// Copyright (c) 2018-2022 The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_UTIL_GOLOMBRICE_H

#define BITCOIN_UTIL_GOLOMBRICE_H

#include <util/fastrange.h>

#include <streams.h>

#include <cstdint>

template <typename OStream>

void GolombRiceEncode(BitStreamWriter<OStream>& bitwriter, uint8_t P, uint64_t x)

{

    // Write quotient as unary-encoded: q 1's followed by one 0.

    uint64_t q = x >> P;

    while (q > 0) {

        int nbits = q <= 64 ? static_cast<int>(q) : 64;

        bitwriter.Write(~0ULL, nbits);

        q -= nbits;

    }

    bitwriter.Write(0, 1);

    // Write the remainder in P bits. Since the remainder is just the bottom

    // P bits of x, there is no need to mask first.

    bitwriter.Write(x, P);

}

template <typename IStream>

uint64_t GolombRiceDecode(BitStreamReader<IStream>& bitreader, uint8_t P)

{

    // Read unary-encoded quotient: q 1's followed by one 0.

    uint64_t q = 0;

    while (bitreader.Read(1) == 1) {

        ++q;

    }

    uint64_t r = bitreader.Read(P);

    return (q << P) + r;

}

#endif // BITCOIN_UTIL_GOLOMBRICE_H