Commit adeaf7db authored by Nguyen, Thien Minh's avatar Nguyen, Thien Minh
Browse files

Added modular multiply in place 


i.e. swap the result from aux qreg to the operand qreg

Signed-off-by: default avatarThien Nguyen <nguyentm@ornl.gov>
parent ea9a1c91

lib/impl/integer_arithmetic.hpp

+50 −0
Original line number Diff line number Diff line
@@ -26,6 +26,38 @@ void genAngles(std::vector<double> &io_angles, int a, int nbQubits) { 
inline void calcPowMultMod(int &result, int i, int a, int N) {

  result = (1 << i) * a % N;

}



// Compute extended greatest common divisor of two integers

inline std::tuple<int, int, int> egcd(int a, int b) {

  int m, n, c, q, r;

  int m1 = 0, m2 = 1, n1 = 1, n2 = 0;



  while (b) {

    q = a / b, r = a - q * b;

    m = m2 - q * m1, n = n2 - q * n1;

    a = b, b = r;

    m2 = m1, m1 = m, n2 = n1, n1 = n;

  }



  c = a, m = m2, n = n2;



  // correct the signs

  if (c < 0) {

    m = -m;

    n = -n;

    c = -c;

  }



  return std::make_tuple(m, n, c);

}



// Modular inverse of a mod p

inline void modinv(int &result, int a, int p) {

  int x, y;

  int gcd_ap;

  std::tie(x, y, gcd_ap) = egcd(p, a);

  result = (y > 0) ? y : y + p;

}

} // namespace internal

} // namespace qcor
@@ -138,3 +170,21 @@ __qpu__ void mul_integer_mod(qreg x, qreg b, qubit anc, int a, int N) { 
  compute { qft_opt_swap(b, 0); }

  action { phase_mul_integer_mod(x, b, anc, a, N); }

}



// Modular multiply in-place:

// See Fig. 7 (https://arxiv.org/pdf/quant-ph/0205095.pdf)

// |x>|0> ==> |ax mod N>|0>

// x and aux_reg must have the same size.

__qpu__ void mul_integer_mod_in_place(qreg x, qreg aux_reg, qubit anc, int a, int N) {

  Reset(aux_reg);

  mul_integer_mod(x, aux_reg, anc, a, N);

  // Swap the result to x register

  for (int i = 0; i < x.size(); ++i) {

    Swap(x[i], aux_reg[i]);

  }



  int aInv = 0;

  qcor::internal::modinv(aInv, a, N);

  // Apply modular multiply of 1/a

  mul_integer_mod::adjoint(x, aux_reg, anc, aInv, N);

}
 
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