Add new CRC-32C checksum functions to folly

[folly.git] / folly / detail / ChecksumDetail.h

diff --git a/folly/detail/ChecksumDetail.h b/folly/detail/ChecksumDetail.h
new file mode 100644 (file)
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+++ b/folly/detail/ChecksumDetail.h
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+/*
+ * Copyright 2013 Facebook, Inc.
+ *
+ * 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
+ *
+ *   http://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 FOLLY_DETAIL_CHECKSUMDETAIL_H_
+#define FOLLY_DETAIL_CHECKSUMDETAIL_H_
+
+namespace folly { namespace detail {
+
+/**
+ * Compute a CRC-32C checksum of a buffer using a hardware-accelerated
+ * implementation.
+ *
+ * @note This function is exposed to support special cases where the
+ *       calling code is absolutely certain it ought to invoke a hardware-
+ *       accelerated CRC-32C implementation - unit tests, for example.  For
+ *       all other scenarios, please call crc32c() and let it pick an
+ *       implementation based on the capabilities of the underlying CPU.
+ */
+uint32_t crc32c_hw(const uint8_t* data, size_t nbytes,
+    uint32_t startingChecksum = ~0U);
+
+/**
+ * Check whether a hardware-accelerated CRC-32C implementation is
+ * supported on the current CPU.
+ */
+bool crc32c_hw_supported();
+
+/**
+ * Compute a CRC-32C checksum of a buffer using a portable,
+ * software-only implementation.
+ *
+ * @note This function is exposed to support special cases where the
+ *       calling code is absolutely certain it wants to use the software
+ *       implementation instead of the hardware-accelerated code - unit
+ *       tests, for example.  For all other scenarios, please call crc32c()
+ *       and let it pick an implementation based on the capabilities of
+ *       the underlying CPU.
+ */
+uint32_t crc32c_sw(const uint8_t* data, size_t nbytes,
+    uint32_t startingChecksum = ~0U);
+
+
+}} // folly::detail
+
+#endif /* FOLLY_DETAIL_CHECKSUMDETAIL_H_ */