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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab ft=cpp
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2023 Red Hat, Inc
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#pragma once
#include <bit>
#include <array>
#include <concepts>
#include <algorithm>
#include <stdio.h>
#include "include/crc32c.h"
#include <boost/crc.hpp>
namespace rgw { namespace digest {
/* crib impl of c++23 std::byteswap from
* https://en.cppreference.com/w/cpp/numeric/byteswap */
template <std::integral T> constexpr T byteswap(T value) noexcept {
static_assert(std::has_unique_object_representations_v<T>,
"T may not have padding bits");
auto value_representation =
std::bit_cast<std::array<std::byte, sizeof(T)>>(value);
std::ranges::reverse(value_representation);
return std::bit_cast<T>(value_representation);
} /* byteswap */
/* impl. using boost::crc, as configured by imtzw */
class Crc32 {
private:
using crc32_type = boost::crc_optimal<
32, 0x04C11DB7, 0xFFFFFFFF, 0xFFFFFFFF, true, true>;
crc32_type crc;
public:
static constexpr uint16_t digest_size = 4;
Crc32() { Restart(); }
void Restart() { crc.reset(); }
void Update(const unsigned char *data, uint64_t len) {
crc.process_bytes(data, len);
}
void Final(unsigned char* digest) {
/* XXX crc32 and cksfb utilities both treat the byteswapped result
* as canonical--possibly this needs to be omitted when BigEndian? */
uint32_t final = crc();
if constexpr (std::endian::native != std::endian::big) {
final = rgw::digest::byteswap(final);
}
memcpy((char*) digest, &final, sizeof(final));
}
}; /* Crc32 */
/* use Ceph hw-specialized crc32c (0x1EDC6F41) */
class Crc32c {
private:
uint32_t crc;
public:
static constexpr uint16_t digest_size = 4;
static constexpr uint32_t initial_value = 0xffffffff;
Crc32c() { Restart(); }
void Restart() { crc = initial_value; }
void Update(const unsigned char *data, uint64_t len) {
crc = ceph_crc32c(crc, data, len);
}
void Final(unsigned char* digest) {
crc = crc ^ 0xffffffff;
if constexpr (std::endian::native != std::endian::big) {
crc = rgw::digest::byteswap(crc);
}
memcpy((char*) digest, &crc, sizeof(crc));
}
}; /* Crc32c */
}} /* namespace */
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