#include <stdio.h>

#define STRSTR( x ) #x
#define STR( x ) STRSTR( x )

#define PnX(x)                                          \
for ( ;; )                                              \
{                                                       \
    fprintf (stderr, "x: %-56s res: ", STR ( x; ));     \
    x;                                                  \
    break;                                              \
}

volatile int a = 0x55aa55aa;
volatile int b = 0xff00ff00;

int main ( int argc, char** argv )
{
    int c;

    fprintf ( stderr, "   %-61s a: 0x%08x b: 0x%08x\n", "--init--", a, b );

    PnX (a ^= ( b^= ( a ^= b )));

    fprintf ( stderr, "a: 0x%08x b: 0x%08x\n", a, b );

    /**
     * volatile weg-gecastet (nützt im Assembler nix, schad' aber auch nix)
     */

    PnX (((int) a ) ^= (((int) b )^= (((int) a ) ^= ((int) b ))));

    fprintf ( stderr, "a: 0x%08x b: 0x%08x\n", a, b );

    /**
     * volatile weg-gecastet (aber jetzt nützt's was)
     */

    {
        int c = a;
        int d = b;

        PnX (c ^= ( d^= ( c ^= d )));

        a = c;
        b = d;
    }

    fprintf ( stderr, "a: 0x%08x b: 0x%08x\n", a, b );

    PnX (a ^= b; b ^= a; a ^= b);

    fprintf ( stderr, "a: 0x%08x b: 0x%08x\n", a, b );

    PnX (c = a; a = b; b = c);

    fprintf ( stderr, "a: 0x%08x b: 0x%08x\n", a, b );

    PnX (b = ( a ^ b ) ^ ( a = b ));

    fprintf ( stderr, "a: 0x%08x b: 0x%08x\n", a, b );

    PnX (b = ( a = b ) ^ ( a ^ b ));

    fprintf ( stderr, "a: 0x%08x b: 0x%08x\n", a, b );

    exit ( 0 );
}