// out is the counter on entry, the output when done.
void philox(unsigned int out[4], const unsigned int key[2])
{
const unsigned int mult[2] = {0xCD9E8D57, 0xD2511F53};
int rnd, i;
// Iterate and do each round in turn, updating the counter before we finally return it (Indexing from 1 is conveniant for the Weyl sequence.)...
for (rnd=1;rnd<=10;rnd++)
{
// Calculate key for this step, by applying the Weyl sequence on it...
unsigned int keyWeyl[2];
keyWeyl[0] = key[0] * rnd;
keyWeyl[1] = key[1] * rnd;
// Apply the s-blocks, also swap the r values between the s-blocks...
unsigned int next[4];
next[0] = out[1] * mult[0];
next[2] = out[3] * mult[1];
next[3] = mul_hi(out[1],mult[0]) ^ keyWeyl[0] ^ out[0];
next[1] = mul_hi(out[3],mult[1]) ^ keyWeyl[1] ^ out[2];
// Prepare for the next step...
for (i=0;i<4;i++) out[i] = next[i];
}
}
INTERVAL mulDDI(double a, double b) {
INTERVAL c;
if ((a==0) || (b == 0)) {
c.lo = c.hi = 0; return(c);}
c.lo = mul_lo(a,b);
c.hi = mul_hi(a,b);
return(c);
}
