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/*
* Copyright (C) 2015 The Android Open Source Project
*
* 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 ___FEC_ECC_H___
#define ___FEC_ECC_H___
#include <fec/io.h>
#ifdef __cplusplus
extern "C" {
#endif
/* ecc parameters */
#define FEC_RSM 255
/* parameters to init_rs_char */
#define FEC_PARAMS(roots) \
8, /* symbol size in bits */ \
0x11d, /* field generator polynomial coefficients */ \
0, /* first root of the generator */ \
1, /* primitive element to generate polynomial roots */ \
(roots), /* polynomial degree (number of roots) */ \
0 /* padding bytes at the front of shortened block */
/* computes ceil(x / y) */
inline uint64_t fec_div_round_up(uint64_t x, uint64_t y)
{
return (x / y) + (x % y > 0 ? 1 : 0);
}
/* rounds up x to the nearest multiple of y */
inline uint64_t fec_round_up(uint64_t x, uint64_t y)
{
return fec_div_round_up(x, y) * y;
}
/* returns a physical offset for a byte in an RS block */
inline uint64_t fec_ecc_interleave(uint64_t offset, int rsn, uint64_t rounds)
{
return (offset / rsn) + (offset % rsn) * rounds * FEC_BLOCKSIZE;
}
/* returns the size of ecc data given a file size and the number of roots */
inline uint64_t fec_ecc_get_size(uint64_t file_size, int roots)
{
return fec_div_round_up(fec_div_round_up(file_size, FEC_BLOCKSIZE),
FEC_RSM - roots)
* roots * FEC_BLOCKSIZE
+ FEC_BLOCKSIZE;
}
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* ___FEC_ECC_H___ */
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