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Diffstat (limited to 'src/crc32c_arm64_linux_check.h')
-rw-r--r-- | src/crc32c_arm64_linux_check.h | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/src/crc32c_arm64_linux_check.h b/src/crc32c_arm64_linux_check.h new file mode 100644 index 0000000000..1a20a757bb --- /dev/null +++ b/src/crc32c_arm64_linux_check.h @@ -0,0 +1,50 @@ +// 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_ |