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- /*
- * Copyright 2017 Google LLC.
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- #include "ntt_parameters.h"
- namespace rlwe {
- namespace internal {
- // Bit reverse only among the rightmost log_n bytes.
- unsigned int Bitrev(unsigned int input, unsigned int log_n) {
- unsigned int output = 0;
- for (unsigned int i = 0; i < log_n; i++) {
- output <<= 1;
- output |= input & 0x01;
- input >>= 1;
- }
- return output;
- }
- std::vector<unsigned int> BitrevArray(unsigned int log_n) {
- unsigned int n = 1 << log_n;
- std::vector<unsigned int> output(n);
- for (unsigned int i = 0; i < n; i++) {
- output[i] = Bitrev(i, log_n);
- }
- return output;
- }
- } // namespace internal
- } // namespace rlwe
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