Bitshifting in Java.

[GastoGast]

Hallo!!
Ich möchte folgende PHP-Funktion auf Java umschreiben:

        function checksum ($url, $length = null, $init = 0xE6359A60) {
            if (is_null($length)) {
                $length = sizeof($url);
            }
            $a = $b = 0x9E3779B9;
            $c = $init;
            $k = 0;
            $len = $length;
            while($len >= 12) {
                $a += ($url[$k + 0] + ($url[$k + 1] << 8) + ($url[$k + 2] << 16) + ($url[$k +3] << 24));
                $b += ($url[$k + 4] + ($url[$k + 5] << 8) + ($url[$k + 6] << 16) + ($url[$k +7] << 24));
                $c += ($url[$k + 8] + ($url[$k + 9] << 8) + ($url[$k + 10] << 16) + ($url[$k +11] << 24));
                $mix = $this->mix($a, $b, $c);
                $a = $mix[0]; $b = $mix[1]; $c = $mix[2];
                $k += 12;
                $len -= 12;
            }
            $c += $length;
            switch($len) {
                case 11: $c += ($url[$k + 10] << 24);
                case 10: $c += ($url[$k + 9] << 16);
                case 9 : $c += ($url[$k + 8] << 8);
                case 8 : $b += ($url[$k + 7] << 24);
                case 7 : $b += ($url[$k + 6] << 16);
                case 6 : $b += ($url[$k + 5] << 8);
                case 5 : $b += ($url[$k + 4]);
                case 4 : $a += ($url[$k + 3] << 24);
                case 3 : $a += ($url[$k + 2] << 16);
                case 2 : $a += ($url[$k + 1] << 8);
                case 1 : $a += ($url[$k + 0]);
            }
            $mix = $this->mix($a, $b, $c);
            return $mix[2];
        }

Kann mir jemand da helfen und vlt nen Beispiel machen? ( ist natürlich auch super nett wenn du denn java code postest ^^)
Danke!

 

[MasterEvil]

Na das is doch schon fast mit Copy&Paste getan
Was man nicht kann ist Werte im Funktionskopf zu initialisieren, ansonsten ist so ziemlich alles gleich.

public class checksum {

	public char make(char[] url) { return make(url, url.length, 0xE6359A60); }
	public char make(char[] url, int length) { return make(url, length, 0xE6359A60); }
	public char make(char[] url, long init) { return make(url, url.length, init); }
	public char make(char[] url, int length, long init) {

        if (length==0) length = url.length;

        long a = 0x9E3779B9, b = 0x9E3779B9;
        long c = init;
        int k = 0;
        int len = length;
        char[] mix;
        while(len >= 12) {
            a += (url[k + 0] + (url[k + 1] << 8) + (url[k + 2] << 16) + (url[k +3] << 24));
            b += (url[k + 4] + (url[k + 5] << 8) + (url[k + 6] << 16) + (url[k +7] << 24));
            c += (url[k + 8] + (url[k + 9] << 8) + (url[k + 10] << 16) + (url[k +11] << 24));
            mix = mix(a, b, c);
            a = mix[0];
            b = mix[1];
            c = mix[2];
            k += 12;
            len -= 12;
        }
        c += length;
        switch(len) {
            case 11: c += (url[k + 10] << 24);
            case 10: c += (url[k + 9] << 16);
            case 9 : c += (url[k + 8] << 8);
            case 8 : b += (url[k + 7] << 24);
            case 7 : b += (url[k + 6] << 16);
            case 6 : b += (url[k + 5] << 8);
            case 5 : b += (url[k + 4]);
            case 4 : a += (url[k + 3] << 24);
            case 3 : a += (url[k + 2] << 16);
            case 2 : a += (url[k + 1] << 8);
            case 1 : a += (url[k + 0]);
        }
        mix = mix(a, b, c);
        return mix[2];
    }
	
	private char[] mix(long a, long b, long c) {
		// mix ?!?
		char[] mixed = new char[]{(char)c, (char)a, (char)b};

		return mixed;
	}
}

 

[Gast]

Wow Super
Und diese "mix" Funktion?

function mix ($a, $b, $c) {
            $a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c, 13)));
            $b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a << 8));
            $c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b, 13)));
            $a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c, 12)));
            $b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a << 16));
            $c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b, 5)));
            $a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c, 3)));
            $b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a << 10));
            $c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b, 15)));
            return array($a,$b,$c);
        }

 

[Gast]

Um Verwirrung vorzubeugen hier noch die beiden anderen Funktionen:

 function to_int_32 (&$x) {
            $z = hexdec(80000000);
            $y = (int) $x;
            if($y ==- $z && $x <- $z){
                $y = (int) ((-1) * $x);
                $y = (-1) * $y;
            }
            $x = $y;
        }
        
        function zero_fill ($a, $b) {
            $z = hexdec(80000000);
            if ($z & $a) {
                $a = ($a >> 1);
                $a &= (~$z);
                $a |= 0x40000000;
                $a = ($a >> ($b - 1));
            } else {
                $a = ($a >> $b);
            }
            return $a;
        }