1 files changed, 50 insertions, 0 deletions
diff --git a/src/crc32c_sse42_check.h b/src/crc32c_sse42_check.h
new file mode 100644
index 0000000000..e7528912a6
--- /dev/null
+++ b/src/crc32c_sse42_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.
+
+#ifndef CRC32C_CRC32C_SSE42_CHECK_H_
+#define CRC32C_CRC32C_SSE42_CHECK_H_
+
+// X86-specific code checking the availability of SSE4.2 instructions.
+
+#include <cstddef>
+#include <cstdint>
+
+#ifdef CRC32C_HAVE_CONFIG_H
+#include "crc32c/crc32c_config.h"
+#endif
+
+#if HAVE_SSE42 && (defined(_M_X64) || defined(__x86_64__))
+
+// If the compiler supports SSE4.2, it definitely supports X86.
+
+#if defined(_MSC_VER)
+#include <intrin.h>
+
+namespace crc32c {
+
+inline bool CanUseSse42() {
+  int cpu_info[4];
+  __cpuid(cpu_info, 1);
+  return (cpu_info[2] & (1 << 20)) != 0;
+}
+
+}  // namespace crc32c
+
+#else  // !defined(_MSC_VER)
+#include <cpuid.h>
+
+namespace crc32c {
+
+inline bool CanUseSse42() {
+  unsigned int eax, ebx, ecx, edx;
+  return __get_cpuid(1, &eax, &ebx, &ecx, &edx) && ((ecx & (1 << 20)) != 0);
+}
+
+}  // namespace crc32c
+
+#endif  // defined(_MSC_VER)
+
+#endif  // HAVE_SSE42 && (defined(_M_X64) || defined(__x86_64__))
+
+#endif  // CRC32C_CRC32C_SSE42_CHECK_H_