// Rabin-Miller method for finding a strong pseudo-prime
// Preconditions: High bit and low bit of n = 1
bool RabinMillerPrimeTest(
IRandom *prng,
const u32 *n, // Number to check for primality
int limbs, // Number of limbs in n
u32 k) // Confidence level (40 is pretty good)
{
// n1 = n - 1
u32 *n1 = (u32 *)alloca(limbs*4);
Set(n1, limbs, n);
Subtract32(n1, limbs, 1);
// d = n1
u32 *d = (u32 *)alloca(limbs*4);
Set(d, limbs, n1);
// remove factors of two from d
while (!(d[0] & 1))
ShiftRight(limbs, d, d, 1);
u32 *a = (u32 *)alloca(limbs*4);
u32 *t = (u32 *)alloca(limbs*4);
u32 *p = (u32 *)alloca((limbs*2)*4);
u32 n_inv = MonReducePrecomp(n[0]);
// iterate k times
while (k--)
{
do prng->Generate(a, limbs*4);
while (GreaterOrEqual(a, limbs, n, limbs));
// a = a ^ d (Mod n)
ExpMod(a, limbs, d, limbs, n, limbs, n_inv, a);
Set(t, limbs, d);
while (!Equal(limbs, t, n1) &&
!Equal32(a, limbs, 1) &&
!Equal(limbs, a, n1))
{
// TODO: verify this is actually working
// a = a^2 (Mod n), non-critical path
Square(limbs, p, a);
Modulus(p, limbs*2, n, limbs, a);
// t <<= 1
ShiftLeft(limbs, t, t, 1);
}
if (!Equal(limbs, a, n1) && !(t[0] & 1)) return false;
}
return true;
}
void Greater() {
Match('>');
if(Look == '=') {
GreaterOrEqual();
}
else {
Expression();
Compare();
SetGreater();
Pop();
}
}
template <bool align> v128_u8 LbpEstimate(const uint8_t * src, ptrdiff_t stride)
{
v128_u8 threshold = Load<false>(src);
v128_u8 lbp = K8_00;
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<align>(src - 1 - stride), threshold), K8_01));
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<false>(src - stride), threshold), K8_02));
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<false>(src + 1 - stride), threshold), K8_04));
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<false>(src + 1 ), threshold), K8_08));
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<false>(src + 1 + stride), threshold), K8_10));
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<false>(src + stride), threshold), K8_20));
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<align>(src - 1 + stride), threshold), K8_40));
lbp = vec_or(lbp, vec_and(GreaterOrEqual(Load<align>(src - 1 ), threshold), K8_80));
return lbp;
}
