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// Copyright 2017 The CRC32C Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
// ARM Linux-specific code checking for the availability of CRC32C instructions.
#ifndef CRC32C_CRC32C_ARM_LINUX_CHECK_H_
#define CRC32C_CRC32C_ARM_LINUX_CHECK_H_
// X86-specific code checking for the availability of SSE4.2 instructions.
#include <cstddef>
#include <cstdint>
#ifdef CRC32C_HAVE_CONFIG_H
#include "crc32c/crc32c_config.h"
#endif
#if HAVE_ARM64_CRC32C
#if HAVE_STRONG_GETAUXVAL
#include <sys/auxv.h>
#elif HAVE_WEAK_GETAUXVAL
// getauxval() is not available on Android until API level 20. Link it as a weak
// symbol.
extern "C" unsigned long getauxval(unsigned long type) __attribute__((weak));
#define AT_HWCAP 16
#endif // HAVE_STRONG_GETAUXVAL || HAVE_WEAK_GETAUXVAL
namespace crc32c {
inline bool CanUseArm64Linux() {
#if HAVE_STRONG_GETAUXVAL || HAVE_WEAK_GETAUXVAL
// From 'arch/arm64/include/uapi/asm/hwcap.h' in Linux kernel source code.
constexpr unsigned long kHWCAP_PMULL = 1 << 4;
constexpr unsigned long kHWCAP_CRC32 = 1 << 7;
unsigned long hwcap = (&getauxval != nullptr) ? getauxval(AT_HWCAP) : 0;
return (hwcap & (kHWCAP_PMULL | kHWCAP_CRC32)) ==
(kHWCAP_PMULL | kHWCAP_CRC32);
#else
return false;
#endif // HAVE_STRONG_GETAUXVAL || HAVE_WEAK_GETAUXVAL
}
} // namespace crc32c
#endif // HAVE_ARM64_CRC32C
#endif // CRC32C_CRC32C_ARM_LINUX_CHECK_H_
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