Longfellow ZK 0290cb32

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permutations.h
1// Copyright 2025 Google LLC.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#ifndef PRIVACY_PROOFS_ZK_LIB_ALGEBRA_PERMUTATIONS_H_
16#define PRIVACY_PROOFS_ZK_LIB_ALGEBRA_PERMUTATIONS_H_
17
18#include <stddef.h>
19
20#include <utility>
21
22 namespace proofs {
23
24 template <class Elt>
25 class Permutations {
26 public:
27 static void bitrev(Elt A[/*n*/], size_t n) {
28 size_t revi = 0;
29 for (size_t i = 0; i < n - 1; ++i) {
30 if (i < revi) {
31 std::swap(A[i], A[revi]);
32 }
33
34 bitrev_increment(&revi, n);
35 }
36 }
37
38 private:
39 static void bitrev_increment(size_t* j, size_t bit) {
40 do {
41 bit >>= 1;
42 *j ^= bit;
43 } while (!(*j & bit));
44 }
45};
46} // namespace proofs
47
48#endif // PRIVACY_PROOFS_ZK_LIB_ALGEBRA_PERMUTATIONS_H_
proofs::Permutations
Definition permutations.h:25