no sign bit problems ..