#include "xxtea.h"
#define MX ((z>>5)^(y<<2)) + (((y>>3)^(z<<4))^(sum^y)) + (k[(p&3)^e]^z);

long btea(long* v, long n, long* k)
{
	unsigned long z=v[n-1], y=v[0], sum=0, e, DELTA=0x9e3779b9;
	long p, q ;
	if (n > 1)/* Coding Part */
	{
		q = 6 + 52/n;
		while (q-- > 0)
		{
			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;
		}
		return 0 ; 
	}
	else if (n < -1)/* Decoding Part */
	{
		n = -n;
		q = 6 + 52/n;
		sum = q*DELTA ;
		while (sum != 0)
		{
			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;
		}
		return 0;
	}
	return 1;
}

void encipher(unsigned int num_rounds, uint32_t v[2], uint32_t const key[4]) {
    unsigned int i;
    uint32_t v0=v[0], v1=v[1], sum=0, delta=0x9E3779B9;
    for (i=0; i < num_rounds; i++) {
        v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
        sum += delta;
        v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum>>11) & 3]);
    }
    v[0]=v0; v[1]=v1;
}
 
void decipher(unsigned int num_rounds, uint32_t v[2], uint32_t const key[4]) {
    unsigned int i;
    uint32_t v0=v[0], v1=v[1], delta=0x9E3779B9, sum=delta*num_rounds;
    for (i=0; i < num_rounds; i++) {
        v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum>>11) & 3]);
        sum -= delta;
        v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
    }
    v[0]=v0; v[1]=v1;
}

void tea_encrypt(unsigned long* v, unsigned long* k) 
{
     unsigned long v0=v[0], v1=v[1], sum=0, i;           
     unsigned long delta=0x7937b913;                    
     unsigned long k0=k[0], k1=k[1], k2=k[2], k3=k[3];   
     for (i=0; i < 15; i++)
    {                            
         sum += delta;
         v0 += ((v1<<4) + k0) ^ (v1 + sum) ^ ((v1>>5) + k1);
         v1 += ((v0<<4) + k2) ^ (v0 + sum) ^ ((v0>>5) + k3); 
     }
     v[0]=v0; v[1]=v1;
 }
 
 void tea_decrypt(unsigned long* v, unsigned long* k) 
{     
     unsigned long v0=v[0], v1=v[1], sum=0x1a43d81d, i; 
     unsigned long delta=0x7937b913;                          
     unsigned long k0=k[0], k1=k[1], k2=k[2], k3=k[3];     
     for(i=0; i<15; i++) 
     {                               
         v1 -= ((v0<<4) + k2) ^ (v0 + sum) ^ ((v0>>5) + k3);
         v0 -= ((v1<<4) + k0) ^ (v1 + sum) ^ ((v1>>5) + k1);
         sum -= delta;                 
     }
     v[0]=v0; v[1]=v1;
 }