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diff --git a/absl/crc/crc32c.h b/absl/crc/crc32c.h
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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.
+//
+// -----------------------------------------------------------------------------
+// File: crc32c.h
+// -----------------------------------------------------------------------------
+//
+// This header file defines the API for computing CRC32C values as checksums
+// for arbitrary sequences of bytes provided as a string buffer.
+//
+// The API includes the basic functions for computing such CRC32C values and
+// some utility functions for performing more efficient mathematical
+// computations using an existing checksum.
+#ifndef ABSL_CRC_CRC32C_H_
+#define ABSL_CRC_CRC32C_H_
+
+#include <cstdint>
+#include <iostream>
+#include <ostream>
+
+#include "absl/crc/internal/crc32c_inline.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+//-----------------------------------------------------------------------------
+// crc32c_t
+//-----------------------------------------------------------------------------
+
+// `crc32c_t` defines a strongly typed integer type for holding a CRC32C value.
+enum class crc32c_t : uint32_t {};
+
+// ToCrc32c()
+//
+// Converts a uint32_t value to crc32c_t. This API is necessary in C++14
+// and earlier. Code targeting C++17-or-later can instead use `crc32c_t{n}`.
+inline crc32c_t ToCrc32c(uint32_t n) {
+  return static_cast<crc32c_t>(n);
+}
+// operator^
+//
+// Performs a bitwise XOR on two CRC32C values
+inline crc32c_t operator^(crc32c_t lhs, crc32c_t rhs) {
+  const auto lhs_int = static_cast<uint32_t>(lhs);
+  const auto rhs_int = static_cast<uint32_t>(rhs);
+  return ToCrc32c(lhs_int ^ rhs_int);
+}
+
+namespace crc_internal {
+// Non-inline code path for `absl::ExtendCrc32c()`. Do not call directly.
+// Call `absl::ExtendCrc32c()` (defined below) instead.
+crc32c_t ExtendCrc32cInternal(crc32c_t initial_crc,
+                              absl::string_view buf_to_add);
+}  // namespace crc_internal
+
+// -----------------------------------------------------------------------------
+// CRC32C Computation Functions
+// -----------------------------------------------------------------------------
+
+// ComputeCrc32c()
+//
+// Returns the CRC32C value of the provided string.
+crc32c_t ComputeCrc32c(absl::string_view buf);
+
+// ExtendCrc32c()
+//
+// Computes a CRC32C value from an `initial_crc` CRC32C value including the
+// `buf_to_add` bytes of an additional buffer. Using this function is more
+// efficient than computing a CRC32C value for the combined buffer from
+// scratch.
+//
+// Note: `ExtendCrc32c` with an initial_crc of 0 is equivalent to
+// `ComputeCrc32c`.
+//
+// This operation has a runtime cost of O(`buf_to_add.size()`)
+inline crc32c_t ExtendCrc32c(crc32c_t initial_crc,
+                             absl::string_view buf_to_add) {
+  // Approximately 75% of calls have size <= 64.
+  if (buf_to_add.size() <= 64) {
+    uint32_t crc = static_cast<uint32_t>(initial_crc);
+    if (crc_internal::ExtendCrc32cInline(&crc, buf_to_add.data(),
+                                         buf_to_add.size())) {
+      return ToCrc32c(crc);
+    }
+  }
+  return crc_internal::ExtendCrc32cInternal(initial_crc, buf_to_add);
+}
+
+// ExtendCrc32cByZeroes()
+//
+// Computes a CRC32C value for a buffer with an `initial_crc` CRC32C value,
+// where `length` bytes with a value of 0 are appended to the buffer. Using this
+// function is more efficient than computing a CRC32C value for the combined
+// buffer from scratch.
+//
+// This operation has a runtime cost of O(log(`length`))
+crc32c_t ExtendCrc32cByZeroes(crc32c_t initial_crc, size_t length);
+
+// MemcpyCrc32c()
+//
+// Copies `src` to `dest` using `memcpy()` semantics, returning the CRC32C
+// value of the copied buffer.
+//
+// Using `MemcpyCrc32c()` is potentially faster than performing the `memcpy()`
+// and `ComputeCrc32c()` operations separately.
+crc32c_t MemcpyCrc32c(void* dest, const void* src, size_t count,
+                      crc32c_t initial_crc = ToCrc32c(0));
+
+// -----------------------------------------------------------------------------
+// CRC32C Arithmetic Functions
+// -----------------------------------------------------------------------------
+
+// The following functions perform arithmetic on CRC32C values, which are
+// generally more efficient than recalculating any given result's CRC32C value.
+
+// ConcatCrc32c()
+//
+// Calculates the CRC32C value of two buffers with known CRC32C values
+// concatenated together.
+//
+// Given a buffer with CRC32C value `crc1` and a buffer with
+// CRC32C value `crc2` and length, `crc2_length`, returns the CRC32C value of
+// the concatenation of these two buffers.
+//
+// This operation has a runtime cost of O(log(`crc2_length`)).
+crc32c_t ConcatCrc32c(crc32c_t crc1, crc32c_t crc2, size_t crc2_length);
+
+// RemoveCrc32cPrefix()
+//
+// Calculates the CRC32C value of an existing buffer with a series of bytes
+// (the prefix) removed from the beginning of that buffer.
+//
+// Given the CRC32C value of an existing buffer, `full_string_crc`; The CRC32C
+// value of a prefix of that buffer, `prefix_crc`; and the length of the buffer
+// with the prefix removed, `remaining_string_length` , return the CRC32C
+// value of the buffer with the prefix removed.
+//
+// This operation has a runtime cost of O(log(`remaining_string_length`)).
+crc32c_t RemoveCrc32cPrefix(crc32c_t prefix_crc, crc32c_t full_string_crc,
+                            size_t remaining_string_length);
+// RemoveCrc32cSuffix()
+//
+// Calculates the CRC32C value of an existing buffer with a series of bytes
+// (the suffix) removed from the end of that buffer.
+//
+// Given a CRC32C value of an existing buffer `full_string_crc`, the CRC32C
+// value of the suffix to remove `suffix_crc`, and the length of that suffix
+// `suffix_len`, returns the CRC32C value of the buffer with suffix removed.
+//
+// This operation has a runtime cost of O(log(`suffix_len`))
+crc32c_t RemoveCrc32cSuffix(crc32c_t full_string_crc, crc32c_t suffix_crc,
+                            size_t suffix_length);
+
+// operator<<
+//
+// Streams the CRC32C value `crc` to the stream `os`.
+inline std::ostream& operator<<(std::ostream& os, crc32c_t crc) {
+  return os << static_cast<uint32_t>(crc);
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CRC_CRC32C_H_