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/*
* Copyright (c) 2020-2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Array.h>
#include <AK/Span.h>
#include <AK/Types.h>
#include <LibCrypto/Checksum/CRC32.h>
namespace Crypto::Checksum {
#if defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
void CRC32::update(ReadonlyBytes span)
{
// FIXME: Does this require runtime checking on rpi?
// (Maybe the instruction is present on the rpi4 but not on the rpi3?)
u8 const* data = span.data();
size_t size = span.size();
while (size > 0 && (reinterpret_cast<FlatPtr>(data) & 7) != 0) {
m_state = __builtin_arm_crc32b(m_state, *data);
++data;
--size;
}
auto* data64 = reinterpret_cast<u64 const*>(data);
while (size >= 8) {
m_state = __builtin_arm_crc32d(m_state, *data64);
++data64;
size -= 8;
}
data = reinterpret_cast<u8 const*>(data64);
while (size > 0) {
m_state = __builtin_arm_crc32b(m_state, *data);
++data;
--size;
}
};
// FIXME: On Intel, use _mm_crc32_u8 / _mm_crc32_u64 if available (SSE 4.2).
#else
static constexpr auto generate_table()
{
Array<u32, 256> data {};
for (auto i = 0u; i < data.size(); i++) {
u32 value = i;
for (auto j = 0; j < 8; j++) {
if (value & 1) {
value = 0xEDB88320 ^ (value >> 1);
} else {
value = value >> 1;
}
}
data[i] = value;
}
return data;
}
static constexpr auto table = generate_table();
void CRC32::update(ReadonlyBytes data)
{
for (size_t i = 0; i < data.size(); i++) {
m_state = table[(m_state ^ data.at(i)) & 0xFF] ^ (m_state >> 8);
}
};
#endif
u32 CRC32::digest()
{
return ~m_state;
}
}
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