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// Copyright 2022 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_CRC_INTERNAL_CRC32C_INLINE_H_
#define ABSL_CRC_INTERNAL_CRC32C_INLINE_H_
#include <cstdint>
#include "absl/base/config.h"
#include "absl/base/internal/endian.h"
#include "absl/crc/internal/crc32_x86_arm_combined_simd.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace crc_internal {
// CRC32C implementation optimized for small inputs.
// Either computes crc and return true, or if there is
// no hardware support does nothing and returns false.
inline bool ExtendCrc32cInline(uint32_t* crc, const char* p, size_t n) {
#if defined(ABSL_CRC_INTERNAL_HAVE_ARM_SIMD) || \
defined(ABSL_CRC_INTERNAL_HAVE_X86_SIMD)
constexpr uint32_t kCrc32Xor = 0xffffffffU;
*crc ^= kCrc32Xor;
if (n & 1) {
*crc = CRC32_u8(*crc, *p);
n--;
p++;
}
if (n & 2) {
*crc = CRC32_u16(*crc, absl::little_endian::Load16(p));
n -= 2;
p += 2;
}
if (n & 4) {
*crc = CRC32_u32(*crc, absl::little_endian::Load32(p));
n -= 4;
p += 4;
}
while (n) {
*crc = CRC32_u64(*crc, absl::little_endian::Load64(p));
n -= 8;
p += 8;
}
*crc ^= kCrc32Xor;
return true;
#else
// No hardware support, signal the need to fallback.
static_cast<void>(crc);
static_cast<void>(p);
static_cast<void>(n);
return false;
#endif // defined(ABSL_CRC_INTERNAL_HAVE_ARM_SIMD) ||
// defined(ABSL_CRC_INTERNAL_HAVE_X86_SIMD)
}
} // namespace crc_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_CRC_INTERNAL_CRC32C_INLINE_H_
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