bitfield.cpp

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// Copyright (c) 2019 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <script/bitfield.h>
 
#include <script/script_error.h>
 
#include <cstddef>
#include <limits>
 
bool DecodeBitfield(const std::vector<uint8_t> &vch, unsigned size,
                    uint32_t &bitfield, ScriptError *serror) {
    if (size > 32) {
        return set_error(serror, ScriptError::INVALID_BITFIELD_SIZE);
    }
 
    const size_t bitfield_size = (size + 7) / 8;
    if (vch.size() != bitfield_size) {
        return set_error(serror, ScriptError::INVALID_BITFIELD_SIZE);
    }
 
    bitfield = 0;
    for (size_t i = 0; i < bitfield_size; i++) {
        // Decode the bitfield as little endian.
        bitfield |= uint32_t(vch[i]) << (8 * i);
    }
 
    const uint32_t mask = (uint64_t(1) << size) - 1;
    if ((bitfield & mask) != bitfield) {
        return set_error(serror, ScriptError::INVALID_BIT_RANGE);
    }
 
    return true;
}