XXTEA算法的C语言实现

#define DELTA 0x9e3779b9
#define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (key[(p&3)^e] ^ z)))
#define XXTEA_ENCODE_MODE 0
#define XXTEA_DECODE_MODE 1

void xxtea(unsigned int *v, int n, const unsigned int key[], int mode)
{
    unsigned int y, z, sum;
    unsigned int p, rounds, e;

	if(n <= 1) return;
    if(mode == XXTEA_ENCODE_MODE) {          /* Coding Part */
        rounds = 6 + 52/n;
        sum = 0;
        z = v[n - 1];
        do {
            sum += DELTA;
            e = (sum >> 2) & 3;
            for(p = 0; p < n - 1; p++) {
                y = v[p + 1]; 
                z = v[p] += MX;
            }
            y = v[0];
            z = v[n - 1] += MX;
        }while(--rounds);
    } else if(mode == XXTEA_DECODE_MODE) {   /* Decoding Part */
        rounds = 6 + 52/n;
        sum = rounds * DELTA;
        y = v[0];
        do {
            e = (sum >> 2) & 3;
            for(p = n - 1; p > 0; p--) {
                z = v[p - 1];
                y = v[p] -= MX;
            }
            z = v[n - 1];
            y = v[0] -= MX;
            sum -= DELTA;
        }while(--rounds);
    }

    return;
}