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extern/draco/dracoenc/src/draco/core/divide.h
- This file was added.
| // Copyright 2016 The Draco Authors. | |||||
| // | |||||
| // 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 | |||||
| // | |||||
| // http://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. | |||||
| // | |||||
| #ifndef DRACO_CORE_DIVIDE_H_ | |||||
| #define DRACO_CORE_DIVIDE_H_ | |||||
| // An implementation of the divide by multiply algorithm | |||||
| // https://gmplib.org/~tege/divcnst-pldi94.pdf | |||||
| // This file is based off libvpx's divide.h. | |||||
| #include <stdint.h> | |||||
| #include <climits> | |||||
| namespace draco { | |||||
| struct fastdiv_elem { | |||||
| unsigned mult; | |||||
| unsigned shift; | |||||
| }; | |||||
| extern const struct fastdiv_elem vp10_fastdiv_tab[256]; | |||||
| static inline unsigned fastdiv(unsigned x, int y) { | |||||
| unsigned t = | |||||
| ((uint64_t)x * vp10_fastdiv_tab[y].mult) >> (sizeof(x) * CHAR_BIT); | |||||
| return (t + x) >> vp10_fastdiv_tab[y].shift; | |||||
| } | |||||
| } // namespace draco | |||||
| #endif // DRACO_CORE_DIVIDE_H_ | |||||