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44 lines
1.2 KiB
C
44 lines
1.2 KiB
C
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// Copyright (c) 2018-2019 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_UTIL_GOLOMBRICE_H
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#define BITCOIN_UTIL_GOLOMBRICE_H
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#include <streams.h>
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#include <cstdint>
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template <typename OStream>
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void GolombRiceEncode(BitStreamWriter<OStream>& bitwriter, uint8_t P, uint64_t x)
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{
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// Write quotient as unary-encoded: q 1's followed by one 0.
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uint64_t q = x >> P;
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while (q > 0) {
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int nbits = q <= 64 ? static_cast<int>(q) : 64;
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bitwriter.Write(~0ULL, nbits);
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q -= nbits;
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}
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bitwriter.Write(0, 1);
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// Write the remainder in P bits. Since the remainder is just the bottom
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// P bits of x, there is no need to mask first.
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bitwriter.Write(x, P);
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}
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template <typename IStream>
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uint64_t GolombRiceDecode(BitStreamReader<IStream>& bitreader, uint8_t P)
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{
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// Read unary-encoded quotient: q 1's followed by one 0.
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uint64_t q = 0;
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while (bitreader.Read(1) == 1) {
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++q;
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}
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uint64_t r = bitreader.Read(P);
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return (q << P) + r;
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}
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#endif // BITCOIN_UTIL_GOLOMBRICE_H
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