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71 lines
2.0 KiB
71 lines
2.0 KiB
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ___FEC_ECC_H___
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#define ___FEC_ECC_H___
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#include <fec/io.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* ecc parameters */
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#define FEC_RSM 255
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/* parameters to init_rs_char */
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#define FEC_PARAMS(roots) \
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8, /* symbol size in bits */ \
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0x11d, /* field generator polynomial coefficients */ \
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0, /* first root of the generator */ \
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1, /* primitive element to generate polynomial roots */ \
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(roots), /* polynomial degree (number of roots) */ \
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0 /* padding bytes at the front of shortened block */
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/* computes ceil(x / y) */
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inline uint64_t fec_div_round_up(uint64_t x, uint64_t y)
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{
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return (x / y) + (x % y > 0 ? 1 : 0);
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}
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/* rounds up x to the nearest multiple of y */
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inline uint64_t fec_round_up(uint64_t x, uint64_t y)
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{
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return fec_div_round_up(x, y) * y;
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}
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/* returns a physical offset for a byte in an RS block */
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inline uint64_t fec_ecc_interleave(uint64_t offset, int rsn, uint64_t rounds)
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{
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return (offset / rsn) + (offset % rsn) * rounds * FEC_BLOCKSIZE;
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}
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/* returns the size of ecc data given a file size and the number of roots */
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inline uint64_t fec_ecc_get_size(uint64_t file_size, int roots)
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{
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return fec_div_round_up(fec_div_round_up(file_size, FEC_BLOCKSIZE),
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FEC_RSM - roots)
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* roots * FEC_BLOCKSIZE
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+ FEC_BLOCKSIZE;
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}
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif /* ___FEC_ECC_H___ */
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