1 files changed, 119 insertions, 0 deletions
diff --git a/abseil-cpp/absl/crc/internal/crc_memcpy.h b/abseil-cpp/absl/crc/internal/crc_memcpy.h
new file mode 100644
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--- /dev/null
+++ b/abseil-cpp/absl/crc/internal/crc_memcpy.h
@@ -0,0 +1,119 @@
+// 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_CRC_MEMCPY_H_
+#define ABSL_CRC_INTERNAL_CRC_MEMCPY_H_
+
+#include <cstddef>
+#include <memory>
+
+#include "absl/base/config.h"
+#include "absl/crc/crc32c.h"
+
+// Defined if the class AcceleratedCrcMemcpyEngine exists.
+#if defined(__x86_64__) && defined(__SSE4_2__)
+#define ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE 1
+#elif defined(_MSC_VER) && defined(__AVX__)
+#define ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE 1
+#endif
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace crc_internal {
+
+class CrcMemcpyEngine {
+ public:
+  virtual ~CrcMemcpyEngine() = default;
+
+  virtual crc32c_t Compute(void* __restrict dst, const void* __restrict src,
+                           std::size_t length, crc32c_t initial_crc) const = 0;
+
+ protected:
+  CrcMemcpyEngine() = default;
+};
+
+class CrcMemcpy {
+ public:
+  static crc32c_t CrcAndCopy(void* __restrict dst, const void* __restrict src,
+                             std::size_t length,
+                             crc32c_t initial_crc = crc32c_t{0},
+                             bool non_temporal = false) {
+    static const ArchSpecificEngines engines = GetArchSpecificEngines();
+    auto* engine = non_temporal ? engines.non_temporal : engines.temporal;
+    return engine->Compute(dst, src, length, initial_crc);
+  }
+
+  // For testing only: get an architecture-specific engine for tests.
+  static std::unique_ptr<CrcMemcpyEngine> GetTestEngine(int vector,
+                                                        int integer);
+
+ private:
+  struct ArchSpecificEngines {
+    CrcMemcpyEngine* temporal;
+    CrcMemcpyEngine* non_temporal;
+  };
+
+  static ArchSpecificEngines GetArchSpecificEngines();
+};
+
+// Fallback CRC-memcpy engine.
+class FallbackCrcMemcpyEngine : public CrcMemcpyEngine {
+ public:
+  FallbackCrcMemcpyEngine() = default;
+  FallbackCrcMemcpyEngine(const FallbackCrcMemcpyEngine&) = delete;
+  FallbackCrcMemcpyEngine operator=(const FallbackCrcMemcpyEngine&) = delete;
+
+  crc32c_t Compute(void* __restrict dst, const void* __restrict src,
+                   std::size_t length, crc32c_t initial_crc) const override;
+};
+
+// CRC Non-Temporal-Memcpy engine.
+class CrcNonTemporalMemcpyEngine : public CrcMemcpyEngine {
+ public:
+  CrcNonTemporalMemcpyEngine() = default;
+  CrcNonTemporalMemcpyEngine(const CrcNonTemporalMemcpyEngine&) = delete;
+  CrcNonTemporalMemcpyEngine operator=(const CrcNonTemporalMemcpyEngine&) =
+      delete;
+
+  crc32c_t Compute(void* __restrict dst, const void* __restrict src,
+                   std::size_t length, crc32c_t initial_crc) const override;
+};
+
+// CRC Non-Temporal-Memcpy AVX engine.
+class CrcNonTemporalMemcpyAVXEngine : public CrcMemcpyEngine {
+ public:
+  CrcNonTemporalMemcpyAVXEngine() = default;
+  CrcNonTemporalMemcpyAVXEngine(const CrcNonTemporalMemcpyAVXEngine&) = delete;
+  CrcNonTemporalMemcpyAVXEngine operator=(
+      const CrcNonTemporalMemcpyAVXEngine&) = delete;
+
+  crc32c_t Compute(void* __restrict dst, const void* __restrict src,
+                   std::size_t length, crc32c_t initial_crc) const override;
+};
+
+// Copy source to destination and return the CRC32C of the data copied.  If an
+// accelerated version is available, use the accelerated version, otherwise use
+// the generic fallback version.
+inline crc32c_t Crc32CAndCopy(void* __restrict dst, const void* __restrict src,
+                              std::size_t length,
+                              crc32c_t initial_crc = crc32c_t{0},
+                              bool non_temporal = false) {
+  return CrcMemcpy::CrcAndCopy(dst, src, length, initial_crc, non_temporal);
+}
+
+}  // namespace crc_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CRC_INTERNAL_CRC_MEMCPY_H_