export default class Integer {
    public static MIN_VALUE_32_BITS = -2147483648;

    public static numberOfTrailingZeros(i: number): number {

        let y;

        if (i === 0) return 32;

        let n = 31;

        y = i << 16;

        if (y !== 0) {
            n -= 16;
            i = y;
        }

        y = i << 8;

        if (y !== 0) {
            n -= 8;
            i = y;
        }

        y = i << 4;

        if (y !== 0) {
            n -= 4;
            i = y;
        }

        y = i << 2;

        if (y !== 0) {
            n -= 2;
            i = y;
        }

        return n - ((i << 1) >>> 31);
    }

    public static numberOfLeadingZeros(i: number): number {

        // HD, Figure 5-6
        if (i === 0) {
            return 32;
        }

        let n = 1;

        if (i >>> 16 === 0) {
            n += 16;
            i <<= 16;
        }

        if (i >>> 24 === 0) {
            n += 8;
            i <<= 8;
        }

        if (i >>> 28 === 0) {
            n += 4;
            i <<= 4;
        }

        if (i >>> 30 === 0) {
            n += 2;
            i <<= 2;
        }

        n -= i >>> 31;

        return n;
    }

    public static toHexString(i: number) {
        return i.toString(16);
    }

    // Returns the number of one-bits in the two's complement binary representation of the specified int value. This function is sometimes referred to as the population count.
    // Returns:
    // the number of one-bits in the two's complement binary representation of the specified int value.
    public static bitCount(i: number): number {
        // HD, Figure 5-2
        i = i - ((i >>> 1) & 0x55555555);
        i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
        i = (i + (i >>> 4)) & 0x0f0f0f0f;
        i = i + (i >>> 8);
        i = i + (i >>> 16);

        return i & 0x3f;
    }
}