1 #include <cln/integer.h>
2 #include <cln/modinteger.h>
5 #include "cra_garner.hpp"
14 retract_symm(const cl_MI& x, const cl_modint_ring& R,
17 cl_I result = R->retract(x);
18 if (result > (modulus >> 1))
19 result = result - modulus;
24 compute_recips(vector<cl_MI>& dst,
25 const vector<cl_I>& moduli)
27 for (size_t k = 1; k < moduli.size(); ++k) {
28 cl_modint_ring R = find_modint_ring(moduli[k]);
29 cl_MI product = R->canonhom(moduli[0]);
30 for (size_t i = 1; i < k; ++i)
31 product = product*moduli[i];
32 dst[k-1] = recip(product);
37 compute_mix_radix_coeffs(vector<cl_I>& dst,
38 const vector<cl_I>& residues,
39 const vector<cl_I>& moduli,
40 const vector<cl_MI>& recips)
45 cl_modint_ring R = find_modint_ring(moduli[1]);
46 cl_MI tmp = R->canonhom(residues[0]);
47 cl_MI next = (R->canonhom(residues[1]) - tmp)*recips[0];
48 dst[1] = retract_symm(next, R, moduli[1]);
51 for (size_t k = 2; k < residues.size(); ++k) {
52 cl_modint_ring R = find_modint_ring(moduli[k]);
53 cl_MI tmp = R->canonhom(dst[k-1]);
55 for (size_t j = k - 1 /* NOT k - 2 */; j-- != 0; )
56 tmp = tmp*moduli[j] + R->canonhom(dst[j]);
58 cl_MI next = (R->canonhom(residues[k]) - tmp)*recips[k-1];
59 dst[k] = retract_symm(next, R, moduli[k]);
64 mixed_radix_2_ordinary(const vector<cl_I>& mixed_radix_coeffs,
65 const vector<cl_I>& moduli)
67 size_t k = mixed_radix_coeffs.size() - 1;
68 cl_I u = mixed_radix_coeffs[k];
70 u = u*moduli[k] + mixed_radix_coeffs[k];
74 cl_I integer_cra(const vector<cl_I>& residues,
75 const vector<cl_I>& moduli)
77 if (unlikely(moduli.size() < 2))
78 throw std::invalid_argument("integer_cra: need at least 2 moduli");
80 vector<cl_MI> recips(moduli.size() - 1);
81 compute_recips(recips, moduli);
83 vector<cl_I> coeffs(moduli.size());
84 compute_mix_radix_coeffs(coeffs, residues, moduli, recips);
85 cl_I result = mixed_radix_2_ordinary(coeffs, moduli);